Shape memory alloy wire driven positive displacement micropump with pulsatile output

• US 20030198558A1
• Filed: 04/22/2002
• Published: 10/23/2003
• Est. Priority Date: 04/22/2002
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Stutz, William H. Jr., Nason, Clyde K., Yap, Darren Y.
• Granted Patent: US 7,052,251 B2
• Time in Patent Office: Days
• US Class Current: 417/53
• CPC Class Codes: A61M 2005/14268 with a reusable and a disposable component
• CPC Class Codes: A61M 2205/0266 Shape memory materials
• 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 5/14248 of the skin patch type
• CPC Class Codes: F04B 17/00 Pumps characterised by combination with, or adaptation to, specific driving engines or motors
• CPC Class Codes: F04B 19/006 Micropumps F04B43/043 and F04B43/095 take precedence
• CPC Class Codes: F05C 2251/08 Shape memory

Abstract

Apparatuses and methods for pumping fluid are disclosed. An exemplary apparatus is a miniature pump that includes a shape memory wire that obtains a plastic condition below a transformation temperature and has a memorized shape such that the shape memory wire produces a work stroke by returning to the memorize shape at least at the transformation temperature. A spring biased against the shape memory wire is deflected by the work stroke to deform the shape memory wire from the memorized shape below the transformation temperature. A fluid pump is coupled to the shape memory wire and driven by the biased spring and shape memory wire to produce a fluid flow. The miniature pump can be incorporated into a self-contained infusion device in the form of a compact self-adhesive patch including a fluid reservoir, control electronics and power supply that is place directly at the infusion site of a user.

Claims

1. An apparatus, comprising:

a shape memory wire capable attaining at least two different material conditions, a first material condition below a transformation temperature and a second material condition above a transformation temperature, wherein the wire attains a memorized configuration such that the wire can produce a work stroke as a consequence of a transition between the first and second material conditions;

a spring biased against the wire to be deflected by the work stroke which deforms the wire from the memorized configuration when the wire attains the first material condition; and

a reciprocating fluid pump coupled to the wire and driven by the biased spring and wire to produce a fluid flow.

2. The apparatus of claim 1, wherein the fluid pump receives fluid from a reservoir and drives the fluid out through a conduit.

3. The apparatus of claim 1, wherein the fluid pump is in a cylindrical form smaller than approximately 25 mm in diameter and 25 mm long.

4. The apparatus of claim 1, wherein the fluid pump delivers fluid medication from a reservoir to a user.

5. The apparatus of claim 1, wherein the shape memory wire has an extended effective length in a doubled back configuration.

6. The apparatus of claim 1, wherein the shape memory wire is elongated when deformed and contracts to the memorized shape at and above the transformation temperature.

7. The apparatus of claim 1, wherein the fluid pump includes a valved chamber and a piston, wherein the valved chamber expands and contracts with movement of the piston.

8. The apparatus of claim 7, wherein fluid is driven out of the valved chamber by the bias spring as it deforms the shape memory wire and moves the piston.

9. The apparatus of claim 7, wherein fluid is driven out of the valved chamber by the work stroke of the shape memory wire as it overcomes the bias spring and moves the piston.

10. The apparatus of claim 7, wherein the valved chamber includes a diaphragm.

11. The apparatus of claim 7, wherein the valved chamber includes at least one valve selected from the group comprising a rubber flap valve, a ball valve, a metal reed valve, a ball poppet valve and a spring loaded valve.

12. The apparatus of claim 7, wherein the valved chamber includes an inlet valve for receiving fluid from a reservoir and an outlet valve for driving the fluid out to a conduit.

13. The apparatus of claim 12, wherein the outlet valve is disposed on the piston.

14. The apparatus of claim 12, wherein the inlet valve is disposed on the piston.

15. The apparatus of claim 12, wherein the outlet valve is disposed on a wall of the chamber.

16. The apparatus of claim 12, wherein the inlet valve is disposed on a wall of the chamber.

17. The apparatus of claim 1, further comprising a power supply coupled to the shape memory wire to thermoelectrically induce at least the transformation temperature in the wire.

18. The apparatus of claim 17, wherein the power supply is a direct current (DC) battery.

19. The apparatus of claim 1, further comprising an electronic timing circuit to control the fluid flow by controlling application of the power supply to the shape memory wire to repeat the work stroke.

20. The apparatus of claim 19, wherein the electronic timing circuit varies a fluid flow rate by varying a number of work strokes repeated in a time period.

21. The apparatus of claim 19, wherein the electronic timing circuit is programmed to vary the fluid flow based upon a user prescription.

22. A fluid delivery system, comprising:

a reservoir;

a miniature pump receiving a fluid from the reservoir and driving the fluid out a conduit;

an electronic circuit for controlling delivery of the fluid with the pump;

a compact shell enclosure housing the reservoir, pump and electronic circuit; and

an infusion set directly coupled to the conduit;

wherein the compact shell enclosure can be coupled directly to an infusion site of a user for medication delivery through the infusion set.

23. The fluid delivery system of claim 22, wherein the miniature pump delivers fluid medication from a reservoir to a user.

24. The fluid delivery system of claim 22, wherein the miniature pump is in a cylindrical form smaller than approximately 25 mm in diameter and 25 mm long.

25. The fluid delivery system of claim 22, wherein the reservoir comprises a collapsible bag.

26. The fluid delivery system of claim 22, further comprising an adhesive material attached to the compact shell enclosure for holding the system to a user'"'"'s skin.

27. The fluid delivery system of claim 22, wherein the electronic circuit is in a reusable electronics module.

28. The fluid delivery system of claim 27, wherein the reusable electronics module is preprogrammed to control delivery of the fluid per a user'"'"'s prescription.

29. The fluid delivery system of claim 22, wherein the pump is actuated by a shape memory wire that obtains a plastic condition below a transformation temperature and has a memorized shape such that the wire produces a work stroke by substantially returning to the memorized shape at and above the transformation temperature and wherein a spring is biased against the wire to be deflected by the work stroke and the spring deforms the wire in the plastic condition from the memorized shape.

30. The fluid delivery system of claim 29, wherein the electronic timing circuit varies a fluid flow rate by varying a number of work strokes repeated in a time period.

31. The fluid delivery system of claim 29, wherein the wire is elongated when deformed by the spring and contracts to the memorized shape at and above the transformation temperature.

32. The fluid delivery system of claim 29, wherein the shape memory wire has an extended effective length in a doubled back configuration.

33. The fluid delivery system of claim 29, further comprising a power supply coupled to the wire to thermoelectrically induce at least the transformation temperature in the wire.

34. The fluid delivery system of claim 33, wherein the power supply is a direct current (DC) battery.

35. The fluid delivery system of claim 33, wherein the electronic timing circuit controls the fluid flow by controlling application of the power supply to the shape memory wire to repeat the work stroke.

36. The fluid delivery system of claim 29, wherein the pump includes a valved chamber and a piston, wherein the valved chamber expands and contracts with movement of the piston.

37. The fluid delivery system of claim 36, wherein the fluid is driven out of the valved chamber by the spring as it deforms the wire and moves the piston.

38. The fluid delivery system of claim 36, wherein the fluid is driven out of the valved chamber by the work stroke of the shape memory wire as it overcomes the spring and moves the piston.

39. The fluid delivery system of claim 36, wherein the valved chamber includes a diaphragm.

40. The fluid delivery system of claim 36, wherein the valved chamber includes at least one valve selected from the group comprising a rubber flap valve, a ball valve, a metal reed valve, a ball poppet valve and a spring loaded valve.

41. The fluid delivery system of claim 36, wherein the valved chamber includes an inlet valve for receiving fluid from the reservoir and an outlet valve for driving the fluid out the conduit.

42. The fluid delivery system of claim 41, wherein the outlet valve is disposed on the piston.

43. The fluid delivery system of claim 41, wherein the inlet valve is disposed on the piston.

44. The fluid delivery system of claim 41, wherein the outlet valve is disposed on a wall of the chamber.

45. The fluid delivery system of claim 41, wherein the inlet valve is disposed on a wall of the chamber.

46. A method of pumping fluid, comprising the steps of:

heating an shape memory wire to a recovery temperature equal or greater than a transformation temperature of the shape memory wire;

returning the shape memory wire to a memorized shape, overcoming the bias spring and drawing fluid into a valved chamber at the recovery temperature;

cooling the shape memory wire to a reset temperature below the transformation temperature; and

deforming the shape memory wire and driving the fluid out of the valved chamber below the reset temperature with the bias spring.

47. The method of claim 46, where the fluid is drawn into the valved chamber from a reservoir and is driven out of the valved chamber through a conduit.

48. The method of claim 46, wherein the fluid comprises a medication.

49. The method of claim 46, wherein the shape memory wire has an extended effective length in a doubled back configuration.

50. The method of claim 46, wherein the valved chamber includes a diaphragm.

51. The method of claim 46, wherein the valved chamber includes at least one valve selected from the group comprising a rubber flap valve, a ball valve, a metal reed valve, a ball poppet valve and a spring loaded valve.

52. The method of claim 46, wherein the valved chamber operates with a piston and the fluid is drawn into the valved chamber through an inlet valve and driven out of the valved chamber through an outlet valve.

53. The method of claim 52, wherein the outlet valve is disposed on the piston.

54. The method of claim 52, wherein the inlet valve is disposed on the piston.

55. The method of claim 52, wherein the outlet valve is disposed on a wall of the chamber.

56. The method of claim 52, wherein the inlet valve is disposed on a wall of the chamber.

57. The method of claim 46, wherein heating the shape memory wire is performed by coupling a power supply coupled to the shape memory wire.

58. The method of claim 46, further comprising controlling a fluid flow with an electronic timing circuit to control heating of the shape memory wire.

59. The method of claim 58, wherein the electronic timing circuit varies a fluid flow rate by varying a number of work strokes repeated in a time period.

60. The method of claim 58, wherein the electronic timing circuit is programmed to vary the fluid flow based upon a user prescription.

61. A method of pumping fluid, comprising the steps of:

using a bias spring to deform a shape memory wire coupled to a valved chamber so that fluid is drawn into the valved chamber at a reset temperature below the transformation temperature of the shape memory wire;

heating the shape memory wire to a recovery temperature equal or greater than the transformation temperature;

returning the shape memory wire to a memorized shape at the recovery temperature, overcoming the bias spring and driving fluid out of the valved chamber; and

allowing the shape memory wire to return to the reset temperature.

62. The method of claim 61, where the fluid is drawn from a reservoir into the valved chamber and is driven out of the valved chamber through a conduit.

63. The method of claim 61, wherein the fluid comprises a medication.

64. The method of claim 61, wherein the shape memory wire has an extended effective length in a doubled back configuration.

65. The method of claim 61, wherein the valved chamber includes a diaphragm.

66. The method of claim 61, wherein the valved chamber includes at least one valve selected from the group comprising a rubber flap valve, a ball valve, a metal reed valve, a ball poppet valve and a spring loaded valve.

67. The method of claim 61, wherein the valved chamber operate with a piston and the fluid is drawn into the valved chamber through an inlet valve and driven out of the valved chamber through an outlet valve.

68. The method of claim 67, wherein the outlet valve is disposed on the piston.

69. The method of claim 67, wherein the inlet valve is disposed on the piston.

70. The method of claim 67, wherein the outlet valve is disposed on a wall of the chamber.

71. The method of claim 67, wherein the inlet valve is disposed on a wall of the chamber.

72. The method of claim 61, wherein heating the shape memory wire is performed by coupling a power supply coupled to the shape memory wire.

73. The method of claim 61, further comprising controlling a fluid flow with an electronic timing circuit to control heating of the shape memory wire.

74. The method of claim 73, wherein the electronic timing circuit varies a fluid flow rate by varying a number of work strokes repeated in a time period.

75. The method of claim 73, wherein the electronic timing circuit is programmed to vary the fluid flow based upon a user prescription.