STEERABLE EXTENDABLE DEVICES
The present invention is a Distally Assembled Steerable Cannula (DASC), a robotically-manipulated device that can be deployed and extended within a patient's body by growing from its distal end, or can be used in non-medical applications. In some embodiments, growth occurs by sequentially assembling segments that interlock to form a rigid tube with a complex 3-D shape. The segments are individually transported through the growing cannula, and then assembled at the distal end. A segment can be wedge-shaped in profile, allowing adjustment of the local radius and plane of curvature of the cannula to be controlled by relative segment orientation.
This application is a continuation application of U.S. patent application Ser. No. 15/066,982 filed Mar. 10, 2016, which is a continuation-in-part of U.S. patent application Ser. No. 14/213,193, filed Mar. 14, 2104, now U.S. Pat. No. 9,282,993, issued Mar. 15, 2016, and claims priority to U.S. Provisional Application Ser. No. 61/791,692, filed Mar. 15, 2013 and Ser. No. 61/884,123, filed Sep. 29, 2013, the entire contents of each of which are incorporated herein by reference.
TECHNICAL FIELD OF THE INVENTIONThe present invention relates generally to the fields of medical devices, robotics, oil and gas, civil engineering, disaster robotics, as well as other fields.
STATEMENT OF FEDERALLY FUNDED RESEARCHNone.
BACKGROUND OF THE INVENTIONThis application relates in part to medical procedures, which comprise entering the patient's body with an instrument to remove, ablate, extract, aspirate, modify, or repair tissue and fluids; to perform diagnostic procedures; or to deliver therapeutic agents or devices. The application also relates to implanted devices and to non-medical devices.
Some medical procedures are minimally invasive; such procedures can improve outcomes, speed recovery, limit trauma, and allow earlier intervention. Cannulas and related, often hollow, tubular devices such as needles, catheters, tubes, and endoscopes, are commonly used in such procedures, allowing surgical tools (including powered tools such as microdebriders driven by rotating flexible shafts), diagnostic and therapeutic instruments, implants, and drugs to be introduced into the body and excised tissue and fluid to be removed. Yet due to obstructions such as bone or sensitive organs, current devices may be unable to access a target region, or only do so sub-optimally. A more invasive method, a riskier approach, or a worse outcome is thus sometimes unavoidable. Moreover, in a number of procedures for which multiple targeted regions within the body need to be accessed, it can be time-consuming and involve multiple punctures or incisions, even if access to a single region would be straightforward. These issues arise from the fact that many instruments are substantially rigid and straight and follow substantially straight paths within the body, whether within a hollow (i.e., gas- or liquid-filled) organ or lumen, or in solid tissue. Moreover, even instruments known to the art that are not rigid and/or not straight can also have difficulty in accessing certain regions of the body, as the following examples will illustrate.
There has been extensive research into steerable needles, cannulas, catheters, and endoscopes; snake-like robots; and other devices. To date such devices have been problematic and many remain experimental. Spinning steerable needles with asymmetric tips [1,2,3,4] offer small gauge sizes but have very large curvature/outer diameter (O.D.) ratios (e.g., 70:1 [5]), can only be deployed within solid tissue, and are difficult to control accurately due to varying tissue properties [6], etc. Concentric multi-tube superelastic nickel-titanium (Nitinol) needles [7,8,9,10,11] intended mostly for hollow regions offer relatively few shapes due to the small number of tubes; relatively large curvature/O.D. ratios [12]; limited stiffness; and small lumen/outside diameter ratios. Steerable catheters [13] and jointed, shape locking devices [14] have few degrees of freedom and sometimes large diameters. Snake-like robots [15,16,17] capable of following 3-D paths are typically 0.4-0.8″ diameter and use costly components; their lumen or inner diameter (I.D)/O.D. ratios also tend to be small. Finally, everting endoscopes [18] grow distally and are flexible but not steerable.
Given the limitations of instruments known to the art, there is a need for new, more capable and dexterous instruments capable of curved motion along desirable paths within the body, either within hollow (e.g., gas- or liquid-filled) regions or through solid tissue. Such instruments would preferably be deliverable with minimal difficulty and tissue trauma or damage and have a small outside diameter (e.g., 1-10 mm). They could provide a unique platform technology with the potential to impact a wide variety of medical specialties and procedures, including sinus and skull base surgery (where narrow passages and nearby critical structures make minimally invasive procedures difficult or impossible with current straight or angled instruments, e.g. in the frontal sinus, anterior cranial fossa, cavernous sinus, and brainstem), urology (where, for example, repeated access to specific regions of the kidney can be difficult), and interventional radiology (e.g., for biopsy and drainage while avoiding critical structures, and local regional therapy). Moreover, there is a need (e.g., for cochlear electrodes and annuloplasty rings) for implantable devices that can be delivered in a minimally invasive manner and which have complex 3-D curved shapes; this capability is currently very limited and could be greatly expanded by using the approaches of some embodiments of the invention.
SUMMARY OF THE INVENTIONAccording to some embodiments of the invention, a stable, controllable cannula is provided that follows an optimal 3-D path—through gas or liquid-filled volumes or solid tissue—to reach virtually any target at any approach angle, and do so without iterative, time-consuming, and potentially traumatic manipulation by the clinician.
Such a device, which we term a “distally-assembled steerable cannula” (hereinafter, “DASC”), is fundamentally different from existing steerable needles, cannulas, catheters, and snake robots that rely on distally sliding and articulating. DASC is unique in several aspects. For example, it may be deployed within a patient's body entirely through distal growth, extending at its distal tip to follow a controlled 3-D path, while shape is maintained everywhere along the device. Moreover, it may be assembled in vivo from multiple, discrete pieces (interlocking segments or rings), be continuously assembled from a strip, or grow as an everting, steerable tube, offering an unprecedented number of possible 3-D shapes. These shapes may include multiple bends in multiple planes at various locations along the length of the cannula. Moreover, the cannula can vary its overall length up to a maximum. These attributes together can greatly facilitate operation within confined spaces. DASC provides an enormous number of degrees of freedom, yet does not require many actuators, since the mechanisms providing those degrees of freedom are self-locking and are accessed sequentially. DASC offers the ability to make tight turns (e.g., a 2:1 radius of curvature to O.D. ratio); for example, a 0.120″ O.D. device could make a full 180° turn in a space only ˜0.7″ wide. DASC also provides an unusually large lumen/working channel (e.g., a 0.9:1.0 lumen/O.D. ratio)—comparable to a non-steerable catheter—enabling more instruments to be used simultaneously; improving endoscopic visualization, irrigation, and aspiration; and allowing more tissue to be excised (e.g., for biopsy or tumor resection).
DASC can serve as a stable, passive conduit that provides access and support to other devices (e.g., articulated endoscopes, forceps, bipolar diathermy and monopolar cautery devices, laser fibers, graspers, dissectors, scissors, knives, needles, needle drivers, spatulas, or other instruments, at least one of which can be used at a time, and which can be rapidly exchanged), for example, in endoscopic surgery, laparoscopic, single port, and natural orifice translumenal endoscopic surgery, or to infuse or aspirate liquids. However, unlike prior-art passive devices, DASC can be easily re-shaped distally without having to first withdraw it and re-insert it during a procedure. Thus, DASC can be disassembled partially and then reassembled such that the distal end moves to a new position and/or changes its approach angle to the target region, providing, for example, a stable platform for procedures which cover multiple sites or wide areas.
DASC can be image-guided (e.g., via pre- or peri-operative CT, fluoro (portions of DASC may be made radiopaque), MM, ultrasound, and/or direct visualization), can be “driven” precisely in real time by a clinician (e.g., using a joystick), or can automatically grow according to an optimal, pre-determined trajectory, with optional real-time correction. It could be optimized for rigidity (e.g., for tissue manipulation) or instead, for compliance, e.g., to approximate the modulus of tissue. The tip of a DASC device can be made to sense force, helping a clinical detect obstructions and choose an optimal trajectory for deployment.
In some embodiments, DASC grows from its distal end by sequentially assembling flexible segments or rings that interlock to form a rigid, self-supporting tube with a complex, programmable 3-D shape. The segments or rings are temporarily deformed and individually transported through the growing cannula by a flexible shaft or “smart stylet” (hereinafter the “stylet”), then assembled by the stylet at the distal end. Each ring is wedge-shaped in profile; by robotically mating the ring at a preset orientation with respect to the next-most-proximal ring, the local radius of curvature and direction of the cannula can be precisely controlled. A fully-deployed cannula may comprise over 100 rapidly-assembled segments or rings. Since each ring can be mated in a number (e.g., eight or more) orientations, the range of possible 3-D configurations—and thus cannula's reachable workspace and set of approach angles—is vast. DASC can be scaled down to an O.D. (outside diameter) as small as 0.04″ (1 mm, 3 French) with a lumen >90% of the O.D., or can be scaled larger if required. As an example of a DASC suitable for sinus surgery, dimensions might be 0.12-0.16″ O.D., 0.09-0.13″ I.D. (inside diameter), 4-5″ overall length, and 0.3-0.4″ radius of curvature.
In one embodiment, the present invention includes an elongatable, steerable apparatus capable of growing from a proximal end to a distal end through a process of assembly wherein one or more segments are added to the distal end of the apparatus, the apparatus comprising: a first segment having a lumen therethrough, the first segment having a proximal end and a distal end; and a second segment having a lumen, a proximal end, and a distal end, wherein the second segment is deliverable via a segment transporter to the distal end of the first segment, wherein the segment transporter attaches the second segment to the first segment, wherein the second segment is capable of changing the growth direction (i.e., the local radius and plane of curvature) of the distal end of the apparatus and of one or more subsequent segments. In one aspect, additional segments are transferred to the distal end through the lumen formed of at least one of the first, the second and one or more subsequent segments. In another aspect, the growth is the result of everting a tube formed by two or more segments. In another aspect, the growth is the result of transferring additional segments to the distal end. In another aspect, at least the first, second or subsequent segments are at least one of triangular, circular, elliptical, polygonal, rectangular, square, or combination thereof. In another aspect, the at least first, second or subsequent segments comprise at least one of plastic, metal, rubber, latex, polymer, composite, elastomer, thermoplastic elastomer, synthetic rubber, natural rubber, melt processable rubber, propylene oxide elastomer, ethylene-isoprene elastomer, elastic polyvinyl chloride, silicone elastomer, elastic polyurethane, ethylene-vinyl acetate elastomer, or non-polymeric elastomer. In another aspect, at least the first, second or subsequent segments are metal and comprise at least one of titanium, vanadium, aluminum, nickel, tantalum, zirconium, chromium, silver, gold, silicon, magnesium, niobium, scandium, platinum, cobalt, palladium, manganese, molybdenum and alloys thereof, zirconium-titanium-tantalum alloys, superelastic nickel-titanium, and stainless steel. In another aspect, the segment transporter is defined further as a stylet that is comprised of at least one of a superelastic nickel-titanium, stainless steel, plastic, thermoplastic, elastomer, polyethylene terephthalate, polyethylene terephtalate glycol-modified, rubber, vinyl, latex, or silicone. In another aspect, at least one segment may be radiopaque. In another aspect, at least the first, second, or subsequent segments, may attach or interlock to each other by friction, abrasive contact surfaces, self-adhesive strips, hook and loop fasteners, hooks and eyes, ties, tabs, holes, buckles, belts, pins, elastic bands, rubber bands, snaps, clasps, magnets, zippers, DUAL LOCK™, or VELCRO™ tape fasteners. In another aspect, at least the first, second, or subsequent segments, are wedge-shaped and the addition of subsequent segments causes the extension of the apparatus at the distal end with a segment that is not wedge-shaped, a segment that is wedge-shaped on the distal or the proximal face, or a segment that is wedge-shaped on both the distal and proximal faces. In another aspect, at least the first, second, or subsequent segments, are wedge-shaped having a wedge angle that varies from 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 22.5, 25, 33, 33.3, 35, 40, 42.5, 45, 50, 60, 66.6, 70, 75, 80, or 85 degrees at the proximal or distal face, or on both faces. In another aspect, at least the first, second, or subsequent segments, are wedge-shaped and the segments interlock in increments of 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 22.5, 25, 33, 33.3, 35, 40, 42.5, 45, 50, 60, 66.6, 70, 75, 80, 85, 90, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, 200, 205, 210, 215, 220, 225, 230, 235, 240, 245, 250, 255, 260, 265, 270, 275, 280, 285, 290, 295, 300, 305, 310, 315, 320, 325, 330, 335, 340, 345, 350, 355, or 360 degrees about the longitudinal axis of the apparatus. In another aspect, at least the first, second, or subsequent segments, are wedge-shaped but also tapered along the longitudinal axis of the apparatus to expand or decrease an inner diameter of the apparatus. In another aspect, the central cannula is defined further as a having a proximal and distal end, wherein the segment transporter travels back and forth within the cannula to at least one of compress, swivel, transport, rotate, or add the subsequent segments to the distal end of the apparatus. In another aspect, the cannula is pre-loaded with some or all the segments necessary to reach a pre-determined length and shape.
In another embodiment, the present invention includes a method of lengthening and steering an apparatus capable of growing from a proximal end to a distal end through a process of assembly wherein one or more segments are added to the distal end of the apparatus, the apparatus comprising: obtaining a first segment having a lumen therethrough, the first segment having a proximal end and a distal end; and adding a second segment having a lumen, a proximal end, and a distal end, wherein the second segment is deliverable via a segment transporter to the distal end of the first segment, wherein the segment transporter attaches the second segment to the first segment, wherein the second segment is capable of changing the growth direction of the distal end of the apparatus and of one or more subsequent segments. In one aspect, additional segments are transferred to the distal end through the lumen formed of at least one of the first, the second and one or more subsequent segments. In another aspect, the growth is the result of everting a tube formed by the two or more segments. In another aspect, the growth is the result of transferring additional segments to the distal end. In another aspect, at least the first, second or subsequent segments are at least one of triangular, circular, elliptical, polygonal, rectangular, square, or combination thereof. In another aspect, the at least first, second or subsequent segments comprise at least one of plastic, metal, rubber, latex, polymer, composite, elastomer, thermoplastic elastomer, synthetic rubber, natural rubber, melt processable rubber, propylene oxide elastomer, ethylene-isoprene elastomer, elastic polyvinyl chloride, silicone elastomer, elastic polyurethane, ethylene-vinyl acetate elastomer, or non-polymeric elastomer. In another aspect, at least the first, second or subsequent segments are metal and comprise at least one of titanium, vanadium, aluminum, nickel, tantalum, zirconium, chromium, silver, gold, silicon, magnesium, niobium, scandium, platinum, cobalt, palladium, manganese, molybdenum and alloys thereof, zirconium-titanium-tantalum alloys, superelastic nickel-titanium, or stainless steel. In another aspect, the segment transporter is defined further as a stylet that is at least one of a superelastic nickel-titanium, stainless steel, plastic, thermoplastic, elastomer, polyethylene terephthalate, polyethylene terephtalate glycol-modified, rubber, vinyl, latex, or silicone. In another aspect, at least the first, second, subsequent segments, or the cannula is radiopaque. In another aspect, at least the first, second, or subsequent segments, may attach or interlock to each other by friction, abrasive contact surfaces, self-adhesive strips, hook and loop fasteners, hooks and eyes, ties, tabs, holes, buckles, belts, pins, elastic bands, rubber bands, snaps, clasps, magnets, zippers, DUAL LOCK™, or VELCRO™ tape fasteners. In another aspect, at least the first, second, or subsequent segments, are wedge-shaped and the addition of subsequent segments causes the extension of the apparatus at the distal end with a segment that is not wedge-shaped, a segment that is wedge-shaped on the distal or the proximal face, or a segment that is wedge-shaped on both the distal and proximal faces. In another aspect, at least the first, second, or subsequent segments, are wedge-shaped having a wedge angle that varies from 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 22.5, 25, 33, 33.3, 35, 40, 42.5, 45, 50, 60, 66.6, 70, 75, 80, or 85 degrees at one or both ends. In another aspect, at least the first, second, or subsequent segments, are wedge-shaped and the segments interlock in increments of 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 22.5, 25, 33, 33.3, 35, 40, 42.5, 45, 50, 60, 66.6, 70, 75, 80, 85, 90, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, 200, 205, 210, 215, 220, 225, 230, 235, 240, 245, 250, 255, 260, 265, 270, 275, 280, 285, 290, 295, 300, 305, 310, 315, 320, 325, 330, 335, 340, 345, 350, 355, or 360 degrees about the longitudinal axis of the apparatus. In another aspect, at least the first, second, or subsequent segments, are wedge-shaped but also tapered along the longitudinal axis the apparatus to expand or decrease an inner diameter of the apparatus. In another aspect, the central cannula is defined further as a having a proximal and distal end, wherein the segment transporter travels back and forth within the cannula to at least one of compress, swivel, transport, rotate, or add the subsequent segments to the distal end of the apparatus. In another aspect, the cannula is pre-loaded with some or all the segments necessary to reach a pre-determined length and shape.
In another embodiment, the present invention includes a cannula capable of growing from a proximal end to a distal end and capable of a non-linear configuration comprising: one or more segments having a lumen and substantially cylindrical in their uncompressed state and having a distal face and a proximal face that are non-parallel, wherein the one or more segments can be transformed into a non-cylindrical, substantially elliptical shape; a segment transporter that transports one or more additional segments in their non-cylindrical, substantially elliptical shape through the substantially cylindrical segments; and a coupling mechanism that engages the one or more segments to an adjacent segment, whereby at least one of the segments is transported through the lumen of the one or more substantially cylindrical segments to reach a distal location, and transformed to couple to the most distal of the segments, thereby growing the cannula. In one aspect, the segment transporter is capable of at least one of swiveling, rotating, coupling or transporting a segment. In another aspect, a swiveling axis of the segment is substantially parallel to a minor axis of the non-cylindrical, substantially elliptical shape of the segment. In another aspect, a distal face of a first segment is substantially perpendicular to a substantially cylindrical axis of the first segment, and a proximal face of a first segment is substantially non-perpendicular to the substantially cylindrical axis of the first segment; a distal face of a second segment is substantially non-perpendicular to a substantially cylindrical axis of the second segment, and a proximal face of a second segment is substantially perpendicular to the substantially cylindrical axis of the second segment; and wherein the swiveling axis is substantially perpendicular to a plane formed by the substantially cylindrical axis and a normal to the substantially non-perpendicular face of the segment. In another aspect, the segments comprise one or more holes along a distal edge or face of the segment and one or more tabs that extend from a proximal edge or face of the segments, wherein the one or more tabs fit within the one or more holes to couple two adjacent segments. In another aspect, each segment comprises two or more tabs that are equally spaced around the circumference of the segment. In another aspect, the tabs are substantially aligned with the major and minor axes of the substantially elliptical shape assumed by the rings when transformed. In another aspect, each segment comprises two holes that are substantially parallel to the swiveling axis. In another aspect, at least one first tab in the distal segment of a pair of adjacent segments enters a hole in the proximal segment of a pair of adjacent segments from the inside of the proximal segment, and at least one second tab on the non-opposite side of the distal segment enters a hole from the outside of the proximal segment to couple the segments. In another aspect, each of the first and second segments alternate.
In another embodiment, the present invention includes an elongatable, steerable cannula capable of growing from a proximal end to a distal end through a process of assembly wherein one or more segments are added to the distal end of the cannula, the cannula comprising: a first flexible segment substantially cylindrical in axial cross section when uncompressed and substantially elliptical when compressed, having a first lumen therethrough, the first segment having a first proximal face substantially perpendicular to a first substantially cylindrical axis and provided with one or more first male coupling elements, and a first distal face substantially non-perpendicular to the substantially cylindrical axis and provided with a first plurality of female coupling elements; a second flexible segment substantially cylindrical in axial cross section when uncompressed and substantially elliptical when compressed, having a second lumen therethrough, the second segment having a second proximal face substantially non-perpendicular to a second substantially cylindrical axis and provided with one or more second male coupling elements, and a second distal face substantially perpendicular to the second substantially cylindrical axis and provided with a second plurality of female coupling elements; a flexible shaft provided with grippers able to grip said first and said second segment to compress and allow to decompress said segments, swivel or allow to swivel said segments about axes substantially parallel to the minor axes of said first and second segments when compressed and substantially elliptical, and transport said segments through said lumen; wherein said flexible shaft transports said second segment through said lumen of said first segment, then rotates said second segment as required around an axis substantially coincident with the longitudinal axis of the flexible shaft, brings the proximal face of said second segment in contact with the distal face of said first segment, allows said second segment to decompress while allowing two of said second male coupling elements to enter two of said first plurality of female coupling elements from the inside and two of said second male coupling elements to enter two of said first plurality of female coupling elements from the outside; and wherein said flexible shaft transports said first segment through said lumen of said second segment, rotates said first segment as required around an axis substantially coincident with the longitudinal axis of the flexible shaft, brings the proximal face of said first segment in contact with the distal face of said second segment, then allows said first segment to decompress while allowing two of said first male coupling elements to enter two of said second plurality of female coupling elements from the inside and two of said first male coupling elements to enter two of said second plurality of female coupling elements from the outside. In another aspect, the segments comprise a superelastic nickel-titanium material. In another aspect, the first and second male coupling elements comprise interlocking male and female elements such that the adjacent segments are mechanically interlocked when the segments are decompressed. In another aspect, a plurality of first and second segments is arranged in an alternating pattern within the cannula. In another aspect, the angle between the first proximal face and second distal face is varied by varying the relative orientation of the first and second segments when coupled together. In another aspect, the relative orientation is varied as required by rotating the second segment substantially about an axis substantially coincident with the longitudinal axis of the flexible shaft prior to coupling the second segment to the first segment. In another aspect, the flexible shaft comprises a superelastic nickel-titanium material. In another aspect, the minor axis of the compressed, substantially elliptical second segment is substantially perpendicular to the plane defined by the substantially non-perpendicular second proximal face and the second substantially cylindrical axis, and wherein the minor axis of the compressed, substantially elliptical first segment is substantially perpendicular to the plane defined by the substantially non-perpendicular first distal face and the first substantially cylindrical axis. In another aspect, the second segment is swiveled about its minor axis and its major axis is substantially parallel to the first cylinder axis during transport by the flexible shaft, and wherein the first segment is swiveled about its minor axis and its major axis is substantially parallel to the second cylinder axis during transport by the flexible shaft. In another aspect, the second segment is rotated as required relative to the first segment prior to allowing the second segment to decompress, and wherein the first segment is rotated relative to the second segment prior to allowing the first segment to decompress. In another aspect, the grippers are supported by a fork that is compressed by a sliding tube. In another aspect, the grippers are supported by a flexible ring that is expanded by applying tension to a wire attached to its distal end.
In another embodiment, the present invention includes an elongatable, steerable cannula capable of growing from a proximal end to a distal end through a process of assembly wherein one or more segments are added to the distal end of the cannula, the cannula comprising: a first expandable segment substantially cylindrical in axial cross section having a first lumen therethrough, the first segment having a first proximal face substantially perpendicular to a first substantially cylindrical axis and provided with a first plurality of male coupling elements, and a first distal face substantially non-perpendicular to the substantially cylindrical axis and provided with a first plurality of female coupling elements; a second expandable segment substantially cylindrical in axial cross section having a second lumen therethrough, the second segment having a second proximal face substantially non-perpendicular to a second substantially cylindrical axis and provided with a second plurality of male coupling elements, and a second distal face substantially perpendicular to the second substantially cylindrical axis and provided with a second plurality of female coupling elements; a flexible shaft provided with an expanding member to expand and orient said first and said second segments, and transport said segments through said lumens; wherein said flexible shaft transports said second segment through said lumen of said first segment, then expands said second segment and allows second plurality of male coupling elements to enter said first plurality of female coupling elements from the inside; and wherein said flexible shaft transports said first segment through said lumen of said second segment, then expands said first segment and allows first plurality of male coupling elements to enter said second plurality of female coupling elements from the inside.
In one embodiment, the present invention also includes an elongatable, steerable cannula capable of growing from a proximal end to a distal end through a process of everting, the cannula comprising: an expandable tube having a relatively flexible inner wall of relatively small diameter and an relatively inflexible outer wall of relatively large diameter; a device for everting the tube to grow the cannula from its distal end by progressively transforming the inner wall into an outer wall; a steering mechanism for controlling the direction in which the cannula grows by varying the rate at which the inner wall is transformed into outer wall according to location around the circumference of the inner wall. In one aspect, the tube comprises braided superelastic nickel-titanium wire. In another aspect, the tube comprises an elastomer.
In another embodiment, the present invention includes a method of making an elongatable, steerable cannula capable of growing from a proximal end to a distal end through a process of assembly wherein one or more segments are added to the distal end of the cannula, the method comprising: obtaining a first flexible segment substantially cylindrical in axial cross section when uncompressed and substantially elliptical when compressed, having a first lumen therethrough, the first segment having a first proximal face substantially perpendicular to a first substantially cylindrical axis and provided with one or more first male coupling elements, and a first distal face substantially non-perpendicular to the substantially cylindrical axis and provided with a first plurality of female coupling elements; positioning a second flexible segment substantially cylindrical in axial cross section when uncompressed and substantially elliptical when compressed, having a second lumen therethrough, the second segment having a second proximal face substantially non-perpendicular to a second substantially cylindrical axis and provided with one or more second male coupling elements, and a second distal face substantially perpendicular to the second substantially cylindrical axis and provided with a second plurality of female coupling elements; inserting a flexible shaft provided with grippers able to grip said first and said second segment to compress and allow to decompress said segments, swivel or allow to swivel said segments about axes substantially parallel to the minor axes of said first and second segments, and transport said segments through said lumen; wherein said flexible shaft transports said second segment through said lumen of said first segment, rotates said second segment as required around an axis substantially coincident with the longitudinal axis of the flexible shaft, brings the proximal face of said second segment in contact with the distal face of said first segment, then allows said second segment to decompress while allowing two of said second male coupling elements to enter two of said first plurality of female coupling elements from the inside and two of said second male coupling elements to enter two of said first plurality of female coupling elements from the outside; and wherein said flexible shaft transports said first segment through said lumen of said second segment, rotates said first segment as required around an axis substantially coincident with the longitudinal axis of the flexible shaft, brings the proximal face of said first segment in contact with the distal face of said second segment, then allows said first segment to decompress while allowing two of said first male coupling elements to enter two of said second plurality of female coupling elements from the inside and two of said first male coupling elements to enter two of said second plurality of female coupling elements from the outside.
In another embodiment, the present invention includes a method of making an elongatable, steerable cannula capable of growing from a proximal end to a distal end through a process of assembly wherein one or more segments are added to the distal end of the cannula, the cannula comprising: obtaining a first expandable segment substantially cylindrical in axial cross section having a first lumen therethrough, the first segment having a first proximal face substantially perpendicular to a first substantially cylindrical axis and provided with a first plurality of male coupling elements, and a first distal face substantially non-perpendicular to the substantially cylindrical axis and provided with a first plurality of female coupling elements; positioning a second expandable segment substantially cylindrical in axial cross section having a second lumen therethrough, the second segment having a second proximal face substantially non-perpendicular to a second substantially cylindrical axis and provided with a second plurality of male coupling elements, and a second distal face substantially perpendicular to the second substantially cylindrical axis and provided with a second plurality of female coupling elements; and inserting a flexible shaft provided with an expanding member to expand and orient said first and said second segments, and transport said segments through said lumens; wherein said flexible shaft transports said second segment through said lumen of said first segment, rotates said second segment as required around an axis substantially coincident with the longitudinal axis of the flexible shaft, brings the proximal face of said second segment in contact with the distal face of said first segment, then expands said second segment and allows said second plurality of male coupling elements to enter said first plurality of female coupling elements from the inside; and wherein said flexible shaft transports said first segment through said lumen of said second segment, rotates said first segment as required around an axis substantially coincident with the longitudinal axis of the flexible shaft, brings the proximal face of said first segment in contact with the distal face of said second segment, then expands said first segment and allows said first plurality of male coupling elements to enter said second plurality of female coupling elements from the inside.
In another embodiment, the present invention includes a method of making an elongatable, steerable cannula capable of growing from a proximal end to a distal end through a process of everting, the cannula comprising: obtaining a flexible, expandable tube capable of being everted, positioning a device for everting the tube to grow the cannula from its distal end by progressively transforming the inner wall into an outer wall, rigidifying the outer wall as it is formed; and inserting a steering mechanism for controlling the direction in which the rigid outer wall grows by varying the rate, according to location around the circumference of the inner wall, at which the inner wall is transformed into the outer wall
For a more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures and in which:
While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention and do not delimit the scope of the invention.
To facilitate the understanding of this invention, a number of terms are defined below. Terms defined herein have meanings as commonly understood by a person of ordinary skill in the areas relevant to the present invention. Terms such as “a”, “an” and “the” are not intended to refer to only a singular entity, but include the general class of which a specific example may be used for illustration. The terminology herein is used to describe specific embodiments of the invention, but their usage does not delimit the invention, except as outlined in the claims.
As used herein, the units that may be used to add or reduce the length of an apparatus of the present invention may be referred to individually as a segment or ring, when there are two or more they can be referred to as segments or rings. The segment(s) or ring(s) the may be of any shape or shapes, including, e.g., triangular, circular, elliptical, polygonal, rectangular, square, or combinations thereof, including composite shapes, and extensions from the edge(s) of the segments or openings cut into the segments. Note also that the terms segment and ring may be used interchangeably herein.
The segment(s) can be made from, e.g., plastic, metal, rubber, latex, polymer, composite, elastomeric, a thermoplastic elastomer, a synthetic rubber, a natural rubber, a melt-processable rubber, a propylene oxide elastomer, an ethylene-isoprene elastomer, an elastic polyvinyl chloride, a silicone elastomer, an elastic polyurethane, an ethylene-vinyl acetate elastomer, or a non-polymeric elastomer, or combinations thereof. The segments or rings can be made from a wide variety of materials or composites, which can include polymer(s) selected from at least one of polyglycolic acid (PGA), polylactic acid (PLA), poly (dioxanone) (PDO), poly (l-lactide) (LPLA), poly (dl-lactide) (DLPLA), poly (glycolide-co-trimethylene carbonate) (PGA-TMC), poly (l-lactide-co-glycolide) (PGA-LPLA), poly (dl-lactide-co-glycolide) (PGA-DLPLA), poly (l-lactide-co-dl-lactide) (LPLA-DLPLA), poly(glycolide-co-trimethylene carbonate-co-dioxanone) (PDO-PGA-TMC), poly(ε-caprolactone), poly(dioxanone)(a polyether-ester), poly (lactide-co-glycotide), poly(SA-HDA anhydride), poly(orthoester), or polyglyconate. The segments or rings may be at least partially made from a metal, such as, e.g., titanium, vanadium, aluminum, nickel, tantalum, zirconium, chromium, silver, gold, silicon, magnesium, niobium, scandium, platinum, cobalt, palladium, manganese, molybdenum and alloys thereof, zirconium-titanium-tantalum alloys, nitinol (nickel-titanium, e.g., superelastic), and stainless steel.
As regards the central cannula or segment delivery and removal device, it can include an expandable portion that can be, e.g., plastic, thermoplastic, elastomer, polyethylene terephthalate, polyethylene terephtalate glycol-modified, rubber, vinyl, latex, and silicone. Non-limiting examples of a stylet or assembly head is shown herein that include one or more clasps that permit the addition or removal of a segment or ring while also providing orientation for the segment or ring, e.g., to change the direction of the opening within the elongatable apparatus and thus the outside of the apparatus as well.
The segments can be attached to each other via a wide variety of fasteners or adhesives, which can be integrated into the segments themselves. Non-limiting examples of these fasteners or adhesives include tabs and openings in the top, bottom or side walls of the segment(s) that attach or interlock to each other by friction, mechanical interlocking, abrasive contact surfaces, self-adhesive strips, hook and loop fasteners, hooks and eyes, ties, tabs, buckles, belts, pins, elastic bands, rubber bands, snaps, clasps, magnets, zippers, DUAL LOCK™ (3M Company, St. Paul, Minn.), and VELCRO® tape fasteners.
As regards the change in direction by the addition of segments, the segments can be wedge-shaped such that when viewed perpendicular to the segment axis the segment comprising a “wedge angle”, such that addition of a subsequent segment can cause the extension to be straight (i.e., continue in the same direction as the next most proximal segment), or cause a rotation (i.e., a change in direction) of the addition as a result of the wedge angle. In certain non-limiting examples, the wedge angle can vary from, e.g., 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 22.5, 25, 33, 33.3, 35, 40, 42.5, 45, 50, 60, 66.6, 70, 75, 80, or 85 degrees between segment(s) at one or both ends.
Known to the art are three basic methods by which an instrument 10 can be curved with the goal of its distal end reaching region 2. Referring to
In some cases, the instrument can be curved into shapes other than the path shape such that with sufficient and skilled manipulation, the distal end 19 can ultimately reach region 2. However, such manipulation may be by trial-and-error, increasing procedural time and in some cases, patient exposure to X-rays or other radiation. Removal of the instrument would normally involve a similar process. Moreover, if the instrument is surrounded by tissue, it cannot as a whole penetrate and glide smoothly through the tissue by leading with distal end 19. Rather, a great deal of lateral movement of the instrument must occur, requiring the relatively broad side of the instrument to penetrate or deform surrounding tissue. This can be both difficult to accomplish (e.g., requiring significant force) and traumatic/damaging to the tissue.
A third method that might be considered for reaching region 2 is the method used, for example, in interventional cardiology. In this method, a guidewire—which can be provided with pre-curved or actively-steerable distal tips—would first be guided and delivered to region 2 and then a flexible instrument such as a catheter would be slid distally over the guidewire. However, since this method requires delivery of guidewire before the instrument is delivered, it is appropriate when the guidewire can itself follow a pre-existing path (e.g., such as within a lumen like an artery) or can be adequately controlled and steered (e.g., magnetically). The method is generally unsuitable for efficiently and accurately accessing region 2 when it is located, as in the figure, within a gas- or liquid-filled cavity or within solid tissue.
1st EmbodimentIn a 1st embodiment of the invention, an instrument enters the body and is delivered along a desired path such as path 16 of
In
As shown in
For use in a gas or liquid environment, the instrument needs to be relatively rigid, so each section preferably forms a rigid, well-interlocked joint with its neighboring section. Rigid interlocking may be achieved by friction; protrusions on one section interacting with features such as protrusions, cavities, or perforations on another; by textures, or by other suitable means. In the case of a permanent cannula, sections may be attached by adhesive, welding, brazing, soldering, riveting, and other methods known to the art.
The expansion of section 36 can be accomplished by a variety of means. In some embodiment variations, it is the result of the section springing back to its natural diameter after having been compressed. In other embodiment variations it is the result of a deformation that plastically deforms the material of section 36 outwards (e.g., section 36 may be designed similar to a metal stent known to the art), after allowing for elastic springback/recoil. For example, an expanding balloon or bladder may be used to deform the section to an approximately circular shape.
In still other embodiment variations, it is the result of section 36 being elastically deformed outwards and held in its expanded position (e.g., by a ratcheting mechanism or clips; or if, for example, designed as a braided superelastic nickel-titanium tube, by maintaining axial tension). In
In embodiment variations in which sections are naturally of larger diameter and spring back after having been compressed, means of keeping the sections compressed until they are delivered to the distal end of the cannula may be used. For example, a balloon may be provided with hooks on its surface that engage features on the inside surfaces of section such as section 36. Once so engaged, by collapsing the balloon or allowing it to collapse, section 36 is forced to become compressed so it can fit through other sections. In some embodiment variations, sections such as section 36 may comprise an elastic tube, for example, a braided wire tube designed to reduce in diameter when elongated axially, and increase in diameter when compressed axially, or an elastomeric tube. In the case of sections, which are normally expanded (i.e., having a larger diameter when no forces act on them), they may be delivered through other sections by temporarily stretching them axially, and interlocking them to other sections by releasing the axial tension.
In some embodiment variations, the cannula can be disassembled and retracted (e.g., after completion of a clinical procedure) by approximately reversing the steps shown in
In some embodiment variations, sections transported distally are enlarged further than shown in
The steps shown in
The steps shown in
In
Before section 96 has expanded completely and interlocked with section 94, it is tilted in the desired direction by pulling on at least one of the wires 106. Tension on wires 106 may be removed when not needed, as is the case with one of wires 106 after full expansion of balloon 100 in
In this variation and in some other variations, the edges of sections are more rounded, chamfered, or tapered than shown in
Once the distal assembly process has been completed to access the target region and the clinical procedure has been completed, disassembly of the instrument can be achieved by approximately reversing the assembly sequence, using the balloon and its associated components to remove and retract each section, beginning with the most distal section.
The steps shown in
In
As before, disassembly of the instrument can be achieved by approximately reversing the assembly sequence beginning with the most distal section. The steps shown in
In the configuration shown in
In some embodiment variations, friction between band 146 and surfaces 138 of section 142 can join sections 142 and 144 together with sufficient stiffness. In other embodiment variations, other means of interlocking are used. In some embodiment variations, after all sections are distally assembled into an instrument, the OD of the most proximal section (which has been maintained by a suitable mechanism) is reduced, causing the ODs of all the more distal segments to also be reduced. As the OD of a section is reduced, the proximal ends of a given segment come into contact with the distal ends of the section just proximal to it. Such contact, as the segments clamp one another, leads to additional friction and in some embodiment variations other interlocking features may be provided. For example, protrusions on the sides of the proximal ends of segments in section 144 may fit into holes on the facing surfaces: the distal end of segments from a section 142. Interlocking mechanisms such as this preferably are designed to allow for positive interlocking regardless of the relative orientation of neighboring sections.
6th EmbodimentTo form a rigid cannula, rings should not move relative to their neighbors. Among the methods available to prevent such movement are interlocking protrusions on, for example, the bottom of odd-numbered rings, which fit into other protrusions, cavities, or perforations on, for example, the top of even-numbered rings. For example, radially-arranged gear-like teeth on both the upper and lower surfaces of rings can engage one another in one of many discrete orientations.
Also not shown in
In some embodiment variations, the rings of
In some embodiment variations, rings may interlock using interlocking textured surfaces such as VELCRO® or an array of small mushroom-like protrusions (e.g., the DUAL LOCK™ fastener from the 3M Company, St. Paul, Minn.). The gear teeth already discussed provide a finite, quantized number of relative angles between rings, but in some embodiment variations, even fewer (e.g., 3-6) relative angles may be required. In such cases, providing rings with just a few protrusions on one surface and corresponding depressions on the opposite surface may suffice.
In some embodiment variations, rings may be held tightly against one another by one or more tensioned wires which run through the rings from most proximal to most distal; as a new ring is added, the wire(s) are transferred to the most distal ring. In some embodiment variations, rings are held against one another by magnetism. For example, the rings may be made of a ferromagnetic material, and placed in a magnetic field, or a magnet may be in contact with the most proximal ring and the magnetic flux conducted through the entire stack as more rings are added, making each new ring hold onto the previously-added ring. In some embodiment variations, magnetically-assisted contact may be used during the distal assembly process, but when all rings are deployed, another means of clamping the rings tightly against one another may be employed, such as one or more wires which run the length of the stack.
In some embodiment variations, the rings or at least one of their mating surfaces are compliant (e.g., an elastomer) such that when the rings are in contact, a seal is made between rings, thus allowing liquid or gas to be channeled without leakage from one end of the ring stack/cannula to the other.
In some embodiment variations, rings that are both offset as in
In
In some embodiment variations, rings may be pre-oriented or pre-selected such that when assembled, they form a cannula of the desired 3-D curvature, and little or no balloon rotation is required. In such variations, is may be important to prevent the rings from inadvertently rotating to an improper orientation before being assembled. One means of accomplishing this is to make the rings a shape other than round (e.g., polygonal) on their OD and make the inside of tube 183 have a matching shape that prevents ring rotation. In some embodiment variations, for example in the case of pre-oriented rings which require little or no rotation, the rings can have different wedge angles, rather than have all the same wedge angle.
In some embodiment variations, rings may not have substantially co-planar tops and bottoms. For example, segments such as segment 174 in
In some embodiment variations, in lieu of rings expanded radially as shown in
We now turn to a set of embodiments which may be more suitable for producing steerable instruments which are not necessarily rigid on their own (if unsupported by surrounding tissue or other material) and may therefore be better suited for applications in which it is desirable to access a target region embedded in surrounding tissue.
To extend straight ahead, penetrating through tissue, wires 204 are pulled an equal distance. In order to extend the instrument along a curved path, not all wires are pulled an equal distance or with an equal tension. For example, as shown in
The length of the everting tube can be adjusted prior to cannula delivery such that inner turns 200 are completely everted and the resulting lumen is larger—determined by the ID of the outer turns—than it would be if not completely everted.
Retraction of the cannula can be accomplished by pulling the tube formed by inner turns 200 proximally. Or, if the tube has completely everted in order to maximize the lumen, wires can be provided that are affixed to the proximal ends of the tube; pulling these can reverse the eversion of the tube.
8th EmbodimentWhen wires 244 are pulled in direction 248, barbs 246 engage loops 242 and pull inner walls 240 distally, further everting tube 236. After thus pulling inner walls 240 a short distance, wires 244 are then pulled in direction 250 a short distance such that barbs 246 pass in a proximal direction (i.e., proximally) through the next most proximal loops, engaging them in preparing for the next cycle, in which wires 244 are again pulled in direction 248. When all wires 244 are manipulated (e.g., alternating between pulling in directions 248 and 250) at the same rate, tube 236 everts and extends straight, forcing tip 252 into tissue. When wires 244 are not all manipulated at the same rate, tube 236 will tend to bend away from the direction in which the rate is higher, forcing tip 252 into tissue in a new direction. In some embodiment variations, tip 252 may also be tilted, e.g., through the use of wires such as wires 232 in
When wires 272 are pulled or cycled at a uniform rate, tube 266 everts uniformly and extends distally along a straight path. When wires 272 are pulled or cycled at a non-uniform rate, the distal extension is along a curved path whose direction and radius of curvature depend on the relative pulling/cycling rates.
12th EmbodimentWhen wires 292 are pulled in direction 296, anchors 294 grasp inner walls 290 and pull inner walls 290 distally, further everting tube 286. After pulling inner walls 290 a short distance, wires 292 are then pulled in direction 298 a shorter distance such that anchors 294 can grasp a more proximal region on inner walls 290 in preparation for the next cycle, in which wires 292 are again pulled in direction 296. When all wires 292 are manipulated (e.g., alternating between pulling in directions 296 and 298) at the same rate, tube 286 everts and extends straight, forcing the tip into tissue. When wires 244 (in
Everting versions of the cannula such as this one may in some embodiments incorporate a shape memory polymer that can transition from a rigid to a flexible state (e.g., when heated), or simply a thermoplastic which can soften when heated. Then, for example, heat can be applied to the inner walls (e.g., by radiant heater, hot air, laser, embedded resistive wires) as they evert to form the outer walls, making them flexible enough to both bend and stretch, which facilitates eversion. Once everted, the structure can rigidify. If the inner walls are also rigid, it can facilitate pushing them distally. However, if too flexible, they cannot conform to the outer walls of the cannula, which may in general be curved. Thus in some embodiment variations it is beneficial to keep the inner walls mostly flexible (e.g., by heating them with a hot air stream that is directed through the inner walls from proximal to distal end or vice-versa.
Everting versions of the cannula such as this one may in some embodiments incorporate a granular material between two walls of a double-walled tube; in some embodiment variations this is isolated within individual compartments which may be toroidal in shape and disposed axially along the tube. By apply vacuum to the regions of the tube which form outer walls and sealing the regions to hold vacuum, they can become rigid and hold their shape by virtue of jamming. Everting versions of the cannula such as this one may in some embodiments incorporate an electrorheological or magnetorheological fluid between two walls of a double-walled tube; in some embodiment variations this is isolated within individual compartments which may be toroidal in shape and disposed axially along the tube. By apply an electric or magnetic field to the regions of the tube which form outer walls, they can become rigid and hold their shape by virtue of greatly increased viscosity.
13th EmbodimentIf regions 302 are fed distally in direction 306, regions 304 will elongate in direction 306 as material from region 302 flows to the distal end of the tube 301, around the bend, and ends up on the outside as part of region 304. Strips 300 are joined by adhesive, seam welding, magnets, zippers, VELCRO®, DUAL LOCK™, etc. in such a way that if all strips 300 are fed distally at the same rate, the tube 301 resulting from joining them at their edges is straight. However, if strips 300 are fed at different rates, the tube 301 resulting from joining them at their edges will be curved. By adjusting the relative feed rates and/or the amount of stretch if strip 300 is stretchable, evolving/everting tube 301 can thus be made to curve along a 3-D path. In some cases, such as when the strip is made of an expanded metal-like perforated material, it may be compressed along its axis as well as being expanded. In some embodiment variations, more than 3 strips are used. For example, 6 strips may be fed distally, folded back onto themselves, and joined along their edges to form a tube with a hexagonal cross section. In such a case, the strips need not be curved initially, since there is adequate room to accommodate their width. Since unlike a triangular tube a hexagonal tube can collapse, appropriate bracing or reinforcement can be used, such as joining the strips using a method that provides rigid seams that maintain the strips at the correct relative angles.
14th EmbodimentFor windings in when the strip width or amount of overlap is constant, the cannula is straight. However, for windings in which width or overlap varies around the circumference, the winding becomes effectively tapered, producing a curvature in the cannula whose radius and plane depend on the location and magnitude of the variation.
15th EmbodimentIf all sacs at a given level (i.e., position along eversion/symmetry axis 317) are inflated to the same pressure, then assuming they are equivalent, tube/cannula 318 will grow in a direction parallel to axis 317. However, if the pressures are not equal, sacs with higher pressure and greater axial height will bend the growth direction away from themselves, causing the cannula to bend or curve as desired, along a 3-D path.
Retraction of the cannula can be accomplished by reversing rollers 332; sacs will enter chambers 324 and be emptied of their fluid contents and collapsed as they return to form inner walls 322 moving proximally.
In some embodiment variations, rather than providing sacs with a slit that can open to admit fluid, and chambers to fill sacs with fluid, sacs can be sealed and pierced by a needle (e.g., protruding from the surface of rollers 332). While so pierced, fluid can be injected into each sac. When the needle retracts, the sacs (e.g., if elastomeric) can re-seal, maintaining their charge of fluid within.
16th EmbodimentUnlocking or locking the rings requires one ring to be temporarily compressed into a substantially elliptical shape.
In the compressed state rings 370 can be transported through the cannula lumen toward distal end 372 (or towards the proximal end) by swiveling them so that the major axis 374 of the ellipse is substantially aligned with the direction of travel 376 (
The stylet head includes deformable fork 382 tipped with two swiveling grippers 384. Each gripper 384 has a cylindrical boss 386 allowing rotation with respect to fork 382, a non-rotating (e.g., square as shown in
Assembly of the cannula (e.g., within a hollow region) proceeds in a preferably-automated fashion as follows: In
In
With the procedure completed, disassembly proceeds roughly by reversing this process. The fork is compressed and advanced to the most distal ring, and the stylet rotated to match the ring's orientation when interlocked (the angle is stored in memory). The grippers engage the ring, compress it to unlock it, move it distally to swivel it, then retract and release it into a container (e.g., a waste container if the rings are disposable/single-use).
To maximize the reliability of ring interlocking and ensure that tabs enter holes properly, in some embodiment variations in the step shown in
Methods of determining the orientation of the stylet head relative to the distal ring may also be used to ensure that the stylet head is correctly oriented with respect to the ring before an attempt to re-capture the ring by engaging, compressing, and decoupling it is made. Preferably the correct holes of the ring (i.e., those aligned with the minor axis of the deformed ring) are engaged by the grippers, though in some embodiment variations, holes near the correct holes may be suitable, or other holes used. In some embodiment variations, if ring coupling is completed and it is determined that the wrong or sub-optimal hole was used, the ring may be decoupled, re-oriented, and coupled again; this approach may also be used for iterative assembly of the cannula. DASC can be adjusted once assembled to change its shape by simply decoupling and re-orienting rings relative to one another, then recoupling them.
In some embodiment variations, to verify the ring is interlocked before it is released by the grippers, and mitigate the risk of dropping a ring into the patient, the stylet is advanced and the compressive force on it measured (e.g., using a load cell): if the force is less than expected, the ring can be automatically re-compressed, adjusted if needed, and re-interlocked. A similar method may be used in some embodiment variations during disassembly to minimize the risk of dropping the ring: to verify the ring is captured by the stylet head before the ring is decoupled from the next most distal ring, the stylet may be advanced proximally and the compressive force on the stylet measured. In some embodiments, bosses 396 may include relatively long protrusions which capture the ring by its holes even when grippers 384 are not engaged.
Scale models of rings and stylet head similar to those in
One design parameter is the number, size, and shape of the holes (and the corresponding size and shape of the tabs). While eight (or as few as four) are adequate for some cannula shapes, other shapes (e.g., spirals) need more rings (e.g., 20-30 holes) for finer control of ring relative orientation, allowing a smoother shape. Fewer holes allow for stronger tabs such as the design of
Rings can be manufactured from tubular stock by CNC milling, laser cutting, laser/waterjet cutting (e.g., using the LASER-MICROJET® process of Synova S. A. of Ecublens, Switzerland), micro-waterjet, photochemical machining, and other methods. As shown in
In some embodiment variations, for example, those in which DASC grows within solid tissue vs. a liquid or gas-filled space, the fork may be modified to facilitate penetrating, cutting, and/or displacing tissue and to prevent tissue from interfering with the motion of the rings and other components.
Support of flexible stylet shaft 454 before it enters cannula 462, especially when the latter is short (e.g., just the most proximal/base ring or tube) is important to avoid sagging and buckling. Support can be provided by telescoping tubes, bellows, everting tubes, or winding shaft 454 onto a spool as just described.
In some embodiment variations, the stylet head is rotated by means other than twisting the stylet shaft. For example, the head can incorporate female threads with a steep pitch, and a region of the stylet shaft with matching male threads passes through the female threads. By translating the shaft axially, the head would be forced to rotate. Proximal axial translation can be achieved by pulling on the shaft with distal translation achieved by a return spring, or by a lengthening and shortening a small bellows (e.g., Servometer, Cedar Grove, N.J.) using fluid pressure/suction.
In some embodiment variations, procedures needing more than a single cannula can use one set of actuators to assemble several cannulas in sequence. In some embodiment variations, the same actuators used to assemble/disassemble the cannula can be used to manipulate surgical tools inside the assembled cannula, or can steer the cannula's distal end in real time if flexible rings and pull wires are provided.
In some embodiment variations, the edges and corners of stylet and rings can be radiused to minimize the risk of stylet or ring catching while traversing other rings, or excessive friction (e.g., in areas of small radii). In some embodiment variations, the style head axial length is made as short as possible. In some embodiment variations, the most distal portion of the stylet head is designed to easily glide past rings when the stylet head moves distally, while keeping other components away from the inner surfaces of the cannula, where they might get caught; a proximal portion of the head might be used for a similar purpose when the head is moving proximally. In some embodiment variations, the stylet head is coated with parylene or AMC148-18 (Advanced Materials Components Express, Tyrone, Pa.)—a hard, biocompatible, low-friction coating, or provided with a biocompatible lubricant to reduce friction. In some embodiment variations, the stylet shaft is twisted by a known amount while it moves through the cannula to reduce static friction. In some embodiment variations, the stylet head is vibrated (e.g., axially) to reduce friction while passing through the cannula. In some embodiment variations, the shaft is covered with a low friction coefficient (e.g., polytetrafluoroethylene (PTFE)) sheath to make movement easier. In some embodiment variations, a liner, preferably of a low friction coefficient material such as PTFE 15 provided in the cannula to make movement easier. The liner can be extended gradually more distally as each ring is added (e.g., by the stylet or ring pulling it along) and can be withdrawn prior to or during cannula disassembly, for example, by pulling the liner from its proximal end. In embodiments in which the liner is not needed to aid cannula assembly but provided to make the cannula watertight, etc., the liner can be deployed after all rings are assembled, attached to the final/most distal ring, etc., and can be made from materials with higher friction coefficients such as silicone.
In some embodiment variations, the stylet head is pulled forward using a screw-like motion. The head can include a thread-like element (e.g., male or female), which engages projections or another thread (e.g., female or male) that is continuous or discontinuous on the inside of the rings or the inside of a liner. By twisting the stylet shaft, the head is twisted and advances distally or retracts proximally inside the rings. Once the head has moved distally past the most distal ring, it is free to rotate to orient the next ring or to prepare to decouple the most distal ring.
In some embodiment variations, rings may vary in size, shape, type, or function. For example, the most distal ring may incorporate a closed or partially-closed end, as long as the ring can still be deformed to pass through the cannula (unless added separately). A ring may include multiple apertures and mounting surfaces for smaller rings, allowing a single cannula to branch into one or more smaller cannulas, or allowing a steerable catheter or other device to be passed through it in a controlled fashion. The most distal ring and most proximal rings in the cannula may only have tabs but no holes, or vice-versa.
In general, the stylet/ring combination should be as flexible as possible so as to best navigate the cannula when moving both distally and proximally. In some embodiment variations, alternatives to a compression tube may be used to compress and expand the rings. For example, two concentric tubes may be used. One tube is fixed to the stylet shaft (and may be the shaft) while the second is coupled to the grippers through spiral leaf springs such that when the second tube is rotated relative to the first tube in the direction that tightens the spiral, the grippers are pulled radially inwards (and possibly also rotated; this can be compensated). Both tubes can be ACTONE™. Alternatively as shown in the cross-sectional view of
In some embodiment variations, the gripper of
In some embodiment variations, the rings are deformed into a shape which allows movement through the cannula using a mechanism that pushes them outwards rather than pulls them inwards; such a mechanism would normally have the axis of pushing perpendicular to the axis of swiveling (which is normally parallel to the minor axis of the deformed, elliptical ring).
In some embodiment variations, the rings are elliptical in their relaxed/unstressed state and are held circular by virtue of adjacent rings or preferably, a locking mechanism. However, rings dependent on adjacent rings to maintain their shape may not interlock stably. Moreover, the force applied to rings that are more proximal by rings that are more distal and elastically deformed will tend to distort these more proximal rings. It may therefore be preferable that rings have the shape desired for the cross section of the cannula (e.g., circular) while in their relaxed state.
In some embodiment variations, in lieu of four tabs that interlock the rings three tabs may be used; this too may provide stable interlocking of the rings. However, it is challenging to deform the ring into a shape that enables it to pass through the cannula and also allows easy locking and unlocking of the tabs.
In some embodiment variations, in lieu of four tabs just two are provided, preferably parallel to either the major or minor axis of the elliptically-deformed ring. If the tabs and rings both have draft in the correct directions to allow the tabs to be inserted into the holes, the interlocked rings may be stable. However, with only two tabs holding the rings together, the cannula may be weaker, especially when subject to a bending force, compared with one having more tabs. In some embodiment variations, rather than use the tabs to provide stable interlocking in all axes (including shear), the rings are provided with additional features to provide stability that would otherwise be missing. For example, if rings include a smaller diameter tube at their proximal end which fits into the next most proximal ring distal end, stability in shear is provided, and a tab design similar to that of
In some embodiment variations, all the holes or all the holes incorporate a thin (e.g., stamped) region which prevents tabs entering holes from the outside from exiting the holes from the inside, or vice-versa, or comprise holes that are blind. In either case, stability can be achieved with just two tabs.
In some embodiment variations, the tabs can have a more complex form than those shown in
In some embodiment variations, the rings are not stable in shear when interlocked but are stabilized by a separate element, such as a tube (e.g., PTFE) or rod, which is slid incrementally over or through the cannula as rings are added or removed. An internal tube may be preferable to an internal one, as it avoids liquid contact with the rings if liquid is being transported by the cannula, creates a smooth, low-friction lumen through which to pass instruments, and reduces the risk of traumatizing tissue when passing a tube over the cannula. The tube could be advanced or retracted by a separate actuator or intermittently engaged and released by the stylet to advance and retract it.
In some embodiment variations, the proximal end of the ring has male threads and the distal end has female threads (or vice-versa) such that one ring can be screwed into another to interlock them, and also serve to adjust the relative angle of the rings. The axis of each thread should be perpendicular to the surface of the ring at the end that is threaded; thus, the axes of the two threads will not be parallel. In some embodiment variations, even-numbered rings have male threads at both ends or throughout, and odd-numbered rings have female threads at both ends or throughout, or vice-versa.
In some embodiment variations the cannula isn't circular in cross section, but elliptical, and the rings aren't deformed to pass through the cannula, but are elliptical in their relaxed state and simply re-oriented to fit through the cannula. Such rings can only mate with one another in two possible orientations (e.g., forming a zero or maximum curvature pair), limiting the range of possible DASC shapes if all rings are identical. However, if multiple versions of the rings are provided in which the orientation of the wedge angle relative to the ellipse major and minor axes varies, more complex 3-D shapes can be provided if the DASC robotic system is able to select and deliver the appropriate ring at each location.
In some embodiment variations—rather than being deformed into an elliptical shape prior to passing through the cannula (or having an elliptical state in their relaxed state), rings can be circular or otherwise shaped and sufficiently compliant such that when oriented with the ring axis approximately 90 degrees to the cannula axis, the ring is compressed into a sufficiently narrow shape by the cannula itself (i.e., the rings that comprise it) so it can pass through it. When rings are so oriented, their distal/leading surface is curved, facilitating passage and compression. To enhance this effect, rings may be stiff axially but flexible radially.
In some embodiment variations, cannula rigidity may be enhanced by reducing clearances between rings and/or by designing the rings to be mutually preloaded as-assembled (e.g., by tensioning the stylet shaft), and/or by post-tensioning the rings to preload the rings in compression to resist tensile and bending forces using wires running from the most proximal to the most distal ring. If desired, the cannula can also be preloaded in tension, to better resist compressive forces. In some embodiment variations, rings may not be coupled (e.g., by tabs and holes) but simply held together by tension in one or more wires.
In some embodiment variations, a single cannula is comprised of rings that are different from one another. Such variations may include shape, diameter, height, and wedge angle; number, shape, and type of tabs and holes; incorporation of flexural and/or preloading features; and material, among other variations. For example, some regions of the cannula, such as the distal end, may incorporate metallic rings that are flexible due to the incorporation of flexural elements (e.g., like the flexures of
In some embodiment variations, in lieu of the ring shapes of
In some embodiment variations, direct imaging of the cannula as it is being extended can be achieved by incorporating a fiber optic bundle in the stylet, such as surrounding the stylet shaft, or forming the shaft. Alternatively, an imaging sensor such as, e.g., a complementary metal-oxide-semiconductor (CMOS) or charge coupled display (CCD) device, or an ultrasonic transducer, could be incorporated into the stylet, such as attached to the top surface of the swivel block, allowing panning and tilting of the field of view to be achieved by swiveling the block and tilting the stylet shaft, respectively. For example, while the block is oriented as in
In some embodiment variations, DASC can be assembled over a guidewire or other structure, or within a catheter or other structure. To allow for assembly over a structure, the stylet can be designed differently than shown in
In some embodiment variations, DASC rings may be pre-oriented according to the desired cannula shape such that they may be delivered through the cannula and joined to the growing distal end with little or no rotation by the stylet required.
In some embodiment variations, DASC rings may comprise a shape memory allow and transform from one shape into another by heating or cooling. For example, a ring may be circular in axial cross section at elevated temperature, and elliptical in axial cross section at a lower temperature. For example, the ring may remain relatively cool while it is transported through the cannula, but upon exiting and coming into contact with body tissue or fluid, the ring may warm and transform its shape. A source of heating or cooling may also be used; for example, the stylet may be heated or cooled and by contact with a ring thereby heat or cool the ring.
In some embodiment variations, DASC rings comprise different numbers of tabs and holes, and transform into shapes that are not substantially elliptical. For example, a ring may transform into a rounded triangular shape having tabs at the vertices and at the midpoint of each side, and couple with another ring (e.g., circular) by deforming such that the tabs at the vertices enter holes in the other ring from the outside, and the tabs at the midpoints enter the holes from the inside.
In some embodiment variations, DASC rings are designed for low radial stiffness but high axial stiffness. For example, a ring can be corrugated or scored (e.g., by etching, milling, laser engraving) so that it deforms easily into an ellipse. The corrugation and/or scoring can be very localized since the major and minor axes of the ellipse are normally the same for all rings: as few as two scoring lines aligned with the major axis can be sufficient.
In some embodiment variations, the proximal end of DASC is outside the patient's body, while in other embodiment variations, the proximal end is within the patient's body, for example, attached to a rigid tube, flexible catheter (e.g., one that is anchored), anatomical structure such as bone, implant, etc.
In some embodiment variations, the holes in the rings are blind so that the rings may form a substantially leak-proof conduit when assembled. Alternatively, the holes may be through holes, but a liner is affixed (e.g., by bonding) to the rings on the interior and/or exterior to provide sealing. To improve sealing, the rings may be made from a soft material such as an elastomer, or have elastomeric mating surfaces. In some embodiment variations, rings made from a hard material such as metal alternate with rings made from a soft material such as silicone rubber, to provide sealing. In some embodiment variations, the soft rings are essentially gaskets which are individually placed during DASC assembly or attached to rings on either the proximal or distal faces, or both.
In some embodiment variations in which DASC remains in the place, e.g., as an implant, DASC can be detached once deployed, by methods including mechanical decoupling, fracturing, electrolytic dissolution, melting, and so forth.
18th EmbodimentA corrugated, bellows-like tube may be provided initially in an axially-compressed state, compressed configuration. The tube may be extended by advancing the distal end distally, carrying with it the folded corrugations, while allowing corrugations to unfold and lengthen from the proximal end. By varying the extent of unfolding at different circumferential locations, the direction in which the distal end moves can be controlled, steering the tube as it lengthens.
19th EmbodimentAn everting flexible tube/cannula as in the 8th Embodiment, comprised of a material that can be stiffened locally can be deployed into a cannula of complex 3-D shape by incrementally or continuously feeding the inner walls in a distal direction by an amount that may differ circumferentially, and stiffening the tube locally upon its eversion to form outer walls. For example, the tube may comprise a photopolymer (e.g., a photopolymer-impregnated tube of carbon or glass fiber) that is initially flexible but which is rigidified by exposure to ultraviolet or visible light, e.g., produced by a ring-shaped light that surrounds the inner walls at the growing distal end. Materials stiffening due to cooling, evaporation, chemical reaction, etc. can also be used. The resulting outer walls are thus rendered stiff, retaining the local curvature, if any, produced when the inner walls were everted and passed the ring. Unless the stiffening is reversible, such a cannula may be permanently deployed. If light is used to rigidify the tube, it can be shielded by suitable design of baffles from those regions which have not yet been everted and given the desired direction and radius of curvature.
In a similar manner, the outer walls of a braided everting tube (e.g., made from superelastic nickel-titanium) may be locally stiffened and locked into position once formed by locking the wires of the braid to one another, preventing relative motion. For example, selected wires may be resistance or laser welded to one another on the outer walls; this can be done as the inner walls are fed distally by an amount that may differ circumferentially, and everted to form the outer walls.
20th EmbodimentThe 20th Embodiment shares some similarities with the 7th Embodiment above.
As shown in the elevation view of
In the 3-D views of
1. Swivel the ring (by translating the swivel wire distally, relaxing tension on it, etc.) until its axis is substantially perpendicular to the stylet axis and expand the ring by rotating the flexible shaft (e.g., clockwise). These steps may be performed in either order. The loop and ring remain expanded without further involvement by the flexible shaft; however, the flexible shaft must translate along its long axis to allow swiveling to occur. This translation may be actively provided or it may be passive. If passive, the shaft can be elastic, or have an elongatable, torqueable section (e.g., telescoping), or its actuator (e.g., a motor) can be mounted so as to allow movement, for example. Translation of the shaft is also important when mating the ring to the next most proximal ring, since the swivel block may need to swivel slightly to ensure that the proximal surface of the ring to be mated is parallel to the distal surface of the next most proximal ring.
2. While the ring is expanded, translate it and the stylet head through the cannula from its proximal to its distal end.
3. Pull the swivel wire to swivel the ring until its axis is substantially parallel to the stylet axis and rotate the stylet around its longitudinal axis to orient the ring as required. These steps may be performed in either order, and rotation may be accomplished prior to translating the ring.
4. Move the stylet and ring proximally to mate the ring with the next most proximal ring and rotate the shaft (e.g., counterclockwise) to allow the ring to regain its unstressed, circular shape while allowing the tabs to enter the holes in the adjacent ring. Further rotate the shaft to decouple the ring from the stylet head, allowing the latter to be returned proximally (after swiveling) to fetch another ring if needed.
Stylet heads such as those of
While in some embodiment variations rings may be themselves magnetized along the ring axis and thus are attracted to one another, in the embodiment shown, relatively small rectangular magnets (e.g., NdFeB, not shown) are fastened into slots in the mating surfaces of the rings. All the magnet poles facing outwards from the proximal faces of the rings are of one polarity (e.g., North) while all the magnet poles facing outwards from the distal faces of the rings are of the opposite polarity (e.g., South), thus ensuring that rings are attracted to their immediate neighbors. Since there are multiple (here, eight, but many more are possible) magnets distributed around the faces of the rings at substantially equal angles to one another, it is possible to join one ring to another with multiple (e.g., eight) orientations, thus achieving the same effect of controlling the local curvature and direction of the cannula as if one used rings with interlocking features such as tabs and holes. The rings are equipped with diametrically opposite wide and narrow holes to engage a stylet head such as that shown in
In some embodiment variations, the magnets are not as small as shown or necessarily flush with the inner and outer surfaces of the rings, and may be joined to the inner or outer surfaces of the rings, with no slots required. In some embodiments, magnets may serve as an aid to orienting rings relative to one another, but the mechanical strength of the joint is provided in large part by interlocking elements such as tabs and holes. The use of magnets on rings can apply to other embodiments such as the 17th Embodiment, as well as the 20th Embodiment.
Continuous distal assembly and disassembly:
The distally assembled cannula, or tube, described in the 14th Embodiment can grow in a continuous manner as material in strip form is delivered continuously to its distal end through its lumen. The distal portion of the strip forms the proximal end of the tube and the proximal portion of the strip forms the distal end of the tube as the assembly process progresses. The strip forms a series of approximately helical windings in which a section of the strip is joined to another section of the strip, together forming a cannula. A winding is assumed to be a full 360° of rotation of the strip around the longitudinal axis of the cannula; however, the beginning and end of a winding (i.e., the 0° and 360° locations) may be somewhat arbitrary. In regions where the cannula is curved, the windings may not be parallel to one another. This is distinct from approaches such as those of the 17th and 20th embodiments, which achieve growth intermittently as each ring is added. Continuous (or even quasi-continuous) growth offers a number of potential benefits over intermittent growth, such as a) much faster assembly and disassembly (since there is no need to grasp and swivel a ring, transport it over a distance, swivel and release it), enabling a faster process and making very high aspect ratio (length to diameter, e.g., 300:1) cannulas feasible; b) no risk of a dropped element (e.g., ring); c) reduced alignment requirements; d) less costly (e.g., reel-to-reel) manufacturing processes and potentially less costly materials (e.g., stainless steel versus superelastic nickel-titanium); e) more compact storage of material (e.g., on a spool); f) the ability to adjust the cannula shape after assembly in some embodiments, allowing very rapid motions if permitted by the available working space; g) a stylet which remains distal during assembly and disassembly, facilitating real-time monitoring of the cannula growth direction and the assembly/disassembly process (e.g., helping with alignment, identifying problems); and h) in some embodiments, the ability to produce a cannula of different diameters, or of variable diameter (e.g., tapered).
In the 14th Embodiment, a winding (i.e., a section of the strip) may be joined to another winding with a variable amount of overlap, thus modulating the local effective width of the strip, as is required to change the growth direction (i.e., the local radius and plane of curvature) of the cannula. Whereas varying the amount of overlap is one approach to varying the effective width and is used in some embodiments for this purpose (and can also increase cannula strength and stiffness), in other embodiments each winding of the strip is joined with a non-varying overlap (e.g., in an edge-to-edge fashion) to its proximal neighbor, and the actual local width of the strip is modulated. Both approaches may also be used in the same cannula.
In assembling a cannula as in
A strip with parallel edges can be wound around a straight cylinder to form a helical winding, and no distortion of the strip is required. A strip having one sinusoidal edge can be wrapped perpendicularly (i.e., not helically) around a cylinder to form a ring that is wedge-shaped, akin to the rings of
To further elaborate on methods for joining one section of the strip to another—some easily reversible and some not easily reversible—as described above in connection with
In some embodiments of a continuously distally assembled/disassembled curved cannula, adjustment of the local overlap or width is performed as the strip is being wound into a cannula: i.e., the adjustment is performed at one circumferential location at a time before or as the winding is joined to its proximal neighbor. In some embodiments, the adjustment may be performed after one or more windings has been already created. For example, a winding (assumed to be 360°) for example with parallel strip edges to produce a straight direction of the cannula can be formed and joined to the adjacent winding, and then the direction can be altered into a curve by making the winding wedge-shaped after it has been fully formed and joined. If the stylet needs to temporarily stop winding the strip to grow the cannula while making this adjustment, the result is quasi-continuous growth, since there are brief pauses.
A stylet of suitable design, translating and in some embodiments, rotating inside the cannula as it grows, can be used to attach one winding of the strip to its next-most distal (i.e., proximal) neighbor. The stylet can also be used to modulate the overlap of one winding with respect to another, and/or the local width of the strip. The stylet may be moved by proximally-located motors and other actuators much as with the stylet of the 17th Embodiment.
In some embodiments, the cannula may be formed from a set of strips (e.g., joined end-to-end or side-to-side) rather than from a single strip. Materials suitable for the strip or sub-components therefore for a continuously distally assembled/disassembled curved cannula include but are not limited to metals such as stainless steel, nitinol (nickel-titanium, e.g., superelastic), titanium, vanadium, aluminum, nickel, tantalum, zirconium, chromium, silver, gold, silicon, magnesium, niobium, scandium, platinum, cobalt, palladium, manganese, molybdenum and alloys thereof, and zirconium-titanium-tantalum alloys, as well as polymers such as thermoplastics, thermosets, elastomers, etc. Examples include polycarbonate, polypropylene, polyethylene, acetal, nylon, fluoropolymers, thermoplastic elastomers, silicone, natural rubber, vinyl, and latex. Amorphous materials such as glass and amorphous metals, as well as ceramic materials may also be used.
21st EmbodimentReferring to the 3-D views of
As shown in
As shown, the overlap between sections 790a and 790b is at its minimum, while that between sections 790b and 790c is at its maximum. Intermediate amounts of overlap are also possible, depending on polygon orientation. In some embodiment variations, rather than a polygonal wheel with bosses to lock its orientation, a smooth but high-friction wheel may be used, or a gear or sprocket may be used with one or more tabs which engage the teeth. If the wheel is smooth but tapered to match the circular cutout, then the natural tendency of the strip to straighten itself (if not fully plastically deformed) may force one section of the strip against the wheel and push it more tightly into the cutout, frictionally preventing it from rotating in the assembled cannula.
22nd EmbodimentIn
As shown in
When two adjacent sections of strip are brought into proximity by the stylet, as they would be when growing the cannula, the tabs 834 in one section can fit into the holes 832 in the adjacent section as shown in
The screw 820 of the adjuster 844 may be rotated by engaging its thin gear 826, for example with a drive gear as shown in
It is preferable in many applications that the lumen of the cannula be as unobstructed as possible. Thus in
In some embodiment variations, rather than using a screw with a tip that snaps into one band, a screw with both left and righthand threads (e.g., on either side of a central gear) can be used, with nuts provided for each thread of the screw. In some embodiments, rather than have a screw adjust the width of the strip and use means such as tabs and holes to interlock adjacent windings of the cannula, the screw may be used to adjust the relative overlap of one winding with another adjacent winding, and connect them together. In some embodiment variations, other than using tabs and holes to join adjacent strips, other means can be used, including all of those mentioned above. The same is true of all of the continuous distally assembled cannula embodiments.
23rd EmbodimentPulley-like wheels 908 are provided in some embodiments which ride along the upper rail 904 and/or lower rail 906. The wheels 908 roll on shafts (not shown) supported by a stylet, and the distance between the shaft axes can be changed continuously. For example, the stylet may comprise two coaxial tubes, which can be relatively translated along the tube axes so as to vary this distance. When the distance between the axes (and wheels) is increased, the expandable region—comprising material perforated (see perforation 910) with a diamond-like or other pattern as is known in the art of expanded metal and stent design—expands, plastically or elastically deforming the metal, and thereby increasing the width of the strip in the region. Not shown as gaps or cuts in the rails which allow the strip to contract longitudinally as it expands transversely. Such gaps, which in some embodiment variations may be oriented roughly parallel to the cannula axis or transversely, can also allow the strip to bend more easily, and may also be provided in the expandable region 902. Thus, as the wheels move along the strip, positioning each winding of the cannula adjacent to a more proximal winding and connecting the two together (e.g., using tabs and holes, not shown), the local strip width may be changed. In some embodiment variations, the expandable region is held in its final configuration by elements which are added to stabilize it against applied forces, such as a material which fills the perforations, and in such variations, the expandable region may be at least in part elastically deformed. In some embodiment variations, rather than push the two rails apart, the rails can be pushed together to reduce the width of the strip, or the width can be increased or decreased from an initial value.
24th EmbodimentIn some embodiment variations, instead of interlaced fingers, a ratcheting mechanism may be provided such that when the two bands are pulled apart or pushed together locally, the new width is maintained by the mechanism.
26th EmbodimentThe cams 954a,b may be initially located (e.g., by detents, a pivot, or clamping pressure) in between the cuts 952, so that they do not interfere with flexing of the channel. Once the channel is curved, the straight portion of the channel wall and the corner where that portion meets the curved portion, can press against the cams, helping to stabilize them in their desired orientations. Thus the orientations of the cams 954a,b may best be set before fully flexing the strip. In some embodiment variations, the cams 954a,b are retained in their orientations by teeth along their edges which fit into teeth within the C channel 950. In some embodiment variations, the cams 954a,b may be provided with flats along their edges to improve their rotational stability (e.g., they may be polygonal, but not with equal distances between opposite flats).
In some embodiments, rather than using a C-shaped channel 950, a strip with an expandable region as in
As previously described, a continuously distally assembled/disassembled curved cannula can use strips 982, 984 which overlap by variable amounts, or strips having variable widths (not depicted).
In some embodiment variations, the staples 992 are not separate pieces, but are attached to the band or strip and are deformed (e.g., bent) so that their prongs enter suitable holes 990; this can be done by a mechanism on the stylet.
28th EmbodimentBy replacing the nut plate with a cam such as that in
In the 3-D view of
In some variations of this and the 22nd Embodiment, instead of a screw 1002 that changes the separation between the bands, the stylet can locally separate the bands by the required distance (e.g., using two coaxial graspers) and engage a locking mechanism such as a cam acting on a tab or rod fixed to one band and overlapping the other band) to set the distance between the bands. A less easily-reversible, variable-distance connection between bands can be made using welding, adhesives, and the like.
30th EmbodimentPedestal 1036 may be of a different form than that shown in
In the assemblies of
As shown in the 3-D sectional views of
It is generally necessary to have a structure for the stylet to grasp and manipulate the strip during assembly and disassembly of the cannula. In the case of a strip of irregular shape such as that of the 30th Embodiment and in other embodiments, a track (e.g., a female dovetail 1038 as shown) may be provided on the inside surface of the strip as shown in the 3-D view of
The positions of the sliding wedges 1040 may be set in advance, while the strip is being fed to the distal end of the cannula, or while the strip 1050 is being formed into windings of the cannula. For example, while the strip 1050 is being delivered, rollers, arms, or other elements (e.g., attached to the stylet) can separately drive the sliding wedges 1040, but at different relative speeds, thus causing sliding wedges 1040 to slide relative to the fixed wedges 1030, which are attached to the body of the strip 1080 (in
To reduce the bending stiffness of the strip of the 30th Embodiment, partial-depth cuts 1076 (or cuts which pass entirely through the strip) may be provided as shown in
In some embodiments, windings based on sliding wedges such as wedge 1040a of
In some embodiment variations, the strip can comprise at pair of facing surfaces of which at least one is ramped. A ball, wheel, or other shape can roll or slide between these surfaces, pushing them apart, and thus altering the width of the strip. If the angle of the ramp is shallow, friction may retain the ball or other object in position, but detents can also be provided, or the object can be secured in place by other means (welding, adhesive, fastener, etc.).
32nd EmbodimentAs shown in the Figures, all tabs are in the same notches on the plate (the center notch). However, the notch that is used can vary along the length of the strip, and thus the strip width can vary along its length. The angle of the diamonds (or other pattern) comprising the expandable region may be steeper than in
A continuously distally assembled/disassembled curved cannula having a shape that is known before it is deployed can be generated using a strip that is prefabricated with a variable width (e.g., by laser cutting or photochemical machining), according to a computerized design. Then, assembly is merely a matter of re-orienting the strip and attaching the edges of one winding to another.
Stylet for a continuously distally assembled/disassembled curved cannula:
In some embodiments, instead of a guide, the strip 136 (in
The strip must of course be flexible enough to allow re-orientation and deformation into the shape of a winding, and may incorporate full- or partial-depth cuts or be scored approximately parallel to its width or to the cannula axis at intervals to increase flexibility as described above. Or, in some embodiments, the strip may be generally flexible, but may include ribs or other thickened regions oriented similarly to the cuts and arranged at intervals to increase its stiffness in the width or cannula axis direction. Each winding of the cannula may be polygonal, with flat or curved faces, instead of smoothly circular, if the strip flexes primarily in cut regions, or between ribs. The strip may be designed to be elastically deformed or plastically deformed. If elastically deformed, the tendency of the strip to straighten itself can be helpful in some embodiments to provide a preload that interlocks the strip with itself. If plastically deformed, the strip can nonetheless be actively bent as needed to form the winding. Selective annealing (e.g., by laser) may be used in some embodiments to make certain regions of the strip more easily deformed than others. Especially if the strip is to remain only elastically deformed, then unless the strip is made from a superelastic material such as nickel-titanium, the deformation should be minimized.
In some embodiments, strip 1136 does not travel through the cannula the entire distance in a substantially flat shape as suggested by
In
If the strip is at least partially plastically deformed when re-oriented and made to form a winding of the cannula, then during disassembly the stylet can assist in straightening it. The stylet can also serve to pre-bend the strip so that when formed into a winding, the forces tending to straighten it out are increased, which can help increase the preload that joins one winding stably to another.
As discussed in the various embodiments of a continuously distally assembled/disassembled cannula, the stylet can also be used to adjust the overlap of one winding with respect to another, and/or the local width of the strip, and can include various provisions for this that are not shown, such as translating and/or rotating elements which engage the strip. Joining the strip to itself and adjusting its curvature can be performed simultaneously in some embodiments, while in other embodiments it is sequential. During assembly of the cannula, as the strip is joined to itself, it is pulled distally along the cannula, either actively or passively.
If the stylet head is provided with features which engage the already-wound strip, the stylet can in some embodiments be pulled distally by simply rotating it from the proximal end. For example, if the strip contains a female dovetail 1038 like the strip 1050 of
A strip of constant width or constant overlap forming a straight cannula will follow a helical path with a constant pitch. A curved cannula, however, may have a variable pitch. Thus in some embodiments the ratio between the travel of the stylet along the cannula axis (which may be curved) and the number of stylet rotations may vary from location to location along the axis. In some embodiments, the location of the stylet along the cannula can be measured and used as feedback. For example, the stylet may include an optical sensor (e.g., a miniature camera such as those made by Medigus Ltd. (Omer, Israel) that detects features on the strip such as gaps and holes, regularly-spaced markings on its inside, etc. Mechanical sensing may also be used.
In some embodiments, the stylet may have centering rollers, wheels, or spockets, or gears (e.g., 3-4 rollers which may have an elastomeric surface, sprockets which engage holes in the strip, or gears which engage corresponding teeth on the strip) which engage the inside diameter of the cannula and which rotate actively (i.e., driven) or passively to propel it up and down the cannula. The stylet head or portions thereof may rotate as needed to assemble or disassemble the cannula, or the entire stylet may rotate. If the rotation plane of the rollers is arranged to be approximately tangent to the roughly helical shape formed by the strip, the rollers may be driven to provide simultaneous axial and rotational motion of the stylet, or if the rollers turn passively as the head is moved, then they may turn with minimal friction. In some embodiments, the stylet may be centered within the cannula by balls, omnidirectional wheels, or low-friction material such as PTFE.
Overall, by rotating the stylet shaft, the stylet head can assemble the cannula by wrapping the strip and joining the strip to itself, adjusting the local overlap and/or width of the strip as needed, while the stylet moves distally through the growing cannula. At least one actuator can be provided to adjust the local strip overlap, width, etc. Especially for small diameter cannulas, the force supplied by this actuator can derive from pulling on the proximal end of a wire which is fed through the center of the stylet shaft and connects to an appropriate mechanism on the head.
In some embodiments, a winding may be connected to the adjacent winding just proximal to it while the winding is in a neutral (e.g., parallel top and bottom edges) state. After this, it can be plastically deformed into the desired wedge shape by the stylet and then released, or elastically deformed and locked into the wedge shape by the addition (or movement) of locking elements. In some embodiment variations, additional leverage may be gained when deforming the winding by arranging for the stylet to exert forces at a distance from the winding to be deformed, using the cannula as a lever arm to increase the moment.
In some embodiments, the stylet may incorporate sensors (e.g., at its distal end, or head) which allow assembly and/or disassembly to be monitored and controlled, and/or which allow the growth direction of the cannula to be determined based on images of the surrounding environment. Thus for example a small imaging device such as a side-looking or forward-looking camera may be incorporated into the stylet head, or a fiber optic imaging bundle. In some embodiments, the stylet may incorporate elements which allow a liner (e.g., to make the cannula fluid-tight) to be pushed or pulled through it, or otherwise deployed. In some embodiments, at least one cannula may be assembled within another, either sequentially or simultaneously, to create at least two lumens; in some embodiment variations, the apertures in one cannula can be substantially blocked by regions of an adjacent cannula, providing less porosity overall.
In some embodiments, rather than using the stylet to only assemble and disassemble the cannula, it can be left in place, working in concert with the cannula (i.e., the continuous, wound strip) and allowing more rapid changes in overall shape (further extending distally, retracting and extending in a new direction, etc.). Indeed, there are procedures that must be performed using the cannula while its shape is still expected to change. For example, the stylet may incorporate sensors such as a forward-looking camera so that the stylet/cannula combination can be used for inspection and surveillance. In some embodiments, the stylet may incorporate at least one lumen (e.g., fluid-tight), which allows various functions without having to withdraw the stylet from the cannula (which would provide a larger lumen, of course). For example, instruments, tools, and sensors may be passed through the stylet lumen. Or, fluids such as air or jetted water may run through the stylet lumen towards the distal end to dislodge dirt, soil, and debris in a search and rescue application, or to improve visibility if the stylet includes a camera at its distal end. Fluids (e.g., delivered through the stylet lumen, or through a hose, and directed radially) can also be used to keep the strip clean in areas containing features which are used to join windings to one another. For example, in a medical procedure saline may be transported toward the distal end in order to provide irrigation and maintain a clear field. A stylet lumen may also be used to aspirate material from the distal end (e.g., blood and loose tissue in a medical procedure, dirt, soil, and rocks in a search and rescue or underground/underwater tunnel boring operation).
35th EmbodimentThis is further illustrated in the photograph of
It should be noted that the cannula of
If all links 1206 (in
Links 1206 (in
The 3-D views of
Since there are two rows 1218a,b wires 1216 (in
In some embodiment variations, only one wire 1216 (in
A strip such as that of 1212, if made from metal (e.g., 301 stainless steel), can be manufactured, for example, using photochemical machining (e.g., reel-to-reel) or by stamping, with the wires fastened to it by welding (e.g., laser) or other methods. Since some windings must be non-parallel if the cannula includes curved regions, in some embodiment variations, welding is confined to a portion of wire 1216 (e.g., the center) to allow the wire to rotate slightly to accommodate the non-parallelism. Alternatively, wire 1216 may be replaced by one or more balls (e.g., distributed transversely (perpendicular to the length of the strip)) or compliance can be incorporated into the fingers (e.g., each may be twisted in its center region so as to be more flexible in the circumferential direction).
In some embodiment variations, slots 1220 are significantly longer than wires 1216 to allow for circumferential misalignment and easy of assembly. In some embodiment variations, slots 1220 are radiused to reduce stress concentrations. In some embodiment variations, fewer but wider fingers 1214 are used, with correspondingly fewer and wider slots 1220. In some embodiment variations, other approaches for coupling may be used in lieu of or in additional to these, such as magnets or a liner in combination with features which prevent relative shear between windings (e.g., bent tabs which fit into slots). In some embodiment variations, fingers 1214 can be provided with a lip, ridge, or tab (not shown) or similar features, or merely an extension of fingers 1214 beyond wires 1216, which enable the stylet to pull the wires free of the slots during disassembly of the cannula. In some embodiment variations, a tapered blade or similar can be inserted by the stylet between fingers 1214 and strip 1212 on the adjacent winding, or under the lip, ridge, or tab, to help separate the windings during disassembly.
If the strip is stamped, then reentrant features similar to those achieved by attaching a wire can be achieved. The 3-D views of
In some embodiments, strips can be interlocked for this and other embodiments by incorporating features that can only be interlocked with one another when one strip is bent and/or twisted with respect to another. Then, once the features are interlocked and the section of the strip in which they are located becomes unbent and/or untwisted to form a winding, the strips cannot be separated until the cannula is disassembled, at which time the strip is free to bend and/or twist again.
In general, features such as wires mated with slots, or stamped features such as those of
Assuming that
The 3-D view of
A second slot 1234 is provided on the wedge to engage ball 1236, itself having a reentrant surface during the process of assembling the cannula (i.e., forming windings from the strip and joining it to itself), by elastically snapping slot 1234 of wedge 1224 over ball 1236 (e.g., by action of the stylet, especially if wedge 1224 is facing the inside surface of the cannula). This may most easily be done when ball 1236 is not near the ends of slot 1234. Ball 1236 and wire 1228 may be fastened to band 1226 by laser welding, for example. In some embodiment variations, slot 1234 may be wider in one area to facilitate entry of ball 1236.
Several (e.g., three) bosses and wedges are provided per winding, with the bosses typically equally spaced.
Adjustment of wedges 1224 can be accomplished by pushing or pulling on wide edge 1236 or narrow edge 1238, or on other features. Adjustment can be done by the stylet (e.g., the stylet head) during assembly of the cannula, or can be done while the strip is en route to the distal end of the cannula, for example. Adjustment can create significant width changes: in the design shown, the strip width can be increased from a minimum value by over 30%. Since wedges in general will not be set to the same height (unless the cannula is to be straight in a region), the strips will not in general be parallel. However, each strip can rotate slightly at ball 1236 around its neighbor, allowing for non-parallelism.
In some embodiment variations, the mechanism for securing the position of wedge 1224 when the strip is not part of a winding (e.g., travelling through the lumen of the cannula) is provided. A detent produced by a small deformation of the wedge and/or strip can be used, for example for this purpose, and may be located at one end of travel for wedge 1224, centrally, or elsewhere. For single-use cannulas, a light adhesive, etc. may be used to secure the wedge. The force required to slide the wedge should of course not be so high that it interferes with sliding it when required.
Once the position of wedge 1224 is adjusted and the strip is curved into a winding, the increased friction between wedge 1224 and strip, in combination with the relatively shallow angle of slot 1230, will stabilize wedge 1224 against unwanted movement. Adjusting of wedge 1224 may be accomplished in some embodiment variations by a rotating or sliding finger or other element on the stylet which engages wedge 1224, e.g., at edge 1238 or 1236. If the tangential velocity of the finger is higher or lower than that of the stylet head, for example, wedge 1224 will move relative to boss 1232, either increasing or decreasing the effective width of the strip in the region of wedge 1238.
In some embodiment variations, in lieu of a single wedge 1224 associated with each boss 1232 a pair of wedges is provided which slide in opposite directions (toward or away from one another) to adjust strip width. In some embodiment variations (of this and other embodiments such as the 30th Embodiment), in lieu of slots and wires or balls, the edges of bands and wedges may be folded over to form a J-shaped “hem”, with the hem on one part hooked that of another, thus providing a sliding coupling. One part may also be deformed after the two parts are joined, to prevent the coupling from separating. In some embodiment variations, ball 1236 may be located on wedge 1224 and slot 1234 may be located on boss 1232.
Continuously Distally Assembled/Disassembled Curved Cannula System:
As shown in the 3-D view of
As shown in the 3-D view of
As shown in the 3-D partial sectional view of
As stylet head 1258 rotates, it also must translate according to the local pitch of the windings. In a curved section of the cannula, this varies around the circumference: being smaller on the inside than on the outside of the bend. Moreover, it can be difficult to push the stylet from its proximal end without it buckling (though in some embodiments centering devices such as those of
For sprocket 1266 to remain reliably engaged with sprocket holes, the shaft of sprocket 1266 may be spring-loaded in some embodiments, or head 1258 may be pressed in the direction of sprocket 1266, or at least kept at a substantially constant distance from windings such as winding 1270. In some embodiments, head 1258 is maintained concentric with the cannula. In some embodiments, distance may be maintained by providing other elements on head 1258 such as balls 1264. Balls 1264 may be rotating or non-rotating; in the latter case balls 1264 may rotate in sockets within head 1258 as head 1258 rotates and translates. If one sprocket 1266 is used as shown, two or more balls 1264 may be used to maintain the position of head 1258 within the cannula. In some embodiments, in lieu of balls, rollers, wheels, or other devices may be used.
In the case of a strip designed similarly to that of
If used, pull wire 1306 (similar to pull wire 1274 of
If required, components such as the stylet with pull wire 1306, etc. can be completely withdrawn from cannula 1246 without disassembling the latter, e.g., to provide a clear lumen for inserting devices and other payloads. An actuator to temporarily displace any console components that obstruct access may thus be needed. Also, to withdraw the stylet may require an additional actuator to decouple strip 1292 from the stylet (e.g., by retracting the sprocket and head-centering balls), allowing the stylet to be pulled out.
In some embodiments, payloads may be pushed or pulled by the stylet from one end of the cannula to another as the stylet advances or retracts (either during the assembly or disassembly of the cannula, or at other times). In some embodiments, payloads may be contained within capsules or otherwise provided with features such as sprockets which engage sprocket holes on the strip (e.g., the same ones used to translate the stylet). Such payloads can be transported through the cannula (with the stylet withdrawn) by causing them to spin (e.g., driving them with a rotating torque coil). In some embodiments, the stylet can leave sensors, actuators, or other devices at the distal end of the cannula and then itself withdraw. Wires can be then trailed back from the device, or the strip may provide electrical connections to the device by having wires embedded within it or insulated electrical traces on its surfaces. Of course, the device can also be wireless, including having its own power source, or the ability to harvest energy.
In some embodiments, multiple, separate cannulas can be assembled from a single strip, in which case, the console may include a cutter for strip 1292. In some embodiments, reel 1290 may be easily replaceable, and may be in the form of a replaceable cassette, allowing more strip to be added added to the cannula system. In some embodiments, a short working distance, side-looking camera (or simpler sensor) in the stylet head can be used to verify or facilitate the motions of the strip and stylet required to join one winding to another or to separate the windings. In some embodiments, it may be useful to know the precise shape of at least part of the cannula in real time, so that this data can be used for error correction: modifying the trajectory as the cannula is assembled. This may require proprioceptive sensors such as strain gauges or electromagnetic position/orientation sensors. In some embodiments, navigational sensors such as a camera may be required for a human operator to steer and navigate the cannula through obstacles in the environment, and may also be needed for the task at hand (e.g., inspection).
Low-level mechanical control of the cannula can be accomplished by software to interpret the growth path (e.g., specified by an operator in real time, or ahead of time) as low-level actuator commands (e.g., moving sliding wedges to specific positions, rotating the stylet at a particular speed). However, control of a distally-growing cannula, especially if very high aspect ratio, can be challenging. If not for tolerances, clearances, and material compliance, and if structural loads were non-existent, the evolving cannula shape should be fully deterministic. Thus reaching a known target with the distal end, for example, would be purely a matter of navigation or path planning, coupled with automated deployment. However, this is not the case, and the cannula shape and position of the distal end may deviate from what is desired unless compensated. With high length-to-diameter ratios and distal growth, loading of the cannula by body and contact forces can change dynamically as the cannula grows. While this is less of a problem in microgravity or in buoyant underwater applications, inertial and (if the cannula is immersed) viscous forces may still have significant effects.
The shape of the entire cannula may matter in some contexts (e.g., surgical, to minimize tissue trauma), as well as the position of the distal tip. The desired cannula shape may be achieved and maintained by model-based control, in which the effect of forces on the cannula are simulated (with input from test data) and the shape estimated.
With some designs of strip (e.g., those of
Convergence of the distal end of the cannula on a desired target can also be achieved in some embodiments by modifying the curvature settings of winding not yet deployed, ideally doing so in an iterative process of sensing cannula shape and/or distal end position, and re-calibrating.
In some embodiments, the feasibility of target attainment given current constraints (e.g., target position, undeployed cannula length), current distal position and orientation is important to determine. For example, an operator may need to decide whether to retract/disassemble the cannula partially and attempt to reach the target by extending it again along a new trajectory. This determination should include a safety factor that takes into account errors and expected additional proximal deformations as the cannula continues to extend.
Interlocking elements such as tabs 958 and holes 960 need not be flat as shown in
In some embodiment variations, ball 1166 may protrude further from winding 1162, providing an undercut which winding 1172 can hook onto. In some embodiment variations, e.g., ones in which winding 1162 is not adequately preloaded against winding 1172, hole 1170 in winding 1172 may have edges which are compliant and thus can allow winding 1172 to “snap” over ball 1166.
In some embodiments, rather than using a ball 1166 and a hole 1170 as in
In some embodiments, magnets (e.g., NdFeB) attached to the strip may be used to join windings to one another, or to assist with alignment and engagement of windings which are joined by other methods. For example, the strip may be provided with magnets spaced regularly along or near their edges, with one pole (e.g., north) facing away from the strip and the other facing towards the strip. When two sections of the strip and then brought near one another to form windings, the magnets will attract one another.
In some embodiments of a continuously distally assembled/disassembled cannula, a cable or similar tension member, or a strut or similar compression member, can be used within or outside the cannula to stiffen it, e.g., by preloading windings against one another. In some embodiments, the stylet, if left within the lumen, can serve this function, while in some embodiments, a member can be inserted and connected to the windings (e.g., by the stylet after the assembly process) and removed (e.g., by the stylet prior to disassembly).
In some embodiments and applications, the stylet does not remain within the cannula after assembly, but is withdrawn (e.g., proximally) to allow full access to the lumen. In some embodiments and applications, the stylet does not significantly block the lumen, or access to the lumen is not required, and may remain inside the lumen. If the stylet has been removed or repositioned, it may be re-inserted or repositioned to allow disassembly of the cannula, or (if the design permits it) adjustment of the cannula.
Instead of a DASC instrument that is substantially constant in diameter as has been illustrated herein, in some embodiments DASC based on rings, continuous strip, or other approaches can have a tapered shape (e.g., smaller at the distal end). If the taper angle is relatively large, rings may be transported through the cannula without the need to compress and swivel them to fit, or require less compression and/or swiveling.
In some embodiments, multiple DASC devices may be used simultaneously in a procedure, either with the distal ends in different target regions or in the same target region but (e.g., with different approach angles). For example, two DASC devices in the same region with different approach angles can allow for triangulation useful in suturing, tissue, retraction, etc.
Instead of transporting material to the distal end of DASC through a lumen to extend it, in some embodiments material can be transported over (on the outside of) DASC, or alongside DASC, e.g., using DASC as a rail or guide for the material transport. In some embodiments, material necessary to extend DASC is obtained from the environment.
In some embodiments, the DASC lumen can be subdivided by inserting tubing after the desired shape has been assembled, or gradually as it is being assembled. For example, four tubes may be passed through the cannula: one for irrigation with saline, one providing a working channel for an instrument, and one providing a channel for an endoscope, and one providing a channel for a fiber optic illuminator. The remaining space in the lumen can then be used for aspiration.
In some embodiment variations, to minimize the time required for the stylet to connect a ring and/or make a long trip back to the ring stack to pick up another ring (or drop off another ring if disassembling the catheter), the rings can be stored more distally within the gradually-extending cannula. For example, rings can be held in a compressed state (e.g., within a tube, one behind the other) located inside the cannula. Such rings could be pushed out by a plunger. Or, rings could be held within a frame designed to allow the grippers to engage them and separate them from the frame: the rings may need to be oriented with the major axis of the compressed, substantially elliptical ring at an angle to the cannula axis to facilitate this.
In some embodiments, rather than storing rings proximally as in
In some embodiment variations, rings may be plastically deformed into a compressed form that allows them to be stored within the cannula adjacent to one another, or if their major axes are tilted with respect to the local cannula axis, with some overlap. In other embodiment variations, the rings are elastically deformed into an elliptical shape and retain that shape within the cannula without the aid of the stylet by means of a storage element. For example, as shown in
In some embodiment variations, the cables in the storage element are replaced by rigid segments terminating in balls such as balls 502 and 504, and a flexible element connects ball 504 of one segment with ball 502 of the next most distal segment. In such variations, the overall storage element need not be under tension, since the rigid segments and balls maintain the rings in the proper elliptical shape, and the storage element can bend in 3-D to follow the cannula shape.
In some embodiment variations, features such as notches may be added to the rings to engage the cable or rigid segments. For example, slots may be added to the proximal and distal edges of the rings adjacent to the holes and tabs used for interlocking, and the storage element can engage these. In some embodiment variations features may also be added to rings and/or balls (or other protrusions) to positively secure the rings (e.g., not releasing them until they are made even more elliptical). In some embodiment variations, a single cable may be used, with tab 358 slotted to allow the cable to enter it.
In some embodiments, the storage element may be in the form of a tube or guide within the lumen of the cannula, through which the rings are transported to the distal end of the cannula, and which keeps the rings in a deformed shape during transportation (e.g., preventing them from expanding, if elastically deformed, into an approximately circular shape). In some embodiments, the rings are at least partially plastically deformed into a shape which allows them to be transported through the cannula lumen without applying a substantial force, or any force, to them. Such rings can be fed continuously through the cannula (in some embodiments within a tube or guide), with one ring pushing the ring just distal to it along, for example. Once emerging from the distal end of the cannula, a mechanism can then deform the rings into the required circular shape and swivel and mate them as needed.
In some embodiments, the final circular shape may be maintained by a design that enables the tabs for the major axis of the ring (as-transported) to enter the holes of the ring just proximal to it from the inside rather than from the outside as in
In some embodiments, rings are segmented and hinged (e.g., four equal curved segments with hinges 90° apart). Such a ring can be folded into a flatter configuration for transportation through the cannula by pulling apart diametrically opposite hinges. In this state, rings can be continuously fed, end-to-end, through the cannula, either directly or through an internal tube or guide. Once a ring has reached the distal end of the cannula, it can be unfolded into a circular shape. To prevent it from folding/collapsing, tabs can be designed to enter holes in the ring just proximal to the ring in question such that the ring is held open. In some embodiment variations, the ring may be elastically deformed when mated with the adjacent ring to keep it from folding.
In some embodiments, rings are not themselves transported through the cannula. Rather, a continuous strip of material can be transported through it, having a shape which can be segmented and used to form rings at the distal end. For example, a segment of a strip having one or both edges that are sinusoidal in shape can be joined end-to-end to form a ring that is wedge-shaped/tapered on its proximal and/or distal surface. Segments may be cut off the strip as needed, or if pre-scored, perforated, or otherwise weakened, can be broken off. Joining can be accomplished with interlocking mechanical features, adhesives, welding, fasteners, and many other means known to the art.
Over-expansion of the ring(s) to accommodate spring-back of the material can also be provided.
Since the rings can change in diameter, there is no need to deform them into elliptical shapes and swivel them as in the 17th Embodiment. This can facilitate use of a cannula comprising such rings within solid tissue or within other environments in which there is little or no room beyond the circular confines of the distal cannula end as it evolves. If a balloon is used to expand the rings, it can serve a further purpose in displacing surrounding material (e.g., bluntly dissect tissue) to make room for the ring.
In some embodiments, rings such as those in the 17th Embodiment may be tethered to cables or wires to that they may be retrieved in case they are dropped inside a patient. The cables may be remain attached as long as the cannula is assembled (e.g., with the cables lying alongside the inner wall of the cannula, possibly sandwiched by a liner), or removed after assembly.
Instead of using tabs and holes such as those shown in
In some embodiments rings have built-in curvatures (including rings of zero curvature in which the distal and proximal faces are parallel), much like groups of at least two rings of the kind shown in
In some embodiments, rings may be compressed and remain compressed when desired, or expanded and remain expanded when desired, by designing them to be bistable, with stable configurations of different diameters. For example, a ring may have an expanded shape similar to that of an open umbrella, and a compressed shape similar to that of an umbrella which has turned inside out. In lieu of rings with tabs and holes, rings having mating surfaces which interlock can be used. For example, a set of teeth similar to a crown gear may be provided on the mating surfaces, which may allow many more orientations than tabs and holes, since the teeth can be smaller and more numerous. However, the cannula should then be preloaded in compression to prevent teeth on the two mating rings from separating. This can be accomplished by one or more cables or wires running through the cannula, which can be anchored at every ring if necessary, or the anchor point transferred distally as more rings are added, or by other means, such as magnets.
Sensors may be provided in some embodiments to sense the bending radius of the cannula, detect the magnitude and direction of externally-applied forces, etc.
If the tabs of rings face proximally as in
In some embodiments, the rings may be sections of curved tubing, rather than sections of straight tubing. In such cases, the mating surfaces of the rings can be completely circular.
The strip used in continuously distally assembling/disassembly cannula, or elements of the strip or elements joining one winding of the strip to another, may be intentionally elastic, so as to impart deformability to the cannula when subject to external forces. This may be done for the entire cannula, or just for portions thereof.
A liner introduced into the cannula during or after assembly can be very flexible or stretchable with an outside diameter considerably smaller than the cannula inside diameter, allowing it to be pulled (or even pushed) easily through the cannula, and may be made from a lubricious material such as PTFE thin wall tubing. It may also have a pleated cross section (e.g, formed into a star shape). Once in place, in some embodiments fluid pressure may expand it, and the structure of the cannula (with good radial strength) prevents over-expansion.
In some embodiments, the cannula may be subject to forces which deform it, damage it, or limit the size and shapes it can attain. Such forces may include gravity, buoyancy, wind, viscous drag from fluid motion, friction, reaction forces from manipulated objects, etc. It can therefore be desirable to stabilize the cannula using various means. For example, helium balloons, magnets, or motorized propellers can support at least part of the cannula weight, and mechanisms such as deployable legs or arms—sometimes equipped with claws or other graspers—can support elevated portions of the cannula by making contact with the ground or surrounding features of the environment. For operation in water, the cannula may include ballast tanks, swim bladders, weights, and/or flotation devices (e.g., a double-walled, air-filled liner, a hollow stylet shaft, external floats), for example to achieve near-neutral buoyancy.
Shape memory alloys or polymers incorporated into the cannula may be used in some embodiments to rapidly change its shape once it has been assembled/extended.
In some situations such as certain medical procedures and search and rescue, the desired trajectory of the cannula cannot be predicted before the cannula is actually deployed, thus requiring real-time guidance and path planning. For example, in a search and rescue environment, the cannula may have penetrated through an aperture (e.g., in rubble) and is now in an empty “chamber” having another aperture somewhere else (as recognized by a camera/3-D scanner). To progress, it might be desirable for the cannula to advance though this second aperture. The process for a cannula based on rings can be as follows, and a similar process could be used for continuously distally assembled cannulas:
1. Identify the current position of the most distal ring (i.e., the current distal tip of the cannula. This might be done deterministically, if there is minimum clearance between rings and tight tolerances, or through sensing.
2. Measure the location of the aperture through which the cannula should grow. More specifically, identify a region within the area of the aperture through which the center of the cannula could move without colliding with the sides of the aperture. This needs to take into account the aperture geometry, the cannula diameter, the space needed to manipulate rings, and other factors.
3. Calculate potential trajectories (if more than one) and select the optimal trajectory (i.e., using time to enter the aperture, and select the optimal trajectory (e.g., that requiring the least time).
4. Calculate the sequence of ring orientations needed for the growing cannula to reach and penetrate the region and (simultaneously or subsequently) grow the cannula according to that sequence, thus penetrating through the aperture.
The various embodiments of the invention, set forth explicitly herein or otherwise ascertained from the teachings herein, may be used alone or in any combination.
Medical Applications:
A variety of medical procedures may benefit from the use of devices such as those described herein used as medical instruments to introduce and/or remove fluid, or provide a conduit for the delivery or retrieval of implants or instruments to or from a target region of the body. For example, cancer patients may have brachytherapy seeds implanted in or near tumors, have tissue biopsied or fluid aspirated for analysis, receive chemotherapy agents, or have tumors removed or ablated.
Brachytherapy seeds are normally implanted at multiple sites. Biopsies or fluid aspiration may be performed in multiple locations. Chemotherapy is often delivered intravenously but can be more effective if delivered locally to the site of a tumor, minimizing systemic effects. Patients with atrial fibrillation may be treated by electrical ablation of selected regions of heart tissue. Patients in need of neuromodulation may be implanted with electrodes or other devices.
Continuously distally assembled/disassembled curved cannulas, since their stylets may remain inside as they grow, may be equipped to continuously dissect tissue (e.g., with a balloon, needle, or cutter) affixed to the end of the stylet, for example.
Devices such as those described herein may be made in different sizes, ranging from sub-millimeter in diameter to several centimeters or even larger.
As noted, devices such as those described herein may be used to deliver brachytherapy seeds. In some embodiments, multiple seeds may be loaded into the inner walls of a cannula at a desired axial spacing, and retained by the walls. As the instrument everts, it lengthens and delivers seed after seed into tissue. Such an instrument may extend for a distance, then retract, then extend in a different direction.
Devices such as those described herein may deliver other implants to tissue surfaces or sub-surface; delivery need not be through solid tissue.
Devices such as those described herein may be used to deliver devices which remove or ablate tissue—mechanically, or through laser, thermal, RF, microwave, or cryogenic means, for example.
Devices such as those described herein may deliver drugs such as chemotherapy drugs or pain medication, for example, or embolic particles, microspheres, and other materials. A device might tunnel through tissue and selected regions of organs such as the liver to form a complex 3-D shape that is “space filling” and dispense a drug or ablation agent through holes along the device, in a process akin to drip irrigation. Such a 3-D device might also be used to simultaneously ablate large volumes of unwanted tissue using chemical, radio frequency, ultrasonic, cryogenic, or other means.
Devices such as those described herein may be used for lung biopsy, avoiding delicate structures and minimizing the risk of pneumothorax.
Devices such as those described herein may be used for fine needle aspiration.
Devices such as those described herein may be used to deliver electrodes, or as implanted electrodes for neurostimulation, including deep brain stimulation. For example, a cochlear implant electrode that is atraumatically delivered within the cochlea and which has a large number of discrete electrodes can be distally assembled in a tapered or small diameter cylindrical shape matching that of the cochlea. Such a device may be based on an everting tube, a set of discrete tubes or rings, etc. If comprised of metal (e.g., Pt—Ir, stainless steel, nickel-titanium) rings as in
For some applications, devices such as those disclosed herein and their component parts may be perforated, textured, coated, or otherwise modified to improve the reaction or compatibility with tissue, such as minimizing the risk of thrombus, discouraging bacterial growth, encouraging tissue or bone growth, etc.
For some applications, devices such as those disclosed herein—or attached members such as catheters—may be stabilized, positioned (e.g., centered), and/or anchored inside a patient's body at one or more locations by an inflatable balloon, deployment of fixation devices, etc. For example, a balloon may be used on a device in its proximal region, while the distal region grows into the desired shape.
Devices such as those described herein may be used in minimally-invasive procedures such as sinus surgery and arthroscopic surgery.
Devices such as those described herein may be used within the ventricles of the brain to ablate/remove tumors, biopsy tissue, treat hydrocephalus, or provide injections. In addition, such devices may be used to cool the brain after stroke or other trauma: a cooling liquid compatible with cerebrospinal fluid can be introduced through a flexible catheter deployed within the device, with warm fluid withdrawn through the (e.g., annular) space surrounding the catheter. Fluids can pass through holes in the walls of the devices, or the device can be provided with a liner such that flow is directed through the end of the device and/or other locations. The device can be inserted through a small incision in the skull into the anterior horn of a lateral ventricle, and deployed toward the posterior horn and if desired, into the inferior horn. After deployment, or in some embodiment variations, during deployment, fluid exchange can occur, allowing the brain—and only the brain—to be efficiently cooled from within. Appropriate sealing may be used to prevent cerebrospinal fluid loss during deployment/assembly or retrieval/disassembly of the device and during operation.
Devices such as those described herein may be used in spinal surgery, for example, for microdiscectomy or foraminal stenosis, navigating around obstacles in small spaces. A distally assembled cannula might, for example, be used to provide percutaneous access to a laterally herniated cervical disc through a posterior approach while avoiding sensitive structures; this would avoid the need for the vertebral fusion of a frontal approach. Devices such as those described herein may also be used to “grow” an interbody fusion cage (e.g., with a helical shape) between two vertebral bodies. Since such a cage is distally assembled in-vivo, it can be delivered through a small incision.
Devices such as those described herein may be used in the treatment of atrial fibrillation by ablation (e.g., RF or cryoablation) of the wall of the heart. Such devices may be used to position an ablation electrode or other device against the heart wall during a procedure, or provide a stable platform for a steerable catheter, or may themselves act as an ablation device. For example, a device having a circular or other suitable shape can be deployed within the heart around the pulmonary vein and provided with RF energy or cryogenic cooling, and can be anchored to the heart wall during the procedure, so that it moves with the heart, or moved in synchrony with the heart. Force sensing can also be provided, e.g., by incorporating one or more rings with strain gauges into the device.
Devices such as those described herein may be used in the delivery of enteral feeding tubes through the pyloric sphincter of the stomach, to achieve transpyloric placement.
Devices such as those described herein may be used in urology for stone removal and to correct urinary drainage.
Devices such as those described herein may be used to deliver and affix tissue approximation and closure devices, e.g., in cardiology.
Devices such as those described herein may be used in injections of anesthetics, for example, for epidural spinal anesthesia.
Devices such as those described herein may be used to deliver sutures and similar materials, and form knots in suture.
Devices such as those described herein may be used to treat atrial fibrillation for example as follows: The device may be delivered into/extend into the left atrium of the heart and guide/support a steerable catheter, or itself adopt a shape (e.g., loop-like) in the distal region, with the distal region in contact with the atrium surrounding the ostia of the pulmonary veins (more than a single vein can be surrounded at a time). By applying energy (e.g., RF) through the device, tissue can be ablated such that electrical conduction paths contributing to fibrillation are interrupted.
Devices such as those described herein may be used to place epicardial leads on the heart, e.g., for biventricular pacing.
Devices such as those described herein may be used as annuloplasty rings, for example, to correct mitral valve regurgitation. The device can be inserted percutaneously through a small incision, enter the beating or stopped heart, and grow inside the heart into the complex 3-D shape required to reshape the valve annulus. The device would be anchored to tissue by one method of another. For example, if the device comprises rings such as those of
Devices such as those described herein may be used to perform percutaneous bypass surgery, e.g., of peripheral arteries or coronary arteries. The device can create a proximal anastomosis to, for example, the aorta, e.g., by compressing the aorta wall between two rings such as those of
Devices such as those described herein may be used as stents, stent grafts, shunts (e.g., aneurysm bypass shunts), conduits, and other implants through which bodily fluids pass, and which are intended to provide a patent lumen. For example, stents of adjustable length and curvature can be produced using multiple rings of the kind shown in
Devices such as those described herein may be used within the lumens of blood, lymph and other vessels to help navigate a guidewire or catheter through difficult bifurcations, tortuosity, calcification, or other complex anatomy, for example, in the brain.
Devices such as those described herein may be used in lieu of a guidewire, or in procedures that do not require a guidewire, in interventional radiology and other procedures within body lumens. Devices such as those described herein may be used in navigating tortuous vasculature such as in the brain, and for filling the sacs of neurovascular aneurysms in lieu of detachable coils.
Devices such as those described herein may be used for diagnostic and therapeutic procedures in the gastrointestinal system, such as the stomach, small intestine, and colon. In general, when deployed in narrow and/or curved lumens, devices such as those described herein can minimize potentially traumatic contact with nearly walls of tissue. In general, additional devices used in conjunction with instruments such as those described herein may be may be slid over the instrument. Or, other devices and materials may be passed through a lumen in the instrument. Or, the instrument may be used as a platform to support another instrument at its distal end which is desired for a procedure (e.g., a biopsy or ablation device). Distally extendable instruments may be used as type of steerable, fully or partially self-supporting, track along or inside of which devices and material can be transported.
Devices such as those described herein may be used as neural electrodes or other temporary or permanently-implanted structure which can be thin yet be inserted without buckling by growing from its distal end, yet be flexible so as to maximize compatibility with surrounding tissue.
Non-Medical Applications:
Devices such as those described herein may be used as robotic arms and manipulators.
Devices such as those described herein may be used for oil and gas exploration and production, for example, in lieu of standard casings normally placed within a well, or for drilling a well at any desired depth and angle (e.g., for horizontal drilling).
Devices such as those described herein may be used in civil engineering and architecture to create useful structures.
Devices such as those described herein may be used to navigate through irregular debris in search and rescue operations, (e.g., in collapsed mines, and collapsed buildings). A device (e.g., with an outside diameter in the range of 10-40 mm) can navigate autonomously or under operator control to grow in a complex 3-D shape through nooks and crannies (e.g., using a camera, laser-based instruments) to reach trapped disaster victims before heavy machinery can remove rubble to free them. It can deploy sensors along the way or upon reaching its destination, allowing its position and that of the victims to be identified. Through the lumen, air, water, food (e.g., in liquid form), and medical supplies can be furnished to the victims, and cameras and two-way communication devices can be delivered, allowing continuous communications. To facilitate its ability to extend through various materials at the disaster site, the device can be provided with a powerful vacuum system and if needed, an airproof liner, so that dust, dirt, and smaller rocks and debris can be extracted through it. When no alternative presents itself, a drill can be deployed through the device, driven hydraulically or using a rotating flexible shaft, allowing penetration of hard materials. In the case of a continuously distally assembled/disassembled curved cannula, the stylet can remain inside as the cannula grows, with its distal end near the cannula distal end, allowing the drill to function continuously. The device can also serve to deploy reinforcing cables that stabilize heavy debris at risk of shifting and collapsing on the victims, e.g., during rescue operations.
After an earthquake or other disaster leading to the collapse of a building, for example, rapidly locating and making contact with survivors is of paramount importance. This can be a very challenging task for first responders and for conventional robots since the environment is characterized by irregular debris forming multiple random, randomly-interconnected chambers, granular media, structures which may shift or collapse under additional weight, and other obstacles to mobility. The path from rescuer to victim, if one exists before lifting away the rubble, is often tortuous and accessible only through small chinks. A man-portable or vehicle-mounted cannula system could feature a cannula of, for example, 10-30 mm diameter that could be snaked through the chinks (even if filled with soil or other debris, which can be blown away), seeking out a passage to survivors whose locations may be pre-determined using canines, listening devices, radar, or by using the cannula system itself in an exploratory mode. While advancing, the cannula can avoid rubbing against and disturbing structures around it. Once it has reached its destination, two-way communications can be immediately established via microphone, loudspeaker, and camera. Perhaps more importantly, the cannula can continuously transport needed quantities of air, oxygen, water, and even food and medical supplies to victims through the lumen, maximizing the chances of survival before they can be reached. If the cannula is steered into what turns out to be a dead end, it can easily retract, in effect time-reversing the exact path it had taken, and then extend again in a new direction.
Devices such as those described herein (e.g., with a larger diameter than would be used for a medical application) may be used for disaster-related cleanup of hazardous environments, e.g., contaminated nuclear reactor and weapons sites, where they can be deployed through available openings, extend through stairwells without having to climb stairs or fly like a mobile robot (which consumes power), all the while being immune to hazards such as radiation (since there are no electronics required to grow and maneuver), and slippery or submerged surfaces. Through the lumen cleaning agents can be delivered, and debris can be vacuumed up, among other useful operations such as performing surveillance of the facility.
The decontamination and decommissioning of dangerous facilities such as nuclear power plants that have suffered accidents, such as the Fukushima Daiichi plant in Japan, of retired power plants worldwide, or of obsolete weapons facilities in the U.S., is a process needing years or decades to complete. It is also an extremely costly (e.g., $17B for Fukushima) and difficult process due to radioactive contamination, high temperatures and pressures, explosive materials, wet or submerged areas, rubble, and other factors which make the environment very inhospitable for human workers. Robots may therefore help complete the required activities including surveying and inspection, non-destructive evaluation, repair, and removal of contaminated debris and fluids. While wheeled, tracked, or legged robots can accomplish some tasks, their mobility is limited by the existence of surfaces which are difficult to traverse due to obstacles, liquids, granular materials, and gaps; by the three-dimensional nature of many structures (e.g., multiple floors, stairs, shafts); and by the need for power and communications. If tethered for power and communications, the tether limits maneuverability and can become tangled or snagged, yet untethered robots must rely on short-lived batteries. Flying drones can avoid surface hazards and move in any open direction; however, they too are limited by tethers or batteries, and can be too large to enter pipes, ducts, or narrow openings. Moreover, they must be well controlled to avoid collisions in cramped spaces. Finally, neither surface nor flying robots have much capability for material transport: the ability to deliver cleaning agents or remove contaminants.
A distally assembled cannula could be scaled to 10s of cm in diameter and 10s of meters long, as long as its weight can be supported by grappling surrounding objects, by deployable “stilts”, or if immersed in liquid, by floats. Such a device could be extremely versatile and overcome some of the limitations of conventional robots. The cannula's console (
A benefit of distally assembled cannula is that its operation can be highly tolerant of hazardous environments, such as those involving high temperatures and pressures, deep accumulations of liquids, and intense radiation. The cannula itself, made only from metal, is intrinsically radiation tolerant, though it may suffer embrittlement from intense radiation over time. The stylet can also be metal and designed so that all actuators are located at a distance within the console, which can be in a non-irradiated environment. Lighting and non-destructive testing (NDT) sensors (e.g., acoustic, optical, thermal) required at the distal end of the cannula can be radiation hardened. Metallic components can be coated if needed to suppress potential spark hazards near explosive materials. The cannula can operate for extended missions without maintenance and with constant communications from its distal to its proximal end; its shape should be largely deterministic, minimizing reliance on sensors and GPS to pinpoint the location of its distal end.
Devices such as those described herein may be used underwater to help clean and repair the hulls of large ships.
Devices such as those described herein may be used to travel through complex 3-D spaces such as piping networks.
Devices such as those described herein may be used to navigate around or through an object for purposes of inspection, delivery or retrieval of materials, etc.
Devices such as those described herein may be used to explore tunnels, trenches, crevices, fissures, and otherwise difficult-to-navigate areas. Such areas may be underwater or extraterrestrial, e.g., exploring deep ocean trenches or crevices on Mars. Devices such as those described herein may be used as a form of kinetic sculpture.
Devices such as those described herein may be used as toys, for example, in a construction set allowing complex 3-D tunnels to be quickly assembled (e.g., through which marbles may be released). In such uses, circular rings similar to those of
Devices such as those described herein may be used as molds or mandrels, in which a solidifiable material (e.g., concrete, thermoplastic, thermoset, UV-curable material, fiber-reinforced composite) is placed within or on the exterior surface of the device, and then solidified, maintaining the shape even if the device is thereafter removed (e.g., by disassembly). In some embodiments, a liner or a surrounding sleeve can be placed in or over the device before the solidifiable material is applied to provide a minimally-porous surface that retains the material. Material can be added gradually as the device is assembled, or added only once the entire device has been assembled.
Devices such as those described herein may be used in vacuum environments and under conditions of neutral bouyancy or low/zero gravity, for example, for inspection, manipulation, retrieval, transport of solid, liquid, or gas material. For example, such devices may allow inspection behind large objects that are difficult to move, within deep cavities within a structure, or inside deep and crevasses with complex shapes.
The International Space Station, among other current and future space platforms, has inspection requirements that are not easily met by existing robotic devices. For example, the ISS contains multiple, large racks of equipment. If there is a suspected leak or other potential issue behind such equipment, it normally would need to be removed in order to obtain access: a time-consuming process. A minimally invasive approach would be much preferred. If equipped with a miniature camera (e.g., on the stylet) and sufficiently small in diameter, a distally assembled cannula could be commanded to quickly weave its way through small openings and provide video of the environment behind the equipment. Being self-supporting especially in microgravity, the cannula could easily follow an arbitrary 3-D path, including for example growing out of a hole, extending across an open space, and entering another hole unaligned with the first hole.
The cannula console can be permanently mounted to a post or wall; with a 3 meter reach, for example, it would have access to a volume as large as 100 cubic meters. Multiple systems equipped with cameras and microphones could be so mounted, and be teleoperated by ground or mission crews to allow continuous monitoring of the ISS. Being compact with the cannula stowed, the cannula system could also be carried and delivered to the site of interest by a crew member, be attached to or carried by a larger robot, or even integrated into a free flying robot. Unlike free flying robots, cannulas can pass through very small openings, never needs to perch, and its actuators consume no power when the cannula is static. Since the cannula is tethered to the console, power can easily be supplied when extending or retracting or for operating a distal camera, etc.
In addition to inspection, other intravehicular space applications for cannulas include environmental surveys (e.g., sound level, air quality) with the appropriate sensor package, and inventory management (e.g., if equipped with an RFID reader). Extravehicular opportunities for cannulas include surveying internal damage to structures penetrated by micrometeoroids and orbital debris. Cannulas can be slender enough to fit under thermal blankets, leaving them intact while exploring what is hidden to the outside. It can be equipped with tactile and force sensors as required by the mission. Cannulas could assist in maintaining and repairing systems on board the ISS. It might have a role as a versatile, deployable structure able to transport tools and materials in support of space needs such as the Robotic Refueling Mission, docking assistance, and on-orbit assembly. Finally, planetary landers could use cannulas as a means for exploring deep and tortuous crevasses on the surface.
Cannulas can be built to contain no electronics or actuators and thus be tolerant to radiation and to temperature extremes. While the stylet may include actuators and sensors, it can be withdrawn when not needed, minimizing its exposure. The cannula or stylet can be equipped with grippers and other tools, and being hollow, many devices can be passed through it such as a borescope with steerable tip. While the cannula by itself is not fluid-tight, it can be made so by delivering a flexible liner, allowing transport of liquids and gasses.
Devices such as those described herein may be used for underwater exploration (e.g., of trenches), surveillance (e.g., naval intelligence gathering in environments obscured by underwater vegetation such as reeds in swampy areas), economically laying conduit for underground power and fiber optic cables, and even to plant seeds underground (e.g., as the cannula retracts, seeds could be pushed out).
Devices such as those described herein may be used by bomb squads to inspect, safely de-activate, or remotely detonate a bomb; or in urban police, military, and anti-terror actions in which surveillance, delivery of a non-lethal weapon, etc. within a building or other structure is needed, and access is limited to circuitous paths and/or small openings.
Devices such as those described herein may be used to supply buildings and vehicles from another building or vehicle, for example, for in-air refueling of one aircraft by another, or for recharging or refueling of an unmanned aerial vehicle from the ground.
Devices such as those described herein may be used to transport objects using fluid forces, such as using gas or liquid pressure, or the force of rapidly-expanding gas after an explosion (i.e., devices such as those described herein may be used as steerable gun barrels).
Devices such as those described herein may be used in firefighting to carry water (or other flowable extinguishing agent), delivering the water within a building on any required floor through a small opening (e.g., a hole in a window produced by the distal end of the device through cutting or breaking). Fumes and smoke may also be extracted by devices such as those described herein.
Devices such as those described herein may be used to support light fixtures, cameras, and the like for photography and cinematography.
It will be understood that particular embodiments described herein are shown by way of illustration and not as limitations of the invention. The principal features of this invention can be employed in various embodiments without departing from the scope of the invention. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, numerous equivalents to the specific procedures described herein. Such equivalents are considered to be within the scope of this invention and are covered by the claims.
All publications and patent applications mentioned in the specification are indicative of the level of skill of those skilled in the art to which this invention pertains. All publications and patent applications are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.
The use of the word “a” or “an” when used in conjunction with the term “comprising” in the claims and/or the specification may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.” The use of the term “or” in the claims is used to mean “and/or” unless explicitly indicated to refer to alternatives only or the alternatives are mutually exclusive, although the disclosure supports a definition that refers to only alternatives and “and/or.” Throughout this application, the term “about” is used to indicate that a value includes the inherent variation of error for the device, the method being employed to determine the value, or the variation that exists among the study subjects.
As used in this specification and claim(s), the words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.
The term “or combinations thereof” as used herein refers to all permutations and combinations of the listed items preceding the term. For example, “A, B, C, or combinations thereof” is intended to include at least one of: A, B, C, AB, AC, BC, or ABC, and if order is important in a particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB. Continuing with this example, expressly included are combinations that contain repeats of one or more item or term, such as BB, AAA, AB, BBC, AAABCCCC, CBBAAA, CABABB, and so forth. The skilled artisan will understand that typically there is no limit on the number of items or terms in any combination, unless otherwise apparent from the context. In certain embodiments, the present invention may also include methods and compositions in which the transition phrase “consisting essentially of” or “consisting of” may also be used.
As used herein, words of approximation such as, without limitation, “about”, “substantial” or “substantially” refers to a condition that when so modified is understood to not necessarily be absolute or perfect but would be considered close enough to those of ordinary skill in the art to warrant designating the condition as being present. The extent to which the description may vary will depend on how great a change can be instituted and still have one of ordinary skilled in the art recognize the modified feature as still having the required characteristics and capabilities of the unmodified feature. In general, but subject to the preceding discussion, a numerical value herein that is modified by a word of approximation such as “about” may vary from the stated value by at least ±1, 2, 3, 4, 5, 6, 7, 10, 12 or 15%.
All of the compositions and/or methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the compositions and methods of this invention have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the compositions and/or methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit and scope of the invention. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined by the appended claims.
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Claims
1. An elongatable, steerable apparatus capable of growing from a proximal end to a distal end through a process of assembly wherein one or more segments are added to the distal end of the apparatus, the apparatus comprising:
- a first segment having a lumen therethrough, the first segment having a proximal end and a distal end; and
- a second segment having a lumen, a proximal end, and a distal end, wherein the second segment is deliverable via a segment transporter to the distal end of the first segment, wherein the segment transporter attaches the second segment to the first segment, wherein the second segment is capable of changing the growth direction of the distal end of the apparatus and of one or more subsequent segments.
2. The apparatus of claim 1, apparatus capable of lengthening from a proximal end to a distal end through a process of assembly wherein one or more segments are added to the distal end of the apparatus, and wherein the apparatus grows along a desired curved path in space based on a tapered shape of each additional segment; or wherein the lengthening of the apparatus along the desired curved path in space is a result of stacking the one or more segments and the one or more segments comprise one or more straight, tapered, or offset segments.
3. The apparatus of claim 1, wherein the at least first, second, or subsequent segments, may attach or interlock to each other by friction, abrasive contact surfaces, self-adhesive strips, hook and loop fasteners, hooks and eyes, ties, tabs, holes, buckles, belts, pins, elastic bands, rubber bands, snaps, clasps, magnets, zippers, DUAL LOCK™, or VELCRO™ tape fasteners.
4. The apparatus of claim 1, wherein the lengthening of the apparatus along the desired curved path in space is a result of transporting the segments through a lumen in the apparatus.
5. The apparatus of claim 1, wherein the apparatus is a cannula capable of growing from a proximal end to a distal end and capable of a non-linear configuration comprising:
- one or more segments having a lumen and substantially cylindrical in their uncompressed state and having a distal face and a proximal face that are non-parallel, wherein the one or more segments can be transformed into a non-cylindrical, substantially elliptical shape;
- a segment transporter that transports one or more additional segments in their non-cylindrical, substantially elliptical shape through the substantially cylindrical segments; and
- a coupling mechanism that engages the one or more segments to an adjacent segment, whereby at least one of the segments is transported through the lumen of the one or more substantially cylindrical segments to reach a distal location, and transformed to couple to the most distal of the segments, thereby growing the cannula.
6. The apparatus of claim 5, wherein the segment transporter is capable of at least one of swiveling, rotating, coupling or transporting a segment.
7. The apparatus of claim 5, wherein a swiveling axis of the segment is substantially parallel to a minor axis of the non-cylindrical, substantially elliptical shape of the segment.
8. The apparatus of claim 5, wherein a distal face of a first segment is substantially perpendicular to a substantially cylindrical axis of the first segment, and a proximal face of a first segment is substantially non-perpendicular to the substantially cylindrical axis of the first segment;
- a distal face of a second segment is substantially non-perpendicular to a substantially cylindrical axis of the second segment, and a proximal face of a second segment is substantially perpendicular to the substantially cylindrical axis of the second segment; and
- wherein the swiveling axis is substantially perpendicular to a plane formed by the substantially cylindrical axis and a normal to the substantially non-perpendicular face of the segment.
9. The apparatus of claim 5, wherein the segments comprise one or more holes along a distal edge of the segment and one or more tabs that extend from a proximal edge of the segments, wherein the one or more tabs fit within the one or more holes to couple two adjacent segments; each segment comprises two or more tabs that are equally spaced around the circumference of the segment; or each segment comprises two holes that are substantially parallel to the swiveling axis.
10. The apparatus of claim 9, wherein the tabs are substantially aligned with the major and minor axes of the substantially elliptical shape assumed by the rings when transformed; or
- wherein at least one first tab in the distal segment of a pair of adjacent segments enters a hole in the proximal segment of a pair of adjacent segments from the inside of the proximal segment, and at least one second tab on the non-opposite side of the distal segment enters a hole from the outside of the proximal segment to couple the segments.
11. The apparatus of claim 1, wherein the apparatus is an elongatable, steerable cannula capable of growing from a proximal end to a distal end through a process of assembly wherein one or more segments are added to the distal end of the cannula;
- wherein the first segment is a first flexible segment substantially cylindrical in axial cross section when uncompressed and substantially elliptical when compressed, having a first lumen therethrough, the first segment having a first proximal face substantially perpendicular to a first substantially cylindrical axis and provided with one or more first male coupling elements, and a first distal face substantially non-perpendicular to the substantially cylindrical axis and provided with a first plurality of female coupling elements;
- wherein the second segment is a second flexible segment substantially cylindrical in axial cross section when uncompressed and substantially elliptical when compressed, having a second lumen therethrough, the second segment having a second proximal face substantially non-perpendicular to a second substantially cylindrical axis and provided with one or more second male coupling elements, and a second distal face substantially perpendicular to the second substantially cylindrical axis and provided with a second plurality of female coupling elements;
- a flexible shaft provided with grippers able to grip said first and said second segment to compress and allow to decompress said segments, swivel or allow to swivel said segments about axes substantially parallel to the minor axes of said first and second segments when compressed and substantially elliptical, and transport said segments through said lumen;
- wherein said flexible shaft transports said second segment through said lumen of said first segment, then rotates said second segment as required around an axis substantially coincident with the longitudinal axis of the flexible shaft, brings the proximal face of said second segment in contact with the distal face of said first segment, allows said second segment to decompress while allowing two of said second male coupling elements to enter two of said first plurality of female coupling elements from the inside and two of said second male coupling elements to enter two of said first plurality of female coupling elements from the outside; and
- wherein said flexible shaft transports said first segment through said lumen of said second segment, rotates said first segment as required around an axis substantially coincident with the longitudinal axis of the flexible shaft, brings the proximal face of said first segment in contact with the distal face of said second segment, then allows said first segment to decompress while allowing two of said first male coupling elements to enter two of said second plurality of female coupling elements from the inside and two of said first male coupling elements to enter two of said second plurality of female coupling elements from the outside.
12. The apparatus of claim 11, wherein the segments comprise a superelastic nickel-titanium material.
13. The apparatus of claim 11, wherein the first and second male coupling elements comprise interlocking male and female elements such that the adjacent segments are mechanically interlocked when the segments are decompressed;
- wherein a plurality of first and second segments are arranged in an alternating pattern within the cannula;
- wherein the angle between the first proximal face and second distal face is varied by varying the relative orientation of the first and second segments when coupled together;
- wherein the relative orientation is varied as required by rotating the second segment substantially about an axis substantially coincident with the longitudinal axis of the flexible shaft prior to coupling the second segment to the first segment;
- wherein the minor axis of the compressed, substantially elliptical second segment is substantially perpendicular to the plane defined by the substantially non-perpendicular second proximal face and the second substantially cylindrical axis, and wherein the minor axis of the compressed, substantially elliptical first segment is substantially perpendicular to the plane defined by the substantially non-perpendicular first distal face and the first substantially cylindrical axis, and wherein the second segment is swiveled about its minor axis and its major axis is substantially parallel to the first cylinder axis during transport by the flexible shaft, and wherein the first segment is swiveled about its minor axis and its major axis is substantially parallel to the second cylinder axis during transport by the flexible shaft;
- wherein the second segment is rotated as required relative to the first segment prior to allowing the second segment to decompress, and wherein the first segment is rotated relative to the second segment prior to allowing the first segment to decompress; or
- wherein the grippers are supported by a fork that is compressed by a sliding tube, or the grippers are supported by a flexible ring that is expanded by applying tension to a wire attached to its distal end.
14. The apparatus of claim 1, wherein the apparatus is an elongatable, steerable cannula capable of growing from a proximal end to a distal end through a process of assembly wherein one or more segments are added to the distal end of the cannula, wherein:
- the first segment is a first expandable segment substantially cylindrical in axial cross section having a first lumen therethrough, the first segment having a first proximal face substantially perpendicular to a first substantially cylindrical axis and provided with a first plurality of male coupling elements, and a first distal face substantially non-perpendicular to the substantially cylindrical axis and provided with a first plurality of female coupling elements;
- the second segment is a second expandable segment substantially cylindrical in axial cross section having a second lumen therethrough, the second segment having a second proximal face substantially non-perpendicular to a second substantially cylindrical axis and provided with a second plurality of male coupling elements, and a second distal face substantially perpendicular to the second substantially cylindrical axis and provided with a second plurality of female coupling elements;
- a flexible shaft provided with an expanding member to expand and orient said first and said second segments, and transport said segments through said lumens;
- wherein said flexible shaft transports said second segment through said lumen of said first segment, rotates said second segment as required around an axis substantially coincident with the longitudinal axis of the flexible shaft, brings the proximal face of said second segment in contact with the distal face of said first segment, then expands said second segment and allows second plurality of male coupling elements to enter said first plurality of female coupling elements from the inside; and
- wherein said flexible shaft transports said first segment through said lumen of said second segment, rotates said first segment as required around an axis substantially coincident with the longitudinal axis of the flexible shaft, brings the proximal face of said first segment in contact with the distal face of said second segment, then expands said first segment and allows first plurality of male coupling elements to enter said second plurality of female coupling elements from the inside.
15. The apparatus of claim 1, wherein the apparatus is an elongatable, steerable cannula capable of growing from a proximal end to a distal end through a process of everting, the cannula further comprising:
- an expandable tube having a relatively flexible inner wall of relatively small diameter and an relatively inflexible outer wall of relatively large diameter;
- a device for everting the tube to grow the cannula from its distal end by progressively transforming the inner wall into an outer wall;
- a steering mechanism for controlling the direction in which the cannula grows by varying the rate at which the inner wall is transformed into outer wall according to location around the circumference of the inner wall, wherein the expandable tube is optionally a braided superelastic nickel-titanium wire or an elastomer.
16. A method of making an elongatable, steerable cannula capable of growing from a proximal end to a distal end through a process of assembly wherein one or more segments are added to the distal end of the cannula, the method comprising:
- obtaining a first flexible segment substantially cylindrical in axial cross section when uncompressed and substantially elliptical when compressed, having a first lumen therethrough, the first segment having a first proximal face substantially perpendicular to a first substantially cylindrical axis and provided with one or more first male coupling elements, and a first distal face substantially non-perpendicular to the substantially cylindrical axis and provided with a first plurality of female coupling elements;
- positioning a second flexible segment substantially cylindrical in axial cross section when uncompressed and substantially elliptical when compressed, having a second lumen therethrough, the second segment having a second proximal face substantially non-perpendicular to a second substantially cylindrical axis and provided with one or more second male coupling elements, and a second distal face substantially perpendicular to the second substantially cylindrical axis and provided with a second plurality of female coupling elements;
- inserting a flexible shaft provided with grippers able to grip said first and said second segment to compress and allow to decompress said segments, swivel or allow to swivel said segments about axes substantially parallel to the minor axes of said first and second segments, and transport said segments through said lumen;
- wherein said flexible shaft transports said second segment through said lumen of said first segment, then allows said second segment to decompress while allowing two of said second male coupling elements to enter two of said first plurality of female coupling elements from the inside and two of said second male coupling elements to enter two of said first plurality of female coupling elements from the outside; and
- wherein said flexible shaft transports said first segment through said lumen of said second segment, then allows said first segment to decompress while allowing two of said first male coupling elements to enter two of said second plurality of female coupling elements from the inside and two of said first male coupling elements to enter two of said second plurality of female coupling elements from the outside.
17. The method of claim 16, wherein the steps are further defined as:
- obtaining a first expandable segment substantially cylindrical in axial cross section having a first lumen therethrough, the first segment having a first proximal face substantially perpendicular to a first substantially cylindrical axis and provided with a first plurality of male coupling elements, and a first distal face substantially non-perpendicular to the substantially cylindrical axis and provided with a first plurality of female coupling elements;
- positioning a second expandable segment substantially cylindrical in axial cross section having a second lumen therethrough, the second segment having a second proximal face substantially non-perpendicular to a second substantially cylindrical axis and provided with a second plurality of male coupling elements, and a second distal face substantially perpendicular to the second substantially cylindrical axis and provided with a second plurality of female coupling elements; and
- inserting a flexible shaft provided with an expanding member to expand and orient said first and said second segments, and transport said segments through said lumens;
- wherein said flexible shaft transports said second segment through said lumen of said first segment, rotates said second segment as required around an axis substantially coincident with the longitudinal axis of the flexible shaft, brings the proximal face of said second segment in contact with the distal face of said first segment, then expands said second segment and allows said second plurality of male coupling elements to enter said first plurality of female coupling elements from the inside; and
- wherein said flexible shaft transports said first segment through said lumen of said second segment, rotates said first segment as required around an axis substantially coincident with the longitudinal axis of the flexible shaft, brings the proximal face of said first segment in contact with the distal face of said second segment, then expands said first segment and allows said first plurality of male coupling elements to enter said second plurality of female coupling elements from the inside.
18. The method of claim 16, wherein making an elongatable, steerable cannula capable of growing from a proximal end to a distal end through a process of everting, the cannula comprises:
- obtaining a flexible, expandable tube capable of being everted,
- positioning a device for everting the tube to grow the cannula from its distal end by progressively transforming the inner wall into an outer wall, rigidifying the outer wall as it is formed; and
- inserting a steering mechanism for controlling the direction in which the rigid outer wall grows by varying the rate, according to location around the circumference of the inner wall, at which the inner wall is transformed into the outer wall.
19. An adjustable structure comprising one or more flexible strips, the one or more flexible strips having a length and a width, comprising:
- one or more fastening elements that join a first edge of the flexible strip in a first region to a second edge of the flexible strip in a second region; and
- one or more elements positioned between the first and second edge that vary the width of the flexible strip along its length, wherein the strip can be formed into a tube with a curved 3-D shape.
20. The adjustable structure of claim 19, further comprising at least two flexible bands separated by a gap, wherein a gap between the flexible strips can be adjusted to vary the width of the adjustable structure.
21. The adjustable structure of claim 20, wherein the gap can be adjusted by a screw, or the gap can be adjusted by at least one of: interleaved fingers, a cam, a screw and a nut plate, or wedges; or
- wherein the width of the strip can be varied using a expandable region, or the width of the strip can be varied using a corrugated region.
22. A stylet for assembling and disassembling a continuously assembled distally curved cannula comprising:
- a stylet having a head and a guide having a proximal and a distal end, wherein a strip of flexible material enters the proximal end of the guide and exits at the distal end, wherein the strip that exits in the distal region of guide forms the cannula; and
- a joiner that joins a first region of the strip to a second region of the strip to form the cannula, wherein a width of the strip can vary along its length, wherein the joiner transforms the strip into the cannula, and optionally, wherein the stylet comprises a guide through or along which the strip traverses from the proximal to the distal end during assembly of the cannula, or traverses from the distal to the proximal end during disassembly.
23. A method of forming an elongatable tube having a lumen, a proximal portion, and an elongating distal portion comprising:
- obtaining a flexible strip having at least a first and a second edge of material having a length and a width;
- winding the flexible strip into a tubular shape;
- joining the at least first edge to the second edge of the flexible strip;
- transporting an unwound section of the strip through the lumen from the proximal portion to the elongating distal portion;
- wherein a distal section of the strip forms the proximal portion of the tube and wherein a proximal section of the strip forms a distal portion of the tube.
24. The method of claim 23, wherein a stylet within the lumen of the elongatable tube is actuated to perform at least one of winding, joining, or transporting the strip;
- wherein the width of the flexible strip has a third edge and wherein the joining comprises joining the first edge of a first section of the flexible strip to at least one of the second or third edge of a second section of the flexible strip; or the width of the flexible strip is locally varied along the length of the flexible strip to determine the local tube radius and plane of curvature;
- wherein the step of joining is further defined as comprising the step of overlapping the first edge of a first section of the flexible strip with the second edge of a second section of the flexible strip by a distance controlled by the stylet; or
- wherein the distance is locally varied along the length of the flexible strip to determine the local tube radius and plane of curvature of the elongatable tube.
25. A mechanical system comprising:
- a flexible strip of material capable of being wound and joined to itself to form a flexible elongatable tube having a lumen;
- an stylet able to move along the along a longitudinal axis of the flexible elongatable tube;
- wherein the stylet is actuatable to perform at least one of winding or joining the flexible strip, wherein the stylet adjusts the width or overlap of the flexible strip to produce a change in the elongation direction of the flexible elongatable tube;
- wherein the flexible elongatable tube further comprises:
- two or more adjacent bands each having a length, wherein each of the bands are approximately parallel to the length of the strip, each band and having an interior and an exterior edge, wherein each of the bands is separated by a spacer;
- a stylet that adjusts the position, shape, or size of the spacer to locally vary a gap separating the bands;
- wherein the bands can be formed into a curved tube by changing the size of the gap between the bands such that a local radius and plane of curvature of the flexible elongatable tube is determined by the gap.
Type: Application
Filed: Apr 15, 2021
Publication Date: Sep 23, 2021
Inventors: Adam Cohen (Dallas, TX), Edmond Richer (Richardson, TX)
Application Number: 17/231,939
