Device and method employing shape memory alloy

• US 8,075,527 B2
• Filed: 11/02/2009
• Issued: 12/13/2011
• 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: Rush, Benjamin M., Reggiardo, Christopher V.
• Primary Examiner(s): Lucchesi, Nicholas
• Assistant Examiner(s): Berdichevsky, Aarti B
• Application Number:
  US12/610,890
• Publication Number:
  US 20100114073A1
• Time in Patent Office: 771 Days
• Field of Search: 604/65, 604/67, 604/122, 604/131, 604/134, 604/151, 604/152, 604/154
• US Class Current: 604/151
• 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 diabetes management system for treating a patient, comprising:

a blood glucose monitor for collecting blood glucose levels in the patient;

an insulin pump having a plunger being disposed adjacent a displacement cavity, the displacement cavity having a diaphragm with a wetted surface and a non-wetted surface, the plunger being in contact with the non-wetted surface of the diaphragm;

a shape memory alloy wire attached to the plunger to impart reciprocating movement to the plunger;

a timing circuit for activating the shape memory alloy wire including an electrical energy storage device for providing electrical energy to the shape memory alloy wire;

a reservoir containing a fluid and being in fluid communication with the displacement cavity so that as the shape memory wire imparts movement to the plunger, the diaphragm reacts to the movement of the plunger to expand and thereby pull a predetermined volume of fluid from the reservoir into the cavity; and

a remote unit for wirelessly communicating with the blood glucose monitor and the insulin pump.

2. The diabetes management system 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 diabetes management system of claim 2, wherein the plunger moves a predetermined amount corresponding to a maximum volume within the displacement cavity.

4. The diabetes management system of claim 1, wherein the shape memory alloy wire cools and a biasing spring associated with the wire moves the plunger a predetermined amount corresponding to the minimum volume within the displacement cavity.

5. The diabetes management system of claim 1, wherein the timing circuit is programmable.

6. The diabetes management system of claim 1, wherein the electrical energy storage device is an electrochemical capacitor having a high capacitance and low-equivalent series resistance.

7. The diabetes management system of claim 1, wherein the rate of fluid delivery is controlled by varying the period of time between actuations of the shape memory alloy wire.

8. The diabetes management system of claim 1, wherein the blood glucose monitor and at least a portion of the insulin pump are disposable with the exception of the electronics including the timing circuit and the shape memory alloy wire.

9. The diabetes management system of claim 1, wherein the insulin pump and the timing circuit are integrated into a single housing.

10. The diabetes management system of claim 9, wherein the insulin pump is disposable and the shape memory alloy wire, timing circuit, and electrical energy storage device are reusable.

11. The diabetes management system of claim 1, wherein the diaphragm is elastomeric.

12. The diabetes management system of claim 11, wherein the plunger has a flat head for attachment to the non-wetted surface of the elastomeric diaphragm.

13. The diabetes management system of claim 12, wherein as the shape memory alloy wire is heated by electrical energy from the electrical energy storage device, the wire shortens and moves the plunger in a first direction thereby pulling on the non-wetted surface of the diaphragm and pulling insulin out of the reservoir and into the displacement cavity.

14. The diabetes management system of claim 13, wherein as the shape memory alloy wire cools, a biasing spring moves the plunger in a second direction thereby pushing the plunger on the non-wetted surface of the diaphragm to push insulin out of the displacement cavity and into the patient.

15. The diabetes management system of claim 1, wherein the insulin reservoir is collapsible.

16. The diabetes management system of claim 1, wherein the insulin pump includes an electrical energy source.

17. The diabetes management system of claim 16, wherein the electrical energy source is a replaceable battery.

18. The diabetes management system of claim 17, wherein the battery is substantially electrically isolated from the shape memory alloy wire.

19. The diabetes management system of claim 18, wherein the battery provides electrical energy to the electrical energy storage device.

20. The diabetes management system of claim 19, wherein the electrical energy storage device is a capacitor.

21. The diabetes management system of claim 17, wherein the battery provides electrical energy to the timing circuit.

22. The diabetes management system of claim 21, wherein the timing circuit is a programmable digital timing circuit.

23. The diabetes management system of claim 22, wherein the timing circuit includes a transistor switch.

24. The diabetes management system of claim 23, wherein the electrical energy storage device is a capacitor.

25. The diabetes management system of claim 24, 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.

26. The diabetes management system of claim 25, wherein the battery charges the capacitor with electrical energy when the transistor switch is open.

27. The diabetes management system of claim 26, wherein the capacitor provides electrical energy to the shape memory alloy wire when the transistor switch is closed.

28. The diabetes management system of claim 1, wherein the shape memory alloy wire is up to 40 mm long.

29. The diabetes management system of claim 1, wherein the shape memory alloy wire is 125 microns in diameter.

30. The diabetes management system of claim 1, wherein the plunger is attached to the shape memory alloy wire.

31. The diabetes management system of claim 1, wherein the plunger pumps 0.1 microliter of insulin into the patient per each pump cycle.

32. The diabetes management system of claim 31, wherein the insulin pump has an effective maximum of 3000 cycles.

33. The diabetes management system of claim 1, wherein the timing circuit generates an electrical pulse duration lasting about 0.15 seconds.

34. A diabetes management system for treating a patient, comprising:

a blood glucose monitor for collecting blood glucose levels in the patient;

an insulin pump having a plunger being disposed adjacent a displacement cavity, the displacement cavity having a diaphragm with a wetted surface and a non-wetted surface, the plunger being in contact with the non-wetted surface of the diaphragm;

a nickel-titanium shape memory alloy wire having a high transition temperature for transforming to a high temperature phase, and a low transition temperature for transforming to a low temperature phase, wherein the wire is attached to the plunger to impart reciprocating movement to the plunger via phase transformations;

a timing circuit for activating the shape memory alloy wire including an electrical energy storage device for providing electrical energy to the shape memory alloy wire to thermally transform the wire from the low temperature phase to the high temperature phase;

a reservoir containing a fluid and being in fluid communication with the displacement cavity so that as the shape memory wire imparts movement to the plunger, the diaphragm reacts to the movement of the plunger to expand and thereby pull a predetermined volume of fluid from the reservoir into the cavity; and

a remote control unit wirelessly communicating with the blood glucose monitor and the insulin pump.

35. The diabetes management system of claim 34, wherein the electrical energy heats the shape memory alloy wire to a transitional temperature thereby causing the wire to shorten.

36. The diabetes management system of claim 35, wherein the plunger moves a predetermined amount corresponding to a maximum volume within the displacement cavity.

37. The diabetes management system of claim 34, wherein the shape memory alloy wire cools and a biasing spring associated with the wire moves the plunger a predetermined amount corresponding to the minimum volume within the displacement cavity.

38. The diabetes management system of claim 34, wherein the timing circuit is programmable.

39. The diabetes management system of claim 34, wherein the electrical energy storage device is an electrochemical capacitor having a high capacitance and low-equivalent series resistance.

40. The diabetes management system of claim 34, wherein the rate of fluid delivery is controlled by varying the period of time between actuations of the shape memory alloy wire.

41. The diabetes management system of claim 34, wherein the blood glucose monitor and at least a portion of the insulin pump are disposable with the exception of the electronics including the timing circuit and the shape memory alloy wire.

42. The diabetes management system of claim 34, wherein the insulin pump and the timing circuit are integrated into a single housing.

43. The diabetes management system of claim 42, wherein the insulin pump is disposable and the shape memory alloy wire, timing circuit, and electrical energy storage device are reusable.

44. The diabetes management system of claim 34, wherein the diaphragm is elastomeric.

45. The diabetes management system of claim 44, wherein the plunger has a flat head for attachment to the non-wetted surface of the elastomeric diaphragm.

46. The diabetes management system of claim 45, wherein as the shape memory alloy wire is heated by electrical energy from the electrical energy storage device, the wire shortens and moves the plunger in a first direction thereby pulling on the non-wetted surface of the diaphragm and pulling insulin out of the reservoir and into the displacement cavity.

47. The diabetes management system of claim 46, wherein as the shape memory alloy wire cools, a biasing spring moves the plunger in a second direction thereby pushing the plunger on the non-wetted surface of the diaphragm to push insulin out of the displacement cavity and into the patient.

48. The diabetes management system of claim 34, wherein the insulin reservoir is collapsible.

49. The diabetes management system of claim 34, wherein the insulin pump includes an electrical energy source.

50. The diabetes management system of claim 49, wherein the electrical energy source is a replaceable battery.

51. The diabetes management system of claim 50, wherein the battery is substantially electrically isolated from the shape memory alloy wire.

52. The diabetes management system of claim 51, wherein the battery provides electrical energy to the electrical energy storage device.

53. The diabetes management system of claim 52, wherein the electrical energy storage device is a capacitor.

54. The diabetes management system of claim 50, wherein the battery provides electrical energy to the timing circuit.

55. The diabetes management system of claim 54, wherein the timing circuit is a programmable digital timing circuit.

56. The diabetes management system of claim 55, wherein the timing circuit includes a transistor switch.

57. The diabetes management system of claim 56, wherein the electrical energy storage device is a capacitor.

58. The diabetes management system of claim 57, 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.

59. The diabetes management system of claim 58, wherein the battery charges the capacitor with electrical energy when the transistor switch is open.

60. The diabetes management system of claim 59, wherein the capacitor provides electrical energy to the shape memory alloy wire when the transistor switch is closed.

61. The diabetes management system of claim 34, wherein the shape memory alloy wire is up to 40 mm long.

62. The diabetes management system of claim 34, wherein the shape memory alloy wire is 125 microns in diameter.

63. The diabetes management system of claim 34, wherein the plunger is attached to the shape memory alloy wire.

64. The diabetes management system of claim 34, wherein the plunger pumps 0.1 microliter of insulin into the patient per each pump cycle.

65. The diabetes management system of claim 64, wherein the insulin pump has an effective maximum of 3000 cycles.

66. The diabetes management system of claim 34, wherein the timing circuit generates an electrical pulse duration lasting about 0.15 seconds.

67. A diabetes management system for treating a patient, comprising:

a blood glucose monitor for collecting blood glucose levels in the patient;

an insulin pump having a plunger being disposed adjacent a displacement cavity, the displacement cavity having a diaphragm with a wetted surface and a non-wetted surface, the plunger being in contact with the non-wetted surface of the diaphragm;

a nickel-titanium shape memory alloy wire having a high temperature phase and a low temperature phase attached to the plunger, wherein the phase changes impart reciprocating movement to the plunger;

a timing circuit for activating the shape memory alloy wire including an electrical energy storage device for providing electrical energy to the shape memory alloy wire to thermally transform the shape memory alloy wire from the low temperature phase to the high temperature phase;

a battery and capacitor for powering the timing circuit;

a reservoir containing a fluid and being in fluid communication with the displacement cavity so that as the shape memory wire imparts movement to the plunger, the diaphragm reacts to the movement of the plunger to expand and thereby pull a predetermined volume of fluid from the reservoir into the cavity; and

a remote unit for wirelessly communicating with the blood glucose monitor and the insulin pump.