DEVICE AND METHOD EMPLOYING SHAPE MEMORY ALLOY

• US 20100049132A1
• Filed: 09/23/2009
• Published: 02/25/2010
• Est. Priority Date: 10/09/2002
• Status: Active Grant

• Current Assignee: Abbott Diabetes Care Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Abbott Diabetes Care Incorporated (Abbott Laboratories Incorporated)
• Inventors: Reggiardo, Christopher V., Rush, Benjamin M.
• Granted Patent: US 8,172,800 B2
• Time in Patent Office: Days
• US Class Current: 604/152
• CPC Class Codes: A61M 2005/1726 the body parameters being measured at, or proximate to, the infusion site
• 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 2205/3569 sublocal, e.g. between console and disposable
• CPC Class Codes: A61M 2205/3592 using telemetric means, e.g. radio or optical transmission
• 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: A61M 5/16886 for measuring fluid flow rate, i.e. flowmeters
• CPC Class Codes: F04B 2205/09 Flow through the pump
• CPC Class Codes: F04B 43/043 Micropumps
• 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 1/64 by measuring electrical currents passing through the fluid flow; measuring electrical potential generated by the fluid flow, e.g. by electrochemical, contact or friction effects G01F1/58 takes precedence
• CPC Class Codes: G01F 1/708 Measuring the time taken to traverse a fixed distance
• CPC Class Codes: G01F 1/7088 using electrically charged particles as tracers
• CPC Class Codes: G01F 25/10 of flowmeters

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 medical device for pumping a fluid, comprising:

a plunger having reciprocal movement in a displacement cavity between a first limit and a second limit;

a shape memory alloy wire attached to the plunger for pulling the plunger in a first direction in the displacement cavity;

a digital timing circuit for activating the shape memory alloy wire including a capacitor for providing electrical energy to the shape memory alloy wire; and

an insulin reservoir containing insulin and being in fluid communication with the displacement cavity so that as the shape memory alloy wire is activated the wire shortens and pulls the plunger in the first direction thereby drawing a predetermined volume of insulin from the reservoir into the displacement cavity.

2. The medical device of claim 1, wherein the electrical energy heats the shape memory alloy wire to a transitional temperature thereby causing the wire to shorten.

3. The medical device of claim 2, wherein the plunger moves to the first limit corresponding to a maximum volume within the displacement cavity.

4. The medical device of claim 2, wherein the shape memory alloy wire cools and a biasing spring associated with the wire moves the plunger to the second limit corresponding to the minimum volume within the displacement cavity.

5. The medical device of claim 1, wherein the digital timing circuit is programmable.

6. The medical device of claim 1, wherein the capacitor is an electrochemical capacitor having a high capacitance and low-equivalent series resistance.

7. The medical device of claim 1, wherein the rate of insulin delivery is controlled by varying the period of time between actuations of the shape memory alloy wire.

8. The medical device of claim 1, wherein a portion of the pump is disposable with the exception of the electronics including the digital timing circuit and the shape memory alloy wire.

9. The medical device of claim 1, wherein the insulin reservoir is collapsible.

10. The medical device of claim 1, wherein the pump includes an electrical energy source.

11. The medical device of claim 10, wherein the electrical energy source is a replaceable battery.

12. The medical device of claim 11, wherein the battery is electrically connected to the shape memory alloy wire.

13. The medical device of claim 12, wherein the battery provides electrical energy to the capacitor.

14. The medical device of claim 13, wherein the capacitor is connected in parallel with the battery.

15. The medical device of claim 14, wherein electrical energy is supplied to the shape memory wire primarily from the capacitor due to the substantially lower equivalent series resistance as compared to the battery.

16. The medical device of claim 1, wherein the battery provides electrical energy to the timing circuit.

17. The medical device of claim 1, wherein the timing circuit is a programmable digital timing circuit.

18. The medical device of claim 17, wherein the timing circuit includes a transistor switch.

19. The medical device of claim 13, wherein the battery and the capacitor are connected to each other in parallel and are connected to the shape memory alloy wire through the transistor switch.

20. The medical device of claim 19, wherein the battery charges the capacitor with electrical energy when the transistor switch is open.

21. The medical device of claim 20, wherein the capacitor provides electrical energy to the shape memory alloy wire when the transistor switch is closed.

22. The medical device of claim 1, wherein the shape memory alloy wire is up to 40 mm long.

23. The medical device of claim 1, wherein the shape memory alloy wire is 125 microns in diameter.

24. The medical device of claim 1, wherein the plunger is attached to the shape memory alloy wire.

25. The medical device of claim 1, wherein the plunger pumps 0.1 microliter of insulin into the patient per each pump cycle.

26. The medical device of claim 25, wherein the insulin pump has an effective maximum of 3000 cycles.

27. The medical device of claim 1, wherein the timing circuit generates an electrical pulse duration lasting about 0.15 seconds.

43. The medical device of claim 1, wherein the electrical energy heats the shape memory alloy wire to a transitional temperature thereby causing the wire to shorten.

44. The medical device of claim 2, wherein the plunger moves to the first limit corresponding to a maximum volume within the displacement cavity.

45. The medical device of claim 2, wherein the shape memory alloy wire cools and a biasing spring associated with the wire moves the plunger to the second limit corresponding to the minimum volume within the displacement cavity.

46. The medical device of claim 1, wherein the digital timing circuit is programmable.

28. A medical device for pumping a fluid, comprising:

a plunger having reciprocal movement in a displacement cavity between a first limit and a second limit;

a shape memory alloy wire attached to the plunger for moving the plunger in a first direction in the displacement cavity;

a digital timing circuit for activating the shape memory alloy wire including a capacitor for providing electrical energy to the shape memory alloy wire; and

an reservoir containing insulin and being in fluid communication with the displacement cavity so that as the shape memory alloy wire is activated the wire changes length thereby moving the plunger in the first direction thereby drawing a predetermined volume of insulin from the reservoir into the displacement cavity.

29. The medical device of claim 28, wherein the electrical energy heats the shape memory alloy wire to a transitional temperature thereby causing the wire to shorten.

30. The medical device of claim 29, wherein the plunger moves to the first limit corresponding to a maximum volume within the displacement cavity.

31. The medical device of claim 29, wherein the shape memory alloy wire cools and a biasing spring associated with the wire moves the plunger to the second limit corresponding to the minimum volume within the displacement cavity.

32. The medical device of claim 28, wherein the digital timing circuit is programmable.

33. The medical device of claim 28, wherein the capacitor is an electrochemical capacitor having a high capacitance and low-equivalent series resistance.

34. The medical device of claim 28, wherein the rate of insulin delivery is controlled by varying the period of time between actuations of the shape memory alloy wire.

35. The medical device of claim 28, wherein a portion of the pump is disposable with the exception of the electronics including the digital timing circuit and the shape memory alloy wire.

36. A medical device for pumping a fluid, comprising:

a plunger having reciprocal movement in a tubular-shaped displacement cavity between a first limit and a second limit;

a shape memory alloy wire attached to the plunger for moving the plunger in a first direction in the displacement cavity;

a digital timing circuit for activating the shape memory alloy wire including a capacitor for providing electrical energy to the shape memory alloy wire; and

an insulin reservoir containing insulin and being in fluid communication with the displacement cavity so that as the shape memory alloy wire is activated the wire shortens and pulls the plunger in the first direction thereby drawing a predetermined volume of insulin from the reservoir into the tubular-shaped displacement cavity.

37. The medical device of claim 36, wherein the electrical energy heats the shape memory alloy wire to a transitional temperature thereby causing the wire to shorten.

38. The medical device of claim 37, wherein the plunger moves to the first limit corresponding to a maximum volume within the tubular-shaped displacement cavity.

39. The medical device of claim 37, wherein the shape memory alloy wire cools and a biasing spring associated with the wire moves the plunger to the second limit corresponding to the minimum volume within the tubular-shaped displacement cavity.

40. The medical device of claim 36, wherein the digital timing circuit is programmable.

41. The medical device of claim 36, wherein the capacitor is an electrochemical capacitor having a high capacitance and low-equivalent series resistance.

42. A medical device for pumping a fluid, comprising:

a plunger having reciprocal movement in a displacement cavity between a first limit and a second limit;

a shape memory alloy wire attached to the plunger for pulling the plunger in a first direction in the displacement cavity;

a digital timing circuit for activating the shape memory alloy wire including a battery for providing electrical energy to the shape memory alloy wire; and

an insulin reservoir containing insulin and being in fluid communication with the displacement cavity so that as the shape memory alloy wire is activated the wire shortens and pulls the plunger in the first direction thereby drawing a predetermined volume of insulin from the reservoir into the displacement cavity.

47. The medical device of claim 42, wherein the battery is electrically connected to a capacitor.

48. The medical device of claim 47, wherein the capacitor is an electrochemical capacitor having a high capacitance and low-equivalent series resistance.

49. The medical device of claim 47, wherein the battery is connected in parallel to the capacitor.

50. The medical device of claim 49, wherein the capacitor is electrically connected to the shape memory alloy wire.

51. The medical device of claim 50, wherein the capacitor provides electrical energy to the shape memory alloy wire.

52. The medical device of claim 42, wherein the battery provides electrical energy to the timing circuit.

53. The medical device of claim 47, wherein the timing circuit is a programmable digital timing circuit.

54. The medical device of claim 53, wherein the timing circuit includes a transistor switch.

55. The medical device of claim 47, wherein the battery and the capacitor are connected to each other in parallel and are connected to the shape memory alloy wire through the transistor switch.

56. The medical device of claim 55, wherein the battery charges the capacitor with electrical energy when the transistor switch is open.

57. The medical device of claim 56, wherein the capacitor provides electrical energy to the shape memory alloy wire when the transistor switch is closed.

58. The medical device of claim 42, wherein the shape memory alloy wire is up to 40 mm long.

59. The medical device of claim 42, wherein the shape memory alloy wire is 125 microns in diameter.

60. The medical device of claim 42, wherein the plunger is attached to the shape memory alloy wire.

61. The medical device of claim 42, wherein the plunger pumps 0.1 microliter of insulin into the patient per each pump cycle.

62. The medical device of claim 61, wherein the insulin pump has an effective maximum of 3000 cycles.

63. The medical device of claim 42, wherein the timing circuit generates an electrical pulse duration lasting about 0.15 seconds.

64. The medical device of claim 42, wherein the rate of insulin delivery is controlled by varying the period of time between actuations of the shape memory alloy wire.

65. The medical device of claim 42, wherein a portion of the pump is disposable with the exception of the electronics including the digital timing circuit and the shape memory alloy wire.