Electroactive polymer devices for moving fluid

• US 20070164641A1
• Filed: 12/21/2006
• Published: 07/19/2007
• Est. Priority Date: 07/20/1999
• Status: Active Grant

• Current Assignee: SRI International, Inc.
• Original Assignee: SRI International, Inc.
• Inventors: Heim, Jonathan, Kornbluh, Roy, Heydt, Richard, Pelrine, Ronald
• Granted Patent: US 7,394,182 B2
• Time in Patent Office: Days
• US Class Current: 310/11
• CPC Class Codes: A61M 2205/0283 Electro-active polymers [EAP]
• CPC Class Codes: A61M 5/142 Pressure infusion, e.g. using pumps
• CPC Class Codes: A61M 5/14212 Pumping with an aspiration and an expulsion action
• CPC Class Codes: A61M 5/14216 Reciprocating piston type
• CPC Class Codes: A61M 5/14224 Diaphragm type
• CPC Class Codes: A61M 5/14236 Screw, impeller or centrifugal type pumps
• CPC Class Codes: A61M 5/14276 specially adapted for implantation
• CPC Class Codes: A61M 60/148 in line with a blood vessel using resection or like techniques, e.g. permanent endovascular heart assist devices
• CPC Class Codes: A61M 60/178 drawing blood from a ventricle and returning the blood to the arterial system via a cannula external to the ventricle, e.g. left or right ventricular assist devices
• CPC Class Codes: A61M 60/196 replacing the entire heart, e.g. total artificial hearts [TAH]
• CPC Class Codes: A61M 60/268 the displacement member being flexible, e.g. membranes, diaphragms or bladders
• CPC Class Codes: A61M 60/454 generated by electro-active actuators, e.g. using electro-active polymers or piezoelectric elements
• CPC Class Codes: A61M 60/894 Passive valves, i.e. valves actuated by the blood
• CPC Class Codes: A63H 3/365 allowing a choice of facial features, e.g. to change the facial expression change of expression through animation A63H3/48, self-moving A63H13/005; movable eyes A63H3/40
• CPC Class Codes: B60G 2400/60 Load
• CPC Class Codes: B60G 2401/11 Electrostrictive transducers
• CPC Class Codes: B60G 2401/23 Memory materials
• CPC Class Codes: B60G 2500/20 Spring action or springs
• CPC Class Codes: F01L 2301/00 Using particular materials
• CPC Class Codes: F02G 1/043 the engine being operated by expansion and contraction of a mass of working gas which is heated and cooled in one of a plurality of constantly communicating expansible chambers, e.g. Stirling cycle type engines
• CPC Class Codes: F02G 2243/52 : acoustic
• CPC Class Codes: F04B 17/00 : Pumps characterised by combination with, or adaptation to, specific driving engines or motors
• CPC Class Codes: F04B 35/00 : Piston pumps specially adapted for elastic fluids and characterised by the driving means to their working members, or by combination with, or adaptation to, specific driving engines or motors, not otherwise provided for
• CPC Class Codes: F04B 35/04 : the means being electric
• CPC Class Codes: F04B 35/045 : using solenoids
• CPC Class Codes: F04B 43/043 : Micropumps
• CPC Class Codes: F04B 43/08 : having tubular flexible members F04B43/12 takes precedence
• CPC Class Codes: F04B 43/084 : the tubular member being deformed by stretching or distortion
• CPC Class Codes: F04B 43/09 : Pumps having electric drive
• CPC Class Codes: F04B 43/095 : Piezoelectric drive
• CPC Class Codes: F04B 43/14 : having plate-like flexible members
• CPC Class Codes: F04D 33/00 : Non-positive-displacement pumps with other than pure rotation, e.g. of oscillating type F04D35/00 takes precedence; hand-held fans A45B
• CPC Class Codes: F05C 2225/08 : Thermoplastics
• CPC Class Codes: F15C 5/00 : Manufacture of fluid circuit elements; Manufacture of assemblages of such elements integrated circuits
• CPC Class Codes: F16F 15/005 : using electro- or magnetostrictive actuation means generating of mechanical vibrations operating with electrostriction B06B1/06, with magnetostriction B06B1/08; vehicle suspension arrangements characterised by use of piezoelectric elements B60G17/01941; piezoelectric, electrostrictive and magnetostrictive devices per se H10N30/00
• CPC Class Codes: F25B 9/14 : characterised by the cycle used, e.g. Stirling cycle
• CPC Class Codes: H02N 11/006 : Motors
• CPC Class Codes: H04R 19/02 : Loudspeakers H04R19/01 takes precedence
• CPC Class Codes: H04R 23/00 : Transducers other than those covered by groups H04R9/00 - H04R21/00 diaphragms for transducers of the distributed-mode type H04R7/045
• CPC Class Codes: Y10S 310/80 : Piezoelectric polymers, e.g. PVDF

Abstract

The invention describes devices for performing thermodynamic work on a fluid, such as pumps, compressors and fans. The thermodynamic work may be used to provide a driving force for moving the fluid. Work performed on the fluid may be transmitted to other devices, such as a piston in a hydraulic actuation device. The devices may include one or more electroactive polymer transducers with an electroactive polymer that deflects in response to an application of an electric field. The electroactive polymer may be in contact with a fluid where the deflection of the electroactive polymer may be used to perform thermodynamic work on the fluid. The devices may be designed to efficiently operate at a plurality of operating conditions, such as operating conditions that produce an acoustic signal above or below the human hearing range. The devices may be used in thermal control systems, such as refrigeration system, cooling systems and heating systems.

Claims

1. A device, comprising:

an inlet fluid line;

a valve housing including an inlet connected to the inlet fluid line, an outlet, and a fluid volume to allow fluid to flow from the inlet to the outlet;

an outlet fluid line connected to the outlet;

a first piece of electroactive material connected to the valve housing; and

circuitry electrically connected to the first piece of electroactive material to apply a first voltage across the first piece of electroactive material to cause the first piece of electroactive material to have a first shape that does not substantially restrict fluid flow through the fluid volume of the valve housing, and to apply a second voltage across the first piece of electroactive material to cause the first piece of electroactive material to have a second shape, the second shape that at least partially restricts the flow of fluid from the inlet through the fluid volume to the outlet.

2. The device of claim 1, wherein the inlet fluid line has a cross sectional area of about 0.00005 square inches or less.

3. A device, comprising:

an inlet fluid line;

a valve housing including an inlet, an outlet, and a fluid volume to allow fluid to flow from the inlet to the outlet;

an outlet fluid line connected to the outlet;

a first piece of electroactive material connected to the valve housing, wherein the valve housing and the first piece of electroactive material comprise a first valve;

circuitry electrically connected to the first piece of electroactive material to apply a first voltage across the first piece of electroactive material to cause the first piece of electroactive material to have a first shape that does not substantially restrict fluid flow through the fluid volume of the valve housing, and to apply a second voltage across the first piece of electroactive material to cause the first piece of electroactive material to have a second shape, the second shape that at least partially restricts the flow of fluid from the inlet through the fluid volume to the outlet;

a pump having an electroactive material, a pump inlet, and a pump outlet the pump inlet connected to the outlet fluid line of the first valve;

a second valve having a second piece of electroactive material and connected to the pump outlet;

a cooling device connected to the second valve to receive fluid pumped by the pump, the fluid received being heated when within the cooling device;

a heat source connected to the cooling device to transfer heat from the heat source to the cooling device;

a heat exchange area connected to the cooling device to receive the heated fluid from the cooling device and to transfer heat to an environment around the heat exchange area; and

wherein the circuitry is also electrically connected to the pump and the second valve to apply voltages to the pump and the first and second valve, the voltages timed to cause the first valve to be closed and the second valve to be open when the material within the pump expands and to cause the first valve to be open and the second valve to be closed with the material within the pump contracts.

4. The device of claim 3, wherein:

the first piece of electroactive material is a sheet of electroactive material;

the first shape of the first piece of electroactive material is that of the sheet curved in an arc with a first arc length; and

the arc of the first shape has a convex surface closer to the fluid volume and a concave surface further from the fluid volume.

5. The device of claim 4, wherein the second shape of the first piece of electroactive material is that of the sheet curved in an arc with a second arc length larger than the first arc length.

6. The device of claim 5, wherein the second shape of the first piece of electroactive material extends at least partially into the fluid volume to at least partially restrict flow of fluid from the inlet through the fluid volume to the outlet.

7. The device of claim 5, wherein the second arc length is greater than the first arc length by about 20% to about 50%.

8. The device of claim 5, wherein second shape of the first piece of electroactive material substantially completely blocks the flow of fluid from the inlet through the fluid volume to the outlet.

9. The device of claim 5, further comprising a second piece of electroactive material connected to the valve housing, and wherein the circuitry is electrically connected to the second piece of electroactive material to apply a third voltage across the first piece of electroactive material to cause the second piece of electroactive material to have a third shape that does not substantially extend into the fluid volume of the valve housing, and to apply a fourth voltage across the second piece of electroactive material to cause the second piece of electroactive material to have a fourth shape, the fourth shape being to cause at least partial constriction of the flow of fluid from the inlet through the fluid volume to the outlet.

10. The device of claim 9, wherein the circuitry is adapted to apply the second voltage across the first piece of electroactive material to cause the first piece of electroactive material to have the second shape, and the fourth voltage across the second piece of electroactive material to cause the second piece of electroactive material to have the fourth shape at approximately the same time, and wherein the second shape of the first piece of electroactive material and the fourth shape of the second of the first piece of electroactive material contact each other to substantially completely block the flow of fluid from the inlet through the fluid volume to the outlet.

11. The device of claim 3, further comprising a restrictor component coupled to the first piece of electroactive material, wherein the second shape of the first piece of electroactive material is to cause the restrictor component to extend at least partially into the fluid volume to at least partially restrict flow of fluid from the inlet through the fluid volume to the outlet.

12. The device of claim 3, wherein the valve housing includes a support structure and a valve seat.

13. A device, comprising:

a diaphragm pump to draw fluid in from a pump inlet and expel fluid out through a pump outlet;

a first valve including an electroactive material to allow fluid to flow into the diaphragm pump when the diaphragm pump draws fluid in from the pump inlet and to at least partially restrict fluid flow when the diaphragm pump expels fluid out through the pump outlet; and

a second valve including an electroactive material to allow fluid to flow from the diaphragm pump when the diaphragm pump expels fluid out through the pump outlet and to at least partially restrict fluid flow when the diaphragm pump draws fluid in from the pump inlet.

14. The device of claim 13, further comprising circuitry to apply voltages to the diaphragm pump and the first and second valves, wherein the electroactive material of the first valve is adapted to take a first shape to allow fluid to flow through the first valve in response to the circuitry applying a first voltage across the electroactive material, and the electroactive material of the first valve is adapted to take a second shape to at least partially restrict fluid from flowing through the first valve in response to the circuitry applying a second voltage across the electroactive material.

15. The device of claim 14, wherein the second voltage is in a range from about 0 V/m to about 440 MV/m.

16. The device of claim 15, wherein the material has a thickness between about 1 micrometer and 2 millimeters.

17. The device of claim 15, wherein the first voltage is about zero volts.

18. The device of claim 14, further comprising a fluid line connected to the first valve and the diaphragm pump to allow fluid to flow between first valve and the diaphragm pump.

19. The device of claim 18, wherein the fluid line has a substantially elliptical cross section.

20. The device of claim 18, wherein the fluid line has a substantially non-circular cross section

21. The device of claim 13, further comprising:

a microprocessor;

a cooling device connected to the microprocessor to receive heat from the microprocessor, and connected to the diaphragm pump; and

wherein the diaphragm pump is adapted to pump fluid through the cooling device, the fluid pumped through the cooling device being to receive heat from the cooling device and remove the heat from the cooling device.

23. The method of claim 21, wherein the first shape of the first piece of electroactive material is that of a sheet curved in an arc with a first radius and the third shape of the first piece of electroactive material is that of the sheet curved in an arc with a second radius smaller than the first radius.

24. The method of claim 21, wherein the first voltage, the first signal, and the second voltage are applied at approximately the same time.

22. A method, comprising:

applying a first voltage to a first piece of electroactive material in an inlet valve to cause the first piece of electroactive material to take a first shape that at least partially restricts fluid flow through the inlet valve;

applying a first signal to a pump with an inlet connected to the inlet valve to cause the pump to expel fluid from the pump, the first piece of electroactive material having the first shape during at least some of a time that the pump expels fluid from the pump;

applying a second voltage to a second piece of electroactive material in an outlet valve connected to an outlet of the pump to cause the second piece of electroactive material to take a second shape that does not substantially restrict fluid flow through the inlet valve, the second piece of electroactive material having the second shape during at least some of the time that the pump expels fluid from the pump;

applying a third voltage to the first piece of electroactive material in the inlet valve to cause the first piece of electroactive material to take a third shape that does not substantially restrict fluid flow through the inlet valve;

applying a second signal to the pump with an inlet connected to the inlet valve to cause the pump to draw in fluid to the pump, the first piece of electroactive material having the third shape during at least some of a time that the pump draws in fluid to the pump;

and applying a fourth voltage to the second piece of electroactive material in the outlet valve to cause the second piece of electroactive material to take a fourth shape that at least partially restricts fluid flow through the outlet valve, the second piece of electroactive material having the fourth shape during at least some of the time that the pump draws in fluid to the pump.