Device and method employing shape memory alloy

• US 6,916,159 B2
• Filed: 10/09/2003
• Issued: 07/12/2005
• Est. Priority Date: 10/09/2002
• Status: Expired due to Term

• Current Assignee: Therasense Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Therasense Incorporated (Abbott Laboratories Incorporated)
• Inventors: Reggiardo, Christopher V., Rush, Benjamin M.
• Primary Examiner(s): Tyler, Cheryl
• Assistant Examiner(s): Solak, Timothy P.
• Application Number:
  US10/683,659
• Publication Number:
  US 20040115067A1
• Time in Patent Office: 642 Days
• Field of Search: 417/321, 417/410.1, 417/416, 417/417
• US Class Current: 417/321
• CPC Class Codes: A61M 2205/0266 Shape memory materials
• CPC Class Codes: A61M 2205/0288 Electro-rheological or magneto-rheological materials
• CPC Class Codes: A61M 2205/3317 Electromagnetic, inductive or dielectric measuring means
• CPC Class Codes: A61M 2205/702 automatically during use
• CPC Class Codes: A61M 5/14216 Reciprocating piston type
• CPC Class Codes: A61M 5/14244 adapted to be carried by the patient, e.g. portable on the body
• CPC Class Codes: F03G 7/065 using a shape memory element
• CPC Class Codes: F04B 13/00 Pumps specially modified to deliver fixed or variable measured quantities
• CPC Class Codes: F04B 17/03 driven by electric motors
• CPC Class Codes: F04B 19/22 of reciprocating-piston type
• CPC Class Codes: F04B 2205/09 Flow through the pump
• CPC Class Codes: F04B 43/043 Micropumps
• CPC Class Codes: F04B 43/08 having tubular flexible members F04B43/12 takes precedence
• CPC Class Codes: F04B 49/065 and making use of computers
• CPC Class Codes: F04B 51/00 Testing machines, pumps, or pumping installations
• CPC Class Codes: F05C 2251/08 Shape memory
• CPC Class Codes: G01F 11/021 of the piston type G01F11/04 takes precedence

Abstract

A system for the metering and delivery of small discrete volumes of liquid is comprised of a small or minimal number of inexpensive components. One such component is a movable member, such as a miniature precision reciprocating displacement pump head, which is driven by an actuator that comprises a shape memory alloy material. The operating mechanism of the system is of little or minimal complexity. The system facilitates the precise metering and delivery of the small discrete volumes of liquid. Potential applications for the system include subcutaneous, long-term, automated drug delivery, for example, the delivery of insulin to a person with diabetes. In such an application, the small, simple and inexpensive nature of the invention would allow for its use as both a portable and a disposable system.

Claims

1. A device for pumping a predetermined volume of fluid comprising:

a cavity operably associated with an inlet and an outlet, the inlet of a construction sufficient for operable communication with a source of fluid, the cavity at least partially defined by a resilient housing;

an inlet check valve operably associated with the inlet and an outlet check valve operably associated with the outlet;

a member operably associated with the resilient housing, the member disposed in a first position by way of a biasing force and moveable therefrom to a second position, the member sufficient to fully compress the resilient housing when in one of the first position and the second position, and sufficient to fully decompress the resilient housing when in a different one of the first position and the second position;

a biasing element operably associated with the member and of a construction sufficient to provide the biasing force;

an actuator comprising a shape memory alloy, the actuator operably associated with the member and of a construction sufficient to move the member from the first position to the second position when the shape memory alloy undergoes a dimensional change relative to an original condition thereof, and sufficient to move the member from the second position to the first position when the shape memory alloy returns toward the original condition;

wherein, when the inlet is in operable communication with the source of fluid, the cavity is empty of the predetermined volume of fluid when the resilient housing is fully compressed and the cavity is filled with the predetermined volume of fluid when the resilient housing is fully decompressed.

2. The device of claim 1, wherein, when the inlet is in operable communication with the source of fluid, the cavity is filled with the predetermined volume of fluid when the member is in the first position and empty of the predetermined volume of fluid when the member is in the second position.

3. The device of claim 1, wherein, when the inlet is in operable communication with the source of fluid, the cavity is empty of the predetermined volume of fluid when the member is in the first position and being filled with the predetermined volume of fluid when the member is in the second position.

4. The device of claim 1, wherein the resilient housing comprises a tube.

5. The device of claim 1, wherein the resilient housing comprises a tube, the inlet comprises an inlet end of the tube, and the outlet comprises an outlet end of the tube.

6. The device of claim 1, wherein the resilient housing comprises a diaphragm.

7. The device of claim 1, wherein the resilient housing comprises a diaphragm sealed to a substrate, the inlet is operably associated with the substrate, and the outlet is operably associated with the substrate.

8. The device of claim 1, wherein at least one of the inlet check valve and the outlet check valve comprises an elastomeric valve of a construction sufficient for being press-fit into a corresponding one of the inlet and the outlet.

9. The device of claim 1, wherein at least one of the inlet check valve and the outlet check valve comprises an elastomeric valve of low cracking pressure.

10. The device of claim 1, wherein at least one of the inlet check valve and the outlet check valve comprises an elastomeric valve of a construction sufficient to from a fluid-tight seal in the absence of back pressure.

11. The device of claim 1, wherein the biasing element comprises the shape memory alloy.

12. The device of claim 1, wherein the shape memory alloy is sufficient to move the member in one direction when the shape memory undergoes the dimensional change, and sufficient to move the member in an opposite direction when the shape memory alloy returns toward the original condition.

13. The device of claim 1, wherein the dimensional change is reversible, the member returning to the first position by way of the biasing force when the dimensional change is reversed.

14. The device of claim 1, wherein the dimensional change is repeatable, the member movable from the first position to the second position at least two times.

15. The device of claim 1, wherein a volume of the source of fluid diminishes concomitantly as fluid flows therefrom.

16. The device of claim 1, wherein the fluid is a drug.

17. The device of claim 1, wherein the fluid is insulin.

18. The device of claim 17, the device sufficient to pump the predetermined volume of insulin substantially without damage.

19. The device of claim 17, the device sufficient to pump the predetermined volume of insulin substantially without damage over a period of three days.

20. The device of claim 17, the device sufficient to pump the predetermined volume of insulin up to 3000 times.

21. The device of claim 1, wherein the predetermined volume of fluid is in a range of 0.5 microliter to 5 microliters.

22. The device of claim 1, further comprising a housing for the cavity, the member, and the actuator, the housing of a construction sufficient for wearing by a user.

23. The device of claim 1, further comprising a housing for the cavity, the member, the actuator, the inlet, and the source, the housing of a construction sufficient for wearing by a user.

24. The device of claim 22 or claim 23, the housing comprising an adhesive sufficient for adhesion to the skin of a user.

25. The device of claim 1, further comprising:

a source of electrical energy operably connected to the shape memory alloy of the actuator; and

a pulse-generating circuit operably connected to the source of electrical energy.

26. The device of claim 25, wherein the pulse-generating circuit is programmable.

27. The device of claim 25, the pulse-generating circuit comprising:

a battery, a capacitor, a timing circuit, and a transistor switch, wherein the battery and capacitor are operably connected to each other in parallel, the connector is operably connected to the shape memory alloy of the actuator via the transistor switch, and the timing circuit is operably connected to the battery and the transistor switch.

28. The device of claim 27, wherein the capacitor is of lower equivalent series resistance than the battery.

29. The device of claim 27, wherein, when the transistor switch is closed, electrical energy is provided to the shape memory alloy of the actuator primarily via the capacitor.

30. The device of claim 27, wherein the timing circuit is programmable.

31. The device of claim 25, the pulse-generating circuit comprising:

a battery, a capacitor, a signal converter, a timing circuit, and a transistor switch, wherein the battery and capacitor are operably connected to each other in parallel via the converter, the capacitor is operably connected to the shape memory alloy of the actuator via the transistor switch, and the timing circuit is operably connected to the battery and the transistor switch.

32. The device of claim 31, wherein the signal converter is sufficient for allowing the capacitor to be charged to an equal or greater extent than the battery.

33. The device of claim 31, wherein the signal converter comprises a DC to DC converter.

34. The device of claim 31, wherein the transistor switch is sufficient for modulation to transmit electrical energy in at least one pulse.

35. The device of claim 31, further comprising an inductor and a diode, wherein the capacitor is operably connected to the shape memory alloy of the actuator via the transistor switch, the inductor, and the diode.

36. The device of claim 35, wherein the inductor and the diode are sufficient to allow electrical energy to flow through the shape memory alloy of the actuator after the transistor switch, modulated to transmit electrical energy in at least one pulse, is open.

37. The device of claim 31, wherein the timing circuit is programmable.

46. The device of any of claims 1 and 23, further comprising the source of fluid.

38. A method of pumping a predetermined volume of fluid, comprising:

providing a cavity operably associated with an inlet and an outlet, the cavity at least partially defined by a resilient housing;

providing an inlet check valve operably associated with inlet, and an outlet check valve operably associated with the outlet;

providing a member in a first position under bias via a biasing element;

providing a shape memory alloy operably associated with the member;

providing at least one pulse of electricity to the shape memory alloy to move the member to a second position; and

ceasing the providing of at least one pulse of electricity to the shape memory alloy to return the member to the first position;

the resilient housing being fully compressed when the member is in one of the first position and the second position, and being fully decompressed the resilient housing when the member is in a different one of the first position and the second position;

wherein, when the inlet is in operable communication with a source of fluid, the cavity is empty of the predetermined volume of fluid when the resilient housing is fully compressed and the cavity is filled with the predetermined volume of fluid when the resilient housing is fully decompressed.

39. The method of claim 38, further comprising cycling through said providing at least one pulse of electricity to the shape memory alloy and said ceasing the providing of at least one pulse of electricity to the shape memory alloy.

40. The method of claim 38, wherein said providing at least one pulse of electricity to the shape memory alloy and said ceasing the providing of at least one pulse of electricity to the shape memory alloy are programmatically controlled.

47. The method of any of claims 38 and 41, further comprising providing the source of fluid.

48. The method of any of claims 38 and 42, wherein the at least one pulse comprises more than one pulse.

41. A method of pumping a predetermined volume of fluid, comprising:

providing a cavity operably associated with an inlet and an outlet, the cavity at least partially defined by a resilient housing;

providing an inlet check valve operably associated with the inlet, and an outlet check valve operably associated with the outlet;

providing a member in a first position under bias via a biasing element;

providing a shape memory alloy operably associated with the member;

increasing the temperature of the shape memory alloy to move the member to a second position; and

after said increasing, decreasing a temperature of the shape memory alloy to return the member to the first position;

the resilient housing being fully compressed when the member is in one of the first position and the second position, and being fully decompressed the resilient housing when the member is in a different one of the first position and the second position;

wherein, when the inlet is in operable communication with a source of fluid, the cavity is empty of the predetermined volume of fluid when the resilient housing is fully compressed and the cavity is filled with the predetermined volume of fluid when the resilient housing of fully decompressed.

42. The method of claim 41, wherein said increasing the temperature of the shape memory alloy comprises providing at least one pulse of electricity.

43. The method of claim 42, wherein said decreasing the temperature of the shape memory alloy comprises ceasing the providing of at least one pulse of electricity.

44. The method of claim 41, further comprising cycling through said increasing the temperature of the shape memory alloy and said decreasing the temperature of the shape memory alloy.

45. The method of claim 41, said increasing the temperature of the shape memory alloy and said decreasing the temperature of the shape memory alloy are programmatically controlled.