Device and Method Employing Shape Memory Alloy

• US 20100241076A1
• Filed: 09/21/2009
• Published: 09/23/2010
• Est. Priority Date: 10/09/2002
• Status: Abandoned Application

• 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.
• Application Number:
  US12/563,798
• Publication Number:
  US 20100241076A1
• Time in Patent Office: Days
• 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 device for pumping a predetermined volume of fluid, comprising:

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

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

a flexible diaphragm operably associated with the cavity, the diaphragm flexed to a first position by a biasing force and reverse flexed therefrom to a second position, wherein the diaphragm flexes to compress the cavity that collapses when in the first position, and to decompress the cavity when in the second position;

a biasing element operably associated with the diaphragm to provide the biasing force;

an actuator including a NiTi alloy having a first transition temperature and a second transition temperature, wherein the actuator operably associated with the diaphragm flexes the diaphragm from the first position to the second position when the NiTi alloy thermally transforms at the first transition temperature, and flexes the diaphragm from the second position to the first position when the NiTi alloy thermally transforms at the second transition temperature and returns toward the original condition; and

wherein the diaphragm draws fluid into the cavity when the diaphragm flexes from the first position to the second position, and the diaphragm expels fluid from the cavity when the diaphragm flexes from the second position to the first position.

2. A device for pumping a predetermined volume of fluid according to claim 1, wherein the diaphragm is a flexible, resilient membrane that changes the volume of the cavity.

3. A device for pumping a predetermined volume of fluid according to claim 1, wherein the collapsible enclosure is resilient.

4. A device for pumping a predetermined volume of fluid according to claim 3, wherein the resilient enclosure includes a balloon.

5. A device for pumping a predetermined volume of fluid according to claim 4, wherein the balloon is disposable and detachable from a housing containing the cavity, diaphragm, biasing element, and actuator.

6. A device for pumping a predetermined volume of fluid according to claim 1, wherein the fluid includes insulin.

7. A device for pumping a predetermined volume of insulin, comprising:

a reservoir enclosure for holding the insulin;

a displacement cavity bounded by a flexible diaphragm in communication with the reservoir enclosure;

inlet and outlet valves and respective conduits physically discrete from the cavity and in communication with the cavity;

a plunger acting on the diaphragm to compress or decompress the insulin in the cavity;

a biasing element acting on the plunger to bias the plunger to a first position compressing the cavity;

a shape memory actuator, having a first transition temperature to a high temperature phase with a remembered configuration and a second transition temperature to a low temperature phase with a malleable configuration, coupled to the plunger;

an electrical source providing a current to the shape memory actuator, wherein a current on state transforms the shape memory actuator to the high temperature phase and moves the plunger against the biasing element to a second position decompressing the cavity, and a current off state allows the shape memory actuator to cool to the low temperature phase so that the biasing element urges the plunger to the first position; and

wherein the enclosure is physically discrete and detachable from a housing containing the cavity, plunger, and biasing element.

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

a variable volume displacement cavity partially bounded by a flexible diaphragm;

a fluid inlet and a fluid outlet in communication with the cavity;

a plunger linked to the diaphragm wherein the diaphragm is wetted by the fluid and the plunger is not wetted;

a biasing element linked to the plunger moving the plunger to a first position compressing the fluid in the cavity;

a shape memory actuator, having a first transition temperature to a high temperature phase with a remembered configuration and a second transition temperature to a low temperature phase with a malleable configuration, linked to the plunger;

an electrical source providing a current to the shape memory actuator, wherein a current on state transforms the shape memory actuator to the high temperature phase and moves the plunger against the biasing element to a second position, and a current off state allows the shape memory actuator to cool to the low temperature phase so that the biasing element moves the plunger to the first position; and

wherein the movement of the plunger reciprocates the diaphragm flexing to pump the predetermined volume of fluid through the fluid outlet.

9. A device for pumping a predetermined volume of fluid according to claim 8, wherein the fluid includes insulin.

10. A device for pumping a predetermined volume of fluid according to claim 8, wherein the electrical source provides current pulses to the shape memory actuator.

11. A device for pumping a predetermined volume of fluid according to claim 8, wherein the current on and current off states define one cycle, which cycle dispenses periodic dosages of the predetermined volume of fluid.

12. A device for pumping a predetermined volume of fluid according to claim 8, wherein the electrical source includes a programmable pulse generating circuit.

13. A device for pumping a predetermined volume of fluid according to claim 12, wherein the device includes an energy storage cell powering the programmable pulse generating circuit.

14. A device for pumping a predetermined volume of fluid according to claim 13, wherein the energy storage cell includes a battery.

15. A device for pumping a predetermined volume of fluid according to claim 13, wherein the energy storage cell includes a capacitor.

16. A device for pumping a predetermined volume of fluid according to claim 8, wherein the shape memory actuator includes a NiTi wire.

17. A device for pumping a predetermined volume of fluid according to claim 8, wherein the device includes a source of fluid contained in a resilient enclosure.

18. A device for pumping a predetermined volume of fluid according to claim 17, wherein the resilient enclosure includes a collapsible balloon.

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

a fluid displacement cavity partially bounded by a flexible diaphragm;

a reservoir in communication with the fluid displacement cavity;

a plunger engaging the diaphragm wherein the diaphragm is wetted by the fluid and the plunger is dry;

a biasing element linked to the plunger moving the plunger to a first position compressing the fluid in the cavity;

a shape memory actuator, having a high temperature phase with a remembered configuration and a low temperature phase with a malleable configuration, linked to the plunger;

a programmable pulse generating circuit providing pulsed currents to the shape memory actuator, wherein a current on state heat transforms the shape memory actuator to the high temperature phase and moves the plunger against the biasing element to a second position, and a current off state allows the shape memory actuator to cool to the low temperature phase so that the biasing element moves the plunger to the first position, the heating and cooling defining a single actuation cycle; and

wherein the single actuation cycle reciprocates the plunger one stroke, flexing the diaphragm to pump the predetermined volume of fluid through the fluid outlet.