Shape memory alloy wire driven positive displacement micropump with pulsatile output

• US 20070166170A1
• Filed: 03/21/2007
• Published: 07/19/2007
• 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, Yap, Darren, Nason, Clyde
• Granted Patent: US 8,574,215 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. A method of using an apparatus having a housing to deliver a fluid medication to a user, comprising the steps of:

subjecting a shape memory wire within the housing to a first material condition, wherein the wire is 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, and 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; and

subjecting the wire to a second material condition;

wherein the shape memory wire is operatively coupled to a gear within the housing; and

the gear is operatively coupled to a fluid pump within the housing such that when the wire produces the work stroke as a consequence of a transition between the first and second material conditions, the gear is actuated such that the fluid pump generates a fluid flow that delivers the fluid medication from the apparatus to the user.

2. The method of claim 1, further comprising using a fluid medication reservoir contained within the housing as a source of the fluid medication that is delivered to the user.

3. The method of claim 2, wherein the fluid medication within the fluid medication reservoir comprises an insulin.

4. The method of claim 2, wherein the fluid medication reservoir contains an amount of fluid medication suitable for multi-day delivery of the fluid medication from the apparatus to the user.

5. The method of claim 4, wherein the fluid medication reservoir contains an amount of fluid medication suitable for delivery to the user for at least three days.

6. The method of claim 1, wherein the method delivers the fluid medication subcutaneously to the user.

7. The method of claim 1, further comprising using an electronics module within the housing to control fluid medication delivery to the user.

8. The method of claim 6, wherein the electronics module is programmable.

9. The method of claim 1, wherein subjecting the wire to a material condition comprises heating and is performed using a power supply that is operatively coupled to the wire.

10. The method of claim 9, wherein the power supply comprises a battery contained within the housing.

11. The method of claim 10, further comprising delivering the fluid medication using electronic timing circuit contained within the housing that is operatively coupled to the battery and produces a continuous pulsed work stroke that actuates the gear.

12. The method of claim 1, wherein the housing is adapted to be carried by the user.

13. The method of claim 1, further comprising using a sealing member to inhibit water from entering the housing of the apparatus.

14. A method for portably delivering a fluid medication to a user, comprising the steps of:

connecting a portable apparatus having a housing to the user;

subjecting a shape memory wire within the housing of the portable apparatus to a first material condition, wherein the wire is 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, and 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; and

subjecting the wire to a second material condition;

wherein subjecting the wire to a material condition comprises heating and is performed using a power supply within the housing of the portable apparatus that is coupled to the wire; and

wherein the shape memory wire is operatively coupled to a gear within the housing of the apparatus; and

the gear is operatively coupled to a fluid pump within the portable apparatus such that when the wire produces a work stroke as a consequence of a transition between the first and second material conditions, the gear is actuated and the fluid pump generates a fluid flow that delivers the fluid medication from a fluid medication reservoir contained within the portable apparatus to the user as the apparatus is carried by the user.

15. The method of claim 14, wherein power supply comprises a battery that provides a pulsing current to the wire to incrementally heat and cool the wire.

16. The method of claim 14, wherein the fluid medication reservoir contains an amount of fluid suitable for multi-day delivery of the fluid medication from the portable apparatus to the user.

17. The method of claim 14, wherein the method delivers the fluid medication subcutaneously to the user.

18. The method of claim 14, wherein the fluid medication within the fluid medication reservoir comprises an insulin.

19. The method of claim 14, further comprising using a programmable electronics module within the portable apparatus to control fluid medication delivery to the user.

20. The method of claim 14, further comprising using a sealing member to inhibit water from entering the housing of the portable apparatus.