Fluid Sample Transport Devices and Methods
Arrangements are provided including a fluid transport tube, or a needle, having a first end and a second end opposite the first end, and a lumen having an inner diameter. At least one fluid transport enhancing projection is disposed in the lumen and extends from the second end toward the first end. A discreet, wearable blood glucose monitor including such arrangements is also described.
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The presented invention is directed to devices, arrangements and associated methods for effectively transporting fluids, for example, samples of body fluids.
BACKGROUND OF THE INVENTIONIn the following discussion certain articles and methods will be described for background and introductory purposes. Nothing contained herein is to be construed as an “admission” of prior art. Applicant expressly reserves the right to demonstrate, where appropriate, that the articles and methods referenced herein do not constitute prior art under the applicable statutory provisions.
According to the American Diabetes Association, diabetes is the fifth-deadliest disease in the United States and kills more than 213,000 people a year, the total economic cost of diabetes in 2002 was estimated at over $132 billion dollars, and the risk of developing type I juvenile diabetes is higher than virtually all other chronic childhood diseases.
In certain medical treatment and diagnostic procedures, it is necessary to transport body fluid from the patient to a remote location. For example, one such procedure is the testing of a sample of body fluid, such as blood for the glucose concentration level contained therein. Such diagnostic procedures may be conducted clinically or by the patient utilizing a self-testing device or arrangement. There are numerous devices and systems designed to be utilized by the patient for obtaining a sample of blood, and testing the sample to determine the glucose content at a particular point in time. One such system generally includes at least three separate devices. The first device is utilized to draw a sample of blood from the patient by performing a lancing or similar skin piercing operation. Lancets are solid members which do not include a pathway for transporting the sample of blood. Since the lancets do not offer the ability to transport the sample, a separate member or component must be provided for this purpose. Typically, such systems include a separate test strip member which is manually brought into contact with the sample of blood produced by the lancing operation. The sample is then introduced onto the test strip, which includes a mechanism, such as a chemical reagent, for reacting with the blood sample and producing a readable signal. To this end, a separate meter or other reading device is also included in the system. The test strip is typically introduced into the meter, which then interacts with the test strip to produce the quantification of the glucose content contained in the sample of blood.
Such systems suffer from certain drawbacks. The manual operations of lancing, bringing the test strip into contact with the sample of blood thus produced, and the separate step of inserting the test strip into the meter may be difficult to perform for some patients. For instance, diabetics often times suffer from visual impairment as a result of their condition. Thus, it may be difficult for them to locate the sample of blood on the surface of the skin and bring the test strip into communication therewith. Similarly, it may be difficult to properly insert the test strip into the meter. In addition, there is a trend toward minimizing the size of the lancet used to perform the lancing operation in an effort to minimize the pain and required blood volume for the meter associated with this self testing procedure, thereby promoting more frequent testing. The use of a smaller gauge lancet also results in a smaller volume of body fluid, or blood, produced by the lancing operation. Such smaller samples of blood may be even more difficult to locate by the patient, and also may be more challenging to transport effectively.
Other systems for self-testing on the market attempt to integrate one or more above-described lancing, transporting and quantification operations. One such system requires the user to load a lancet and a test strip into a device, which includes a meter. Once loaded the device is held against the skin and the test initiated by the user, which includes a lancing operation and subsequent transport of a sample of body fluid into the test strip. This arrangement still requires the manual step of loading a separate lancet and test strip correctly into the device, and orienting the device correctly at the surface of the skin in order to perform each test. This device also uses the lancet, which in and of itself does not provide a mechanism to transport the sample of blood. Thus, it is necessary to provide a separate mechanism, which enables transportation of the blood from the surface of the skin to the test strip. In this particular device, the transport function is performed by automatically moving the test strip, which includes capillary channels, into communication with the sample of blood at the surface of the skin. If the test strip is not loaded correctly, or the mechanisms for moving the test strip into position do not function correctly, the device will not function properly. Moreover, the user must purchase, store, handle and load the separate lancet and test strip components for each test. Thus, the successful performance for each test is again at least partially dependent upon the patient correctly associating the lancet and the test strip with the device for each and every test performed.
Yet another conventional self-testing system includes multiple disposable parts for lancing and analyte quantification. In this particular device, a test strip is provided which has an integrated blood transport member in the form of a capillary tube extending from a major planar surface thereof which must be brought into communication with the droplet of blood formed on the surface of the skin resulting from a lancing operation. In order to facilitate the transport function, the test strip is provided with a separate spreading layer sandwiched between the end of the capillary tube and a reagent membrane disposed on an opposing side thereof. The spreading layer facilitates transfer of the blood from the tube to the reagent layer. This system is designed such that a sample volume that completely fills the tube is required in order to obtain an accurate test result. Thus, approximately two micro liters of blood is typically required to be drawn from the patient such that the tube can be completely filled and transferred for further analysis. This requires creation of a wound in the skin large enough to express the necessary volume of blood, thus limiting lancet size reduction efforts, and perhaps increasing the manual milking of the wound to bring an adequate volume of blood to the surface of the skin of the patient. Also, the process of completely filling the tube is time consuming. This design also requires the blood to flow through the spreading layer prior to reaching the reagent layer. This two-layer structure is less than optimal from an assembly standpoint in that it requires the assembly of multiple distinct layers. Since the volume of the capillary tube must be first transferred through the spreading layer, this may also have a tendency to slow down the testing procedure and reduce the volume of sample available for analysis.
Thus, conventional body fluid transport systems for medical treatment and/or diagnostic procedures suffer certain drawbacks. Such drawbacks include transport operations that are reliant upon the dexterity and ability of the patient to accurately perform various manual procedures. The conventional devices and arrangements also are not fully integrated and require significant intervention on the part of the user in order to perform an accurate test.
SUMMARY OF THE INVENTIONIt is, therefore, an object of this invention to provide devices, arrangements and methods for improved transport of a body fluid, such as blood.
According to the current principles of the present invention, one or more of the following advantages may be derived from such devices, arrangements and methods. Consistent with the principles of the present invention, a body fluid can be transported without the necessity of performing various operations or procedures by the patient or user of the device. Thus, for example, it is unnecessary for the patient or user of the device to manually bring a fluid member in communication with a droplet of blood on the surface of skin.
According to the present invention, it is also unnecessary to provide a body fluid sample having a volume at least large enough to fill a capillary tube or other fluid transport member, thus reducing the time necessary to perform a test as well as providing an opportunity to create a smaller wound in the surface of the skin, thereby minimizing pain associated with a lancing or other wound creating procedure.
According to the principles of the current invention improved fluid transport can be provided by associating fluid transport with a fully integrated device. A fully integrated device formed according to the principles of the present invention provides for a potential lower cost device due to a reduction in distinct components which may be sourced from different vendors, which may provide a reduced manufacturing burden (i.e. reduced packaging, assembly, etc.). According to the present invention, a needle serves multiple purposes, namely as a lancet and a transfer tube, all in a single device. This insures that a sterile skin-piercing member is used for each and every test, thereby reducing the risk on infection and/or pain associated with lancet reuse, as well as simplified operation.
A further possible advantage provided by the present invention is the elimination of spreading/filtering media or layer. This advantage eliminates the reliance on a special spreading media which can reduce the volume of blood available to the reagent, thereby providing an opportunity for even greater sample volume reduction and related pain reduction. The elimination of a spreading/filtering media or layer also simplifies manufacturing, for example, by reducing the necessity of correctly positioning a small spreading media layer relative to other components of the assembly.
According to one aspect of the present invention, there is provided an arrangement comprising: a needle comprising a first end and a second end opposite the first end, and a lumen having an inner diameter; and at least one fluid transport enhancing projection disposed in the lumen of the needle and extending from the second end toward the first end.
According to a further aspect, the present invention provides an arrangement comprising: a base having a bore disposed therein extending from a first surface of the base through a second surface of the base; a fluid transport tube having a first end, a second end opposite the first end, and a lumen having an inner diameter, the second end of the tube being received within the bore of the base; at least one fluid transport enhancing projection disposed in the lumen of the tube and extending from the second end toward the first end; and an analyte quantification member in fluid communication with the bore.
According to yet another aspect, the present invention provides a wearable blood glucose monitor comprising any of the arrangements described herein.
The preferred embodiments are illustrated in the drawings in which like reference numerals refer to the like elements and in which:
Devices, arrangements and their associated methods are structured to comprise one or more of the following characteristics.
An exemplary arrangement 100 formed consistent with the principles of the present invention is illustrated in
The arrangement 100 may further include a base 20. The base 20 may have any suitable geometry or size. In the embodiment demonstrated in
The arrangement 100 includes a fluid transport enhancing projection 30. The fluid transport enhancing projection 30 is located in the lumen 16 of the tube 10 or needle 18. The projection 30 preferably extends from the second end 16 toward the first end 14 of the tube 10 or needle 18. The distance that the projection 30 may extend into lumen 16, toward the first end 12 may vary widely according to the teachings of the present invention. For example, the projection 30 may extend from 0 to 100%, preferably 75%, of the longitudinal length of the tube 10 or needle 18; however, this projection should not go beyond the beveled surfaces B of a needle 18 such that it would interact with the skin during the lancing process. For a given lumen 16 inner diameter, the longer the projection 30 the smaller the volume of fluid needed to effect transport. Alternatively, according to the present invention the projection 30 may extend down into the portion of the bore indicated at 22e, but terminates before extending past the second end 14 of the tube 10 or needle 18 and into the lumen 16. In other words, according to this embodiment of the present invention, the projection 30 extends 0% of the longitudinal length of the lumen 16 of the tube 10 or needle 18.
The projection 30 may be provided in many different forms. For example, as illustrated in
According to one alternative embodiment, the projection 30 may be formed as a distinct and separate member of the base 20, and may be provided generally in the form of a wire (See, e.g.,
According to a further alternative embodiment, the projection 30, whether integral with the base or formed as a separate member, can be provided with a fluid transport enhancing surface feature, such as a PDMS or a Silwet coating or a surface texturing applied to at least a portion of the surface of projection 30.
The projection 30 is preferably formed from a non-fibrous material. Alternatively, the projection 30 is formed from a relatively non-porous material. The projection 30 may be formed of any suitable material, such as metal or plastic material. According to one alternative embodiment, the projection 30 is formed from a hydrophilic polymer, such as polycarbonate. Forming the projection 30 of such a material provides the added benefit of increased fluid transport capabilities due to the hydrophilic nature of the material.
The projection 30 is provided with a transverse cross-sectional dimension, which is less than the inner diameter of the lumen 16. In other words, the projection 30 occupies some, but not all, of the cross-sectional area defined by the inner lumen 16 of the tube 10 or needle 18. The interaction between fluid traveling within the lumen 16 with the reduced cross-sectional area is believed to provide enhanced capillary action that pulls the fluid further along the path toward the second end 14, and ultimately the second surface 26 of the base 20. The ratio between the cross-sectional area of the lumen 16 and the projection 30 can be varied by changing one or more of the inner diameter of the tube 10 or needle 18, and transverse cross-sectional dimension, or outer diameter, of the projection 30. If the difference in cross-sectional area between the lumen 16 and the projection 30 is too small, no flow will occur due the high resistance to flow caused by a capillary passageway defined by the inner diameter of the lumen and the projection 30 that is too small. The above-described dimensions can be readily varied, and optimized depending upon numerous factors, such as the nature of fluid being transported. When the fluid to be transported is comprised of mainly whole blood, according to one non-limiting example of the present invention, the lumen may be provided with an inner diameter on the order of 0.012 inches, and the projection 30 may be provided with a transverse cross-sectional dimension on the order of 0.0065 inches. It has been observed that an arrangement provided with this construction successfully transports blood samples having volumes ranging from about 200-500 nl.
The projection 30 provides numerous advantages and benefits compared with arrangements with the prior art. For example, the above-described arrangement is operable to transport a sample of fluid having a volume that is insufficient to fill the entire volume of the defined by the lumen 16 of tube 10 or needle 18. The enhanced powerful capillary action created by the projection 30 is believed to facilitate the transfer of volumes of fluid, which are less than the volume of the above-described lumen 16. In addition, the fluid transport mechanism is not dependent upon flow of the fluid through the voids defined within the interior of a porous or fibrous material, which can be time consuming and reduces the volume of fluid available for analysis and may alter the composition of the blood components (i.e., change hematocrit) in unpredictable ways. The enhanced flow that enables transport smaller volumes of fluid advantageously permits working with smaller sample volumes. This is important in certain applications, such as lancing operations to draw a sample of blood from the skin. The ability to utilize smaller sample volumes in turn enables the adoption of lancing techniques that minimize pain and intrusiveness to the patient as well as the potential need for milking of blood from the wound to the surface of the skin. In addition, the ability to transport a smaller sample volume, as well as a lack of dependence upon flow through a porous or fibrous material, also enables a quicker overall transport operation, and in turn, permits a quicker overall testing procedure, which is also advantageous to the user.
The arrangement 100 may further comprise and analyte quantification member 32. The analyte quantification member 32 may be provided in many different forms. In general, the analyte quantification member 32 may be in the form of a member that provides quantification by any suitable technique, such as electro-chemical or photometric analysis. According to one exemplary embodiment, the analyte quantification member 32 comprises an assay pad or membrane, which contains one or more chemical reagents selected to react with a predetermined analyte, thereby producing a readable signal. For example, as illustrated in
According to one embodiment, the analyte quantification member 32 is in fluid communication with the bore 22. According to another embodiment, the analyte quantification member 32 is in direct fluid communication with the bore 22. In other words, there are no additional components or features intervening between the bore 22, which opens at the second surface 26, and at least one surface of the analyte quantification member 32. This arrangement is beneficial in that the fluid may be transported from the lumen 16 and or bore 22 directly to the analyte quantification member 32, thereby enabling a quicker overall fluid transport operation than some arrangements of the prior art, such as those arrangements which include one or more intervening layers between the analyte quantification member 32 and a fluid transport channel or passageway.
The arrangement 100 may further comprise a means for securing the analyte quantification member 32 to the base 20. Suitable means for securing include an adhesive provided between the analyte quantification member 32 and the base 20, one or more recess features provided on the base 20 which trap the quantification member 32 therein, transparent adhesive tape placed over the quantification member 32, or an integral or separate cover member disposed on the base overlying the quantification member 32. One exemplary embodiment of such a cover is illustrated in
An alternative arrangement 200 of the present invention is illustrated in
A further alternative arrangement 300 is depicted in
Further details concerning the at least one groove 44 are provided in related application Ser. No. ______, entitled DEVICES AND METHODS FOR FACILITATING FLUID TRANSPORT, Attorney docket no. 023095.0120PTUS, filed on even date with the present application, the entire content of which is incorporated by reference herein.
A further alternative arrangement 500 constructed according to the principles of the present invention is depicted in
An integrated device for sampling and testing a sample of body fluid for analyte concentration formed according to the principles of the present invention may have a number of suitable configurations. According to certain embodiments the device is configured to perform testing by acquiring a sample of blood from the user, transfer the sample to an analysis site, and determine the concentration of glucose contained therein. These operations are all performed with little or no user input. For example, these operations may commence automatically according to a specified or predetermined schedule. Alternatively, these operations may commence at the command of the user via, for example, pressing a start button on the device.
The device may include disposable and reusable portions. The disposable portion may include at least one skin piercing element/transport member and analysis site (which may include an assay pad). The disposable portion may provide the capability to perform a single test. After testing is complete, the disposable portion is discarded and replaced with a new disposable portion before performing another test. Alternatively, the disposable portion includes a plurality of skin piercing elements/transport members and analysis sites. Such disposable units permit a plurality of tests to be performed before it is necessary to discard and replace the disposable unit. The device may be either wearable or handheld, or both.
A non-limiting exemplary integrated device is illustrated in
The device 600 preferable includes at least one arrangement for performing a measurement of the concentration of an analyte contained in a sample of blood. According to the illustrated embodiment, the device 600 comprises at least one arrangement 606 having features as described herein, including a hub-like base, at least one skin-piercing element, at least one fluid-transport enhancing projection, and at least one analysis site which may contain an assay pad. The at least one arrangement 606 may form part of a disposable portion or unit. According to one embodiment, the disposable unit allows for at least one measurement of the concentration of an analyte contained in a sample of blood prior to being discarded and replaced. According to a further embodiment, the disposable unit allows for a plurality of measurements of the concentration of an analyte contained in a sample of blood prior to being discarded and replaced.
All of the above-described exemplary arrangements of the present invention may be used independently, or in combination with other devices and arrangements, and systems. Inclusion in other types of devices, wearable and non-wearable, are specifically contemplated by the present invention. Additional details of such discrete autonomous integrated testing devices may be gathered from the disclosure of U.S. patent application Ser. No. ______, entitled DEVICE FOR FLUID ANALYSIS WITH SAMPLE EXTRACTION AND TRANSPORT, Attorney Docket No. 023095.0118PLUS, the entire content of which is incorporated herein by reference.
According to the present invention, there is also provided methods for improving the transport of fluid. The present invention also provides methods for improving the transport of body fluid within a transport tube or needle by enhancing the capillary transport properties of the lumen of the tube or needle.
According to one aspect, the present invention provides a method of improving transport of a fluid, such as a body fluid, comprising: providing a needle having a first end and a second end opposite the first end, and a lumen having an inner diameter; and introducing at least one fluid transport enhancing projection into the lumen of the needle such that the projection extends from the second end toward the first end.
According to another aspect, the present invention provides a method for improving transport of a fluid, such as a body fluid, comprising: providing a base having a bore disposed therein extending from a first surface of the base through a second surface of the base; providing a fluid transport tube having a first end, a second end opposite the first end, and a lumen having an inner diameter, and introducing at least the second end of the tube within the bore of the base; introducing at least one fluid transport enhancing projection into the lumen of the tube such that the projection extends from the second end toward the first end; and providing an analyte quantification member in fluid communication with the bore.
According to the present invention, any of the above-described methods may further comprise providing the needle with a first end that is constructed for piercing the skin, forming the needle or tube from a metal, and forming the at least one projection from a polymeric material or a metal.
The above-described methods may further comprise extending the bore beyond the second end of the tube or needle, wherein the portion of the bore extending from the second end of the tube or needle to the second surface optionally comprises a fluid transport enhancing feature, such as at least one of a coating and a surface texturing. Alternatively, the second end of the tube or needle is disposed such that it is substantially coplanar with the second surface.
In any of the above-described methods, the at least one projection may be formed as an integral extension of the base. Alternatively, the projection may be formed as a wire.
According to the methods of the present invention, the quantification member is disposed such that it is in direct fluid communication with the bore. The quantification member may be formed of a fibrous membrane containing a chemical reagent chosen to react with a predetermined analyte.
Methods of the present invention may further include providing a cover overlying the quantification member. The cover may be constructed to permit optical communication with the quantification member; for example, the cover may be formed entirely of a transparent or translucent material.
In any of the above-described methods, at least one groove may also be provided in the second surface of the base such that it is in fluid communication with the bore.
According to the methods of the present invention, a wearable or hand held blood glucose monitor can be formed and/or operated by a method comprising, at least in part, any of the above-described methods.
While this invention is satisfied by embodiments in many different forms, as described in detail in connection with preferred embodiments of the invention, it is understood that the present disclosure is to be considered as exemplary of the principles of the invention and is not intended to limit the invention to the specific embodiments illustrated and described herein. Numerous variations may be made by persons skilled in the art without departure from the spirit of the invention. The scope of the invention will be measured by the appended claims and their equivalents. The abstract and the title are not to be construed as limiting the scope of the present invention, as their purpose is to enable the appropriate authorities, as well as the general public, to quickly determine the general nature of the invention. In the claims that follow, unless the term “means” is used, none of the features or elements recited therein should be construed as means-plus-function limitations pursuant to 35 U.S.C. §112, ¶6
Claims
1. An arrangement comprising:
- a needle comprising a first end and a second end opposite the first end, and a lumen having an inner diameter and a longitudinal length; and
- at least one fluid transport enhancing projection extending 0-100% of the longitudinal length of the lumen of the needle and extending toward the first end.
2-42. (canceled)
Type: Application
Filed: Dec 31, 2010
Publication Date: Apr 28, 2011
Applicant: Intuity Medical, Inc. (Sunnyvale, CA)
Inventors: Jeffrey L. Emery (Redwood City, CA), Jeffrey M. Jones (Sunnyvale, CA), Raul Escutia (Santa Clara, CA), Stephen M. Yee (Sunnyvale, CA)
Application Number: 12/983,078
International Classification: A61B 5/15 (20060101);