Dual Latching Microvalves
A valve for use in connection with microfluidic devices includes a safety feature such that flow is controlled even in the case of a loss of power, thus having applications in critical applications such as the precise delivery of drugs over time. The valve may be used in connection with multiple tubes delivering drugs, and may be used with a pump, such as an electrochemical pump, to provide the force to move the fluids containing drugs for delivery. In certain applications, more than one medicine may be delivered and metered independently using a single pump with multiple reservoirs and valves.
This application is a continuation of U.S. patent application Ser. No. 15/503,310, filed on Feb. 10, 2017 and entitled “Dual Latching Microvalves,” which is the US national phase of international patent application no. PCT/US2015/045251 filed on Aug. 14, 2015, which in turned claimed the benefit of U.S. provisional patent application No. 62/037,474, filed on Aug. 14, 2014, and entitled “Multifunctional Microvalves.” Such applications are incorporated herein by reference in their entirety.
BACKGROUNDThe field of the invention is valves for microfluidic applications, and in particular to the use of such microvalves for safe and controlled delivery of fluids from a reservoir.
Fluidic microvalves can be constructed from shape-memory alloys. For example,
U.S. Pat. No. 7,260,932 teaches a fluid control pinch valve using shape memory alloy that receives a current to open or close the pinch valve. Similarly, U.S. Pat. No. 6,843,465 teaches a shape-memory wire actuated control valve, in which the shape-memory wire is connected to an electrical platform and mechanically coupled to a transfer mechanism. The actuator is actuated by conducting electrical current through the shape-memory wire causing the wire to contract and thereby actuating the transfer mechanism, which is operably coupled to the fluid control valve such that actuating and de-actuating the transfer mechanism opens and closes the valve. U.S. Pat. No. 6,742,761 teaches a poppet valve that is used for opening and closing a miniature latching valve by means of an actuator mechanism that includes a shape-memory alloy wire. The change in shape of the shape-memory alloy wire causes the poppet to either move toward or away from the valve seat, thereby either closing or opening the valve. U.S. Pat. No. 6,840,257 teaches a proportional valve using a shape-memory alloy actuator, with a shutter axially movable from and towards a valve seat under the control of a shape-memory alloy actuating member.
Valves are a critical component of microfluidic systems. Miniaturized valves can be used in combination with miniaturized pumps to deliver pulsed and/or constant flow of microliter or nanoliter volumes of solution (or less). The valves themselves must be small and use little power to activate. Additional power can be saved by using a latching valve that does not require power to remain in any one state. Latching valves are not designed in a normally open or normally closed state; rather they can rest in either state. In drug delivery and other applications, latching valves are an important safety feature when properly configured as they prevent a direct flow path from a large reservoir to a patient in the case of a system failure.
BRIEF SUMMARYThe present invention relates generally to a valve and systems for using valves for controlled delivery of fluid and to provide a failsafe whereby the state of the valve is maintained despite a loss of power or other failure. This provides, in certain embodiments, certain advantages in applications such as the precise delivery of medicines to a patient over time. In certain embodiments, the valve may be used in connection with multiple tubes delivering drugs, and may be used with a pump, such as an electrochemical pump, to move the fluids containing drugs for delivery. In certain applications, more than one medicine may be delivered and metered independently using a single pump with multiple reservoirs and valves.
These and other features, objects and advantages of the disclosed subject matter will become better understood from a consideration of the following detailed description, drawings, and claims directed to the invention. This brief summary and the following detailed description and drawings are exemplary only, and are intended to provide further explanation of various implementations without limiting the scope of the invention as set forth in the claims.
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Although various embodiments of the invention have been described herein with reference to particular applications related to the delivery of fluids and in particular drugs, it will be apparent that the invention is not so limited. In addition, the dual valve safety mechanism can be realized with a ratcheting action, or an appropriately shaped cam, for example. Furthermore, any actuation mechanism can be used to switch valve states of coupled valves including solenoid, magnetic, pneumatic or hydraulic controls, stepping motor, or manual operation. In addition, the preceding description has focused on two-dimensional layouts of the sliding or pivoting members, however, it can be extended to acting members which are arranged in a non-planar manner. Larger or smaller embodiments of a dual latching valve could be used for safety-enhanced flow control at any scale.
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Alternatively, by arranging the inlet line 805 and outlet line 817 to both run through valve arm 401 and the outlet line 807 and inlet line 815 to both run through valve arm 404, then only one dual latching valve is needed to provide flow from reservoir 801 to the patient 821. In this arrangement as well, at no time is there an open fluid flow path from the reservoir to the patient.
The following steps describe how a metered dose of fluid is delivered in a near continuous fashion from reservoir 801 to the patient. In this case, the system has already been primed so that both fluid paths are full of fluid. In step (1), inlet valve 401 and outlet valve 414 are open and outlet valve 404 and inlet valve 411 are closed. When the ePump 825 is activated, it first pulls fluid from the drug reservoir 801 through flow path 805 and into chamber 806 where it is stored. Simultaneously, ePump 825 expels fluid stored in chamber 816 through path 817 and into the patient. In step (2), the valves are reversed such that output valve 404 and input valve 411 are open and input valve 401 and output valve 414 are closed. In this case, the pump draws fluid from the reservoir 801 through flow path 815 and into chamber 816 where it is stored. Simultaneously, the metered volume of fluid stored in chamber 806 (from step 1) is expelled through flow path 807 into the patient. Repeating of Steps 1 and 2 will result in near continuous (or intermittent) and safe delivery of controlled doses of fluid (in this case, a drug) to the patient.
Although various embodiments of the invention have been described herein with reference to particular applications related to the delivery of fluids and in particular drugs, it will be apparent that the invention is not so limited, and instead will find application in other fields where the precise delivery of fluids is desired in a fail-safe manner. Furthermore, although certain embodiments of the invention have been described for use in connection with an ePump, it will be apparent that the invention is not so limited, and that other types of pumps could be used in connection with the valves of the invention as described herein. In addition, although nitinol has been used as the shape-memory alloy in certain embodiments described herein, it will be understood that other shape-memory alloys or materials or actuation methods could be substituted therefor within the scope of the invention.
Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any systems and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, a limited number of the exemplary systems and materials are described herein. It will be apparent to those skilled in the art that many more modifications are possible without departing from the invent concepts herein. All terms used herein should be interpreted in the broadest possible manner consistent with the context. Any ranges expressed herein are intended to include all particular values within the stated range, as well as all sub-ranges that fall within the stated range.
The present invention has been described with reference to the foregoing specific implementations. These implementations are intended to be exemplary only, and not limiting to the full scope of the present invention. Many variations and modifications are possible in view of the above teachings. The invention is intended to be limited only as set forth in the appended claims.
Claims
1. A valve mechanism for delivering a first drug to a patient, comprising:
- a. a first dual latching valve;
- b. a second dual latching valve; and
- c. a dual sided pump fluidically connected to the first dual latching valve and second dual latching valve for near-continuous delivery of the first drug to the patient.
2. The valve mechanism of claim 1, further comprising a first drug reservoir fluidically connected to the dual sided pump, wherein the mechanism is configured by placement of the first dual latching valve and second dual latching valve such that there is never a direct fluidic path from the first drug reservoir to the patient.
3. The valve mechanism of claim 2, wherein the first dual latching valve and second dual latching valve are configured to provide intermittent delivery of multiple doses of the first drug to a patient.
4. The valve mechanism of claim 2, further comprising a second reservoir for holding a second drug, wherein the second reservoir is fluidically connected to the dual sided pump, and wherein the first dual latching valve and second dual latching valve are configured to control independent delivery of the first drug and the second drug to the patient.
5. The valve mechanism of claim 4, wherein the first dual latching valve and second dual latching valve are configured to deliver multiple doses of the first drug from the first reservoir to the patient with fewer or no doses of the second drug from the second reservoir to the patient.
6. The valve mechanism of claim 4, wherein the first dual latching valve and second dual latching valve are configured to create a mixing action between the first reservoir and the second reservoir.
7. The valve mechanism of claim 4, wherein the dual sided pump is an electrochemical pump.
8. The valve mechanism of claim 4, wherein the first dual latching valve and second dual latching valve are connected through an actuation mechanism such that both the first dual latching valve and second dual latching valve cannot be open simultaneously.
9. The valve mechanism of claim 8, wherin the actuation mechanism comprises a cam or a ratchet to open the first dual latching valve and close the second dual latching valve in a first position, and to close the first dual latching valve and open the second dual latching valve in a second position, as the cam or ratchet rotates around an axis.
10. A dual latching cam microvalve, comprising:
- a. a first valve arm;
- b. a first compressible tube adjacent to the first valve arm;
- c. a first valve seat adjacent to the first tube to form, together with the first valve arm and the first tube, a first valve;
- d. a second valve arm;
- e. a second compressible tube adjacent to the second valve arm;
- f. a second valve seat adjacent to the second tube to form, together with the second valve arm and the second tube, a second valve;
- g. a cam positioned to rotate around an axis between a first position and a second position, wherein rotation of the cam to the first position engages the second valve arm end to close the second tube and allow the first tube to open, and rotation of the cam to the second position engages the first valve arm end to close the first tube and allow the second tube to open, such that both tubes are never open at the same time;
- h. one or more actuation mechanisms attached to the cam to rotate the cam between the first and second position; and
- i. at least one electrical power source electrically connected to the at least one actuation mechanism.
11. The dual latching cam microvalve of claim 10, further comprising:
- a. a first resilient member engaged with the first valve arm to bias the first valve arm end towards the first valve seat; and
- b. a second resilient member engaged with the second valve arm to bias the second valve arm end towards the second valve seat.
12. The dual latching cam microvalve of claim 10, further comprising:
- a. a first resilient member engaged with the first valve arm to bias the first valve arm end away from the first valve seat; and
- b. a second resilient member engaged with the first valve arm to bias the second valve arm end away from the second valve seat.
13. The dual latching cam microvalve of claim 11, wherein the first and second resilient members comprise one or more springs.
14. The dual latching cam microvalve of claim 12, wherein the first and second resilient members comprise one or more springs.
15. The dual latching cam microvalve of claim 10, wherein the one or more actuation mechanisms are selected from the set consisting of shape memory alloy wires, a solenoid, a motor, a pneumatic actuator, and a hydraulic actuator.
16. The dual latching cam microvalve of claim 10, further comprising at least one additional valve arm controlled by a cam shaped to start and stop a fluid movement through more than one fluidic pathway in a coordinated manner.
17. The dual latching cam microvalve of claim 10, wherein both the first valve and second valve are applied to a single flow path through the first and second tubes wherein one of the first and second valves must be closed when the other of the first and second valves is open.
18. The dual latching cam microvalve of claim 17, further comprising:
- a. a reservoir for holding a fluid; and
- b. a dosing chamber fluidically connected to a reservoir by the first tube, wherein when the first valve is open and the second valve is closed, the fluid is drawn from the reservoir to a dosing chamber, and when the second valve is open and the first valve is closed, the fluid is pushed from the dosing chamber into a patient.
19. The dual latching cam microvalve of claim 18, wherein the fluid comprises a drug, and wherein a maximum volume of the dosing chamber is sized to accommodate a medically efficacious quantity of the drug being delivered to the patient.
20. The dual latching cam microvalve of claim 19, wherein delivery of the drug from the dosing chamber is timed based on an input signal.
21. A valve mechanism for delivering a first drug and a second drug to a patient, comprising:
- a. a first dual latching cam microvalve;
- b. a second dual latching cam microvalve;
- c. a dual-sided pump fluidically connected to the first dual latching cam microvalve and second dual latching cam microvalve for independent delivery of either the first or second drugs to the patient;
- d. a first drug reservoir fluidically connected to the first dual latching cam microvalve and a first side of the dual-sided pump; and
- e. a second drug reservoir fluidically connected to the second dual latching cam microvalve and a second side of the dual-sided pump.
22. The valve mechanism of claim 21, wherein the first drug and second drug are the same.
23. The valve mechanism of claim 21, wherein the first drug and second drug are different.
24. The valve mechanism of claim 21, wherein the first dual latching cam microvalve and second dual latching cam microvalve are configured to deliver multiple doses of the first drug from the first reservoir to the patient and to deliver fewer or no doses of the second drug from the second reservoir.
25. The valve mechanism of claim 21, wherein the dual-sided pump is an electrochemical pump.
26. The valve mechanism of claim 21, wherein the first dual latching cam microvalve and the second dual latching cam microvalve are connected through an actuation mechanism such that both the first dual latching cam microvalve and the second dual latching cam microvalve cannot be open to the patient simultaneously.
Type: Application
Filed: Jun 10, 2019
Publication Date: Sep 26, 2019
Inventors: Forrest W. Payne (Fayetteville, AR), Greg Lamps (Smyrna, GA), Champak Das (Fayetteville, AR), Sai Kumar (Johns Creek, GA), Ashley Shemain (Flowery Branch, GA)
Application Number: 16/436,627