Electroactive polymer devices for moving fluid

• US 20040008853A1
• Filed: 03/18/2003
• Published: 01/15/2004
• Est. Priority Date: 07/20/1999
• Status: Active Grant

• Current Assignee: SRI International, Inc.
• Original Assignee: SRI International, Inc.
• Inventors: Eckerle, Joseph S., Heim, Jonathan R., Pelrine, Ronald E., Pei, Qibing, Stanford, Scott E., Kornbluh, Roy David, Heydt, Richard
• Granted Patent: US 7,064,472 B2
• Time in Patent Office: Days
• US Class Current: 381/191
• 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 for performing thermodynamic work on a fluid, the device comprising:

one or more transducers, each transducer comprising at least two electrodes and an electroactive polymer in electrical communication with the at least two electrodes wherein a portion of the electroactive polymer is arranged to deflect from a first position to a second position in response to a change in electric field;

at least one surface in contact with a fluid and operatively coupled to the one or more transducers wherein the deflection of the portion of the electroactive polymer causes the thermodynamic work to be imparted to the fluid and wherein the thermodynamic work is transmitted to the fluid via the one surface.

2. The device of claim 1, wherein the device is selected from the group consisting of a pump, a compressor, a hydraulic actuator, a fan and combinations thereof.

3. The device of claim 1, wherein the deflection of the portion of the electroactive polymer changes the one surface from a first shape to a second shape.

4. The device of claim 1, wherein the one surface is operatively coupled to the one or more transducers via a mechanical linkage.

5. The device of claim 1, wherein the one surface includes the portion of the electroactive polymer.

6. The device of claim 5, wherein the one surface expands to form one of a balloon-like shape, a hemispherical shape, a cylinder shape, or a half-cylinder shape.

7. The device of claim 1, wherein the fluid is one of compressible, incompressible or combinations thereof.

8. The device of claim 1, wherein the fluid is one of a Newtonian or a non-Newtonian fluid.

9. The device of claim 1, wherein the fluid is selected from the group consisting of a gas, a plasma, a liquid, a mixture of two or more immiscible liquids, a supercritical fluid, a slurry, a suspension, and combinations thereof.

10. The device of claim 1, wherein the deflection of the one portion of the electroactive polymer generates one of rotational motion, linear motion, vibrational motion or combinations thereof for the one surface.

11. The device of claim 1, further comprising:

a chamber for receiving the fluid wherein a bounding surface of the chamber includes the one surface.

12. The device of claim 11, wherein the chamber is formed from one of a bladder or a bellows.

13. The device of claim 12, wherein the deflection of the portion of the electroactive polymer squeezes the bladder or bellows to reduce a volume of the bladder or the bellows.

14. The device of claim 12, wherein the deflection of the portion of the electroactive polymer stretches the bladder or bellows to increase a volume of the bladder or the bellows.

15. The device of claim 11, wherein the chamber is formed from a cylinder and a piston wherein the one surface is a portion of a piston head.

16. The device of claim 11, wherein the deflection of the portion of the electroactive polymer causes a change in a volume of the chamber.

17. The device of claim 16, wherein the change in the volume in the chamber compresses the fluid.

18. The device of claim 16, wherein the change in the volume in the chamber expands the fluid.

19. The device of claim 16, wherein the change in the volume in the chamber causes a thermodynamic phase change in at least a portion of the fluid.

20. The device of claim 16, wherein the change in volume in the chamber draws fluid into the chamber.

21. The device of claim 16, wherein the change in volume in the chamber expels fluid from the chamber.

22. The device of claim 1, further comprising a fan blade wherein the one surface is a portion of a surface of the fan blade.

23. The device of claim 22, wherein the deflection of the portion of the electroactive polymer causes the fan blade to rotate.

24. The device of claim 22, wherein the deflection of the portion of the electroactive causes a shape of the fan blade to change to alter an aerodynamic performance of the fan blade.

25. The device of claim 22, wherein the deflection of the portion of the electroactive polymer causes a pitch of the fan blade to change.

26. The device of claim 22, wherein the deflection of the portion of the electroactive polymer causes a change in one of an aeroelastic property or an aeroacoustic property of the fan blade.

27. The device of claim 22, wherein the fan blade is a component in a fan, a pump or a compressor.

28. The device of claim 1, wherein the thermodynamic work provides a driving force to move the fluid from a first location to a second location.

29. The device of claim 1, further comprising

one or more fluid conduits used to provide at least a portion of a flow path for allowing the fluid to travel through the device.

30. The device of claim 29, further comprising

one or more valves for controlling one of a flow rate, a flow direction and combinations thereof of the fluid through the flow path.

31. The device of claim 30, wherein the one or more valves is a check valve.

32. The device of claim 1, wherein the device is used in a thermal control system for controlling a temperature at one or more locations in a second device.

33. The device of claim 32, wherein the second device is a computer and one of the locations is proximate to a microprocessor for the computer.

34. The device of claim 32, wherein the fluid is for conducting heat energy from a first location to a second location in the second device.

35. The device of claim 34, wherein at least a portion of the fluid is in a liquid phase.

36. The device of claim 1, further comprising a heat exchanger for adding or for removing heat energy from the fluid.

37. The device of claim 36, wherein one or more portions of the electroactive polymer acts as the heat exchanger.

38. The device of claim 1, wherein the device is one of a pump or a compressor for a refrigeration system.

39. The device of claim 1, wherein the deflection of the portion of the polymer induces a wave like motion in the one surface and wherein the wave like motion imparts the thermodynamic work to the fluid.

40. The device of claim 1, further comprising:

a force return mechanism wherein the force return mechanism provides at least a portion of a force for returning the portion of the electroactive polymer from the second position to the first position.

41. The device of claim 40, wherein the force return mechanism is a spring.

42. The device of claim 1, further comprising a fluid conduit wherein the deflection of the portion of the electroactive polymer generates a peristaltic motion in the fluid conduit to move the fluid through the fluid conduit.

43. The device of claim 1, further comprising a fluid conduit wherein the deflection of the portion of electroactive polymer generates a wave-like motion in the fluid conduit to move fluid in the fluid conduit through the conduit.

44. The device of claim 1, wherein the one or more transducers are designed to operate like a flagella.

45. The device of claim 44, wherein a portion of the fluid conduit is comprised of an EPAM roll transducer.

46. The device of claim 1, further comprising:

a bias mechanism for biasing a direction of deflection of the portion of the electroactive polymer.

47. The device of claim 46, wherein the bias mechanism is one of a spring, a swelling agent, an insert or combinations thereof.

48. The device of claim 1, further comprising an output shaft designed to receive a hydraulic force generated from a pressure in the fluid.

49. The device of claim 48, wherein the deflection in the portion of the electroactive polymer causes the pressure in the fluid to increase and provide the hydraulic force for moving the output shaft.

50. The device of claim 1, wherein the device is a stage in one of a multi-stage pump or a multi-stage compressor.

51. The device of claim 1, wherein an acoustic signal generated by an operation of the device is above or below a human hearing range.

52. The device of claim 1, wherein an operating frequency at which the portion of the electroactive polymer deflects is above or below a human hearing range.

53. The device of claim 52, wherein the operating frequency is below 30 Hz.

54. The device of claim 1, further comprising a housing for enclosing the one or more transducers and the one surface.

55. The device of claim 54, wherein a flatness parameter defined as a height of the housing squared divided by a foot print area of the housing is substantially less than 1.

56. The device of claim 55, wherein the flatness parameter is less than about 0.1.

57. The device of claim 55, wherein the flatness parameter is less than about 0.05.

58. The device of claim 55, wherein the flatness parameter is less than about 0.01.

59. The device of claim 1, further comprising a clamp plate with a plurality of apertures wherein the electroactive polymer is an electroactive polymer film designed to deflect into the plurality of apertures.

60. The device of claim 59, further comprising a lower chamber designed to mount to the clamp plate and to secure the film between the clamp plate and the lower chamber.

61. The device of claim 60, wherein a pumping chamber for receiving the fluid is formed by a portion of a surface of the lower chamber and a portion of a surface of the film.

62. The device of claim 61, wherein the lower chamber further comprises one or more fluid conduits for conducting the fluid to the pumping chamber and for conducting the fluid away from the pumping chamber.

63. The device of claim 1, wherein the deflection of the portion electroactive polymer propels the device through the fluid.

64. The device of claim 1, wherein the device is used in a toy.

65. The device of claim 1, wherein the fluid is ink used in an inkjet printer.

66. The device of claim 1, wherein the deflection of the portion of the electroactive polymer further causes a change in a characteristic of the fluid that is transmitted to the fluid via the one surface.

67. The device of claim 66, wherein the characteristic of the fluid is selected from the group consisting of 1) a flow rate, 2) a flow direction, 3) a flow vorticity, 4) a flow momentum, 5) mixing, 6) flow turbulence, 7) fluid energy, 8) a fluid thermodynamic property, 9) a fluid rheological property.

68. The device of claim 1, further comprising a bellows spring wherein the bellows spring forms a part of a fluid conduit that provides a flow path that allows the fluid to flow through the bellows spring.

69. The device of claim 68, wherein the deflection of the portion of the electroactive polymer from the first position to the second position causes a diameter of the bellows spring to increase.

70. The device of claim 69, wherein a flow rate through the bellows spring is proportional to the diameter of the bellows spring.

71. The device of claim 1, further comprising one or more sensors connected to the device for measuring a property of the fluid.

72. The device of claim 71, wherein the property of the fluid is selected from the group consisting of a temperature, a pressure, a density, a viscosity, a thermal conductivity, a flow rate, and a concentration of a constituent of the fluid.

73. The device of claim 1, further comprising one or more sensors connected to the device for monitoring one or more of the deflection of the portion of the polymer, a charge on the portion of the polymer, and a voltage across the portion of the electroactive polymer.

74. The device of claim 1, further comprising a logic device for at least one of:

1) controlling operation of the transducer,

     2) monitoring one or more sensors,

     3) communicating with other devices, and

     4) combinations thereof.

75. The device of claim 1, further comprising conditioning electronics designed or configured to perform one or more of the following functions for the one or more transducers:

voltage step-up, voltage step-down and charge control.

76. The device of claim 1, wherein the electroactive polymer comprises a material selected from the group consisting of a silicone elastomer, an acrylic elastomer, a polyurethane, a copolymer comprising PVDF, and combinations thereof.

77. The device of claim 1, further comprising:

an insulation barrier designed or configured to protect the one surface from constituents of the fluid in contact with the one surface.

78. The device of claim 1, further comprising:

one or more support structures designed or configured to attach to the one or more transducers.

79. The device of claim 1, wherein the electroactive polymer is elastically pre-strained at the first position to improve a mechanical response of the electroactive polymer between the first position and second position.

80. The device of claim 1, wherein the electroactive polymer has an elastic modulus below about 100 MPa.

81. The device of claim 1, wherein the electroactive polymer has an elastic area strain of at least about 10 percent between the first position and the second position.

82. The device of claim 1, wherein the electroactive polymer comprises a multilayer structure.

83. The device of claim 82, wherein the multilayer structure comprises two or more layers of electroactive polymers.

84. The device of claim 1, wherein the device is a Micro-electro-mechanical System (MEMS) device.

85. The device of claim 55, wherein the MEMS device is fabricated on a silicon substrate.

86. The device of claim 1, wherein the device is one of a bellows bump, a centrifugal pump, a diaphragm pump, a rotary pump, a gear pump or an air-lift pump.

87. The device claim 1, wherein the device is one of an air compressor, a fuel pump, an oil pump, a water pump, a cooling fan, an exhaust gas re-circulation pump, a tire pump, a refrigeration pump or a windshield wiper fluid pump.

88. A medical device comprising claim 1.

89. The medical device of claim 88 wherein the medical device is for a host.

90. The medical device of claim 89, wherein the host is one of a human or an animal.

91. The medical device of claim 89, wherein the medical device is one of implantable inside the host, worn by the host or an extra-corporal device.

92. The medical device of claim 89, wherein the medical device is part of a thermal control system used to regulate a temperature of the host.

93. The medical of device of claim 88, wherein the medical device is one of a cardiac assist device, a pulmonary assist device, a dialysis device, a plasmaphoresis device, a blood pumping device, a drug delivery device, an IV device and a medical ventilator.

94. The medical device of claim 88, wherein the fluid is one of air, urine, blood, a pharmaceutical composition, blood plasma and a food mixture.

95. The device of claim 50, wherein a first stage is stacked on top of a second stage.

96. The device of claim 50, wherein a first stage is located inside of a second stage.

97. The device of claim 50, wherein a first stage is linearly aligned with a second stage.