Electroactive polymer devices

• US 6,545,384 B1
• Filed: 07/20/2000
• Issued: 04/08/2003
• Est. Priority Date: 02/07/1997
• Status: Expired due to Term

• Current Assignee: SRI International, Inc.
• Original Assignee: SRI International, Inc.
• Inventors: Pelrine, Ronald E., Kornbluh, Roy D.
• Primary Examiner(s): Dougherty, Thomas M.
• Application Number:
  US09/619,846
• Time in Patent Office: 992 Days
• Field of Search: 310/328, 310/330, 310/309, 310/800
• US Class Current: 310/309
• 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 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 35/045 using solenoids
• CPC Class Codes: F04B 43/043 Micropumps
• CPC Class Codes: F04B 43/14 having plate-like flexible members
• CPC Class Codes: F05C 2225/08 Thermoplastics
• CPC Class Codes: F25B 9/14 characterised by the cycle used, e.g. Stirling cycle
• CPC Class Codes: H02N 2/023 Inchworm motors
• CPC Class Codes: H04R 17/005 using a piezoelectric polymer
• CPC Class Codes: H04R 17/08 signals being recorded or played back by vibration of a stylus in two orthogonal directions simultaneously
• 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: H04R 2499/13 Acoustic transducers and sound field adaptation in vehicles
• CPC Class Codes: H04R 5/02 Spatial or constructional arrangements of loudspeakers
• CPC Class Codes: H10N 30/2042 Cantilevers, i.e. having one fixed end
• CPC Class Codes: H10N 30/206 using only longitudinal or thickness displacement, e.g. d33 or d31 type devices
• CPC Class Codes: H10N 30/30 with mechanical input and electrical output, e.g. functioning as generators or sensors
• CPC Class Codes: H10N 30/857 Macromolecular compositions
• CPC Class Codes: Y10S 310/80 Piezoelectric polymers, e.g. PVDF
• CPC Class Codes: Y10S 977/742 : Carbon nanotubes, CNTs
• CPC Class Codes: Y10S 977/788 : Of specified organic or carbon-based composition

Abstract

The present invention relates to transducers, their use and fabrication. The transducers convert between mechanical and electrical energy. Some transducers of the present invention include a pre-strained polymer. The pre-strain improves the conversion between electrical and mechanical energy. The present invention also relates to devices including an electroactive polymer to convert between electrical and mechanical energy. The present invention further relates to compliant electrodes that conform to the shape of a polymer included in a transducer. The present invention provides methods for fabricating electromechanical devices including one or more electroactive polymers.

Claims

1. A device for converting between electrical energy and mechanical energy, the device comprising:

at least one transducer, each transducer comprising;

at least two electrodes, and

a polymer arranged in a manner which causes a portion of the polymer to deflect in response to a change in electric field and/or arranged in a manner which causes a change in electric field in response to deflection of the polymer, wherein the polymer has an elastic modulus at most about 100 MPa without electrical energy applied thereto; and

at least one flexure coupled to a second portion of the polymer, the flexure improving conversion between electrical energy and mechanical energy.

2. The device of claim 1 further comprising a first stiff member attached to a third portion of the polymer and a second stiff member attached to a fourth portion of the polymer.

3. The device of claim 2 wherein the first and second stiff members are used to mechanically couple the device to a second device for converting between electrical energy and mechanical energy.

4. The device of claim 3 wherein the device is included in one of an actuator, a generator or a sensor.

5. The device of claim 1 wherein the polymer comprises pre-strain.

6. The device of claim 5 wherein the polymer comprises pre-strain in a second direction greater than pre-strain in a first direction.

7. The device of claim 1 wherein the flexure couples polymer deflection in a third direction into deflection in a fourth direction.

8. The device of claim 1 wherein the device is included in one of a robot, a motor or a toy.

9. The device of claim 1 wherein the transducer is stretched before the change in electric field.

10. The device of claim 9 wherein the at least two electrodes apply a voltage that produces a pressure in the polymer less than the elastic restoring stresses resulting from the stretch.

11. A device for converting between electrical energy and mechanical energy in a first direction, the device comprising:

at least one transducer, each transducer comprising;

at least two electrodes, and

a polymer arranged in a manner which causes a first portion of the polymer to deflect in the first direction in response to a change in electric field and/or arranged in a manner which causes a change in electric field in response to deflection of the polymer in the first direction; and

a pair of flexures coupled to opposing sides of the polymer, the pair of flexures improving conversion between electrical energy and mechanical energy in the first direction.

12. The device of claim 11 wherein the polymer comprises pre-strain.

13. The device of claim 11 wherein the pair of flexures couples polymer deflection in a second direction into displacement in the first direction.

14. The transducer of claim 11 wherein the transducer is included in one of a robot, a motor or a toy.

15. The device of claim 11 wherein the device is included in one of an actuator, a generator and a sensor.

16. A device for converting between electrical energy and mechanical energy, the device comprising:

at least one transducer, each transducer comprising;

at least two electrodes, and

a polymer arranged in a manner which causes a portion of the polymer to deflect in response to a change in electric field and/or arranged in a manner which causes a change in electric field in response to deflection of the polymer, wherein the polymer has an elastic modulus at most about 100 MPa without electrical energy applied thereto; and

a frame attached to a second portion of the polymer, the frame comprising at least one non-circular aperture.

17. The device of claim 16 wherein the non-circular aperture is a slot.

18. The device of claim 16 further comprising a bias pressure added to a first side of the polymer.

19. The device of claim 18 wherein the bias pressure is provided by a swelling agent.

20. The device of claim 16 wherein the device is included in one of an actuator, a generator or a sensor.

21. A device for converting between electrical energy and mechanical energy, the device comprising:

at least one transducer, each transducer comprising;

at least two electrodes, and

a polymer arranged in a manner which causes a portion of the polymer to deflect in response to a change in electric field and/or arranged in a manner which causes a change in electric field in response to deflection of the polymer, wherein the polymer has an elastic modulus at most about 100 MPa without electrical energy applied thereto; and

at least one flexure coupled to a second portion of the polymer, wherein deflection of the at least one flexure during deflection of the polymer improves conversion between electrical energy and mechanical energy.

22. The device of claim 21 further comprising a first stiff member attached to a third portion of the polymer and a second stiff member attached to a fourth portion of the polymer.

23. The device of claim 22 wherein the first and second stiff members are used to mechanically couple the device to a second device for converting between electrical energy and mechanical energy.

24. The device of claim 21 wherein the polymer comprises pre-strain.

25. The device of claim 24 wherein the polymer comprises pre-strain in a second direction greater than pre-strain in a first direction.

26. The device of claim 21 wherein the device is included in one of a robot, a motor or a toy.

27. A device for converting between electrical energy and mechanical energy, the device comprising:

at least one transducer, each transducer comprising;

at least two electrodes, and

a polymer arranged in a manner which causes a portion of the polymer to deflect in response to a change in electric field and/or arranged in a manner which causes a change in electric field in response to deflection of the polymer; and

a frame perimetrically disposed about a planar surface of the polymer and including a set of joints and a set of members, each of the members attached to a different perimetric portion of the polymer, and each joint allowing motion between two members coupled to the joint.

28. The device of claim 27 wherein the frame comprises six joints and six rigid members.

29. The device of claim 27 wherein the two members coupled to a joint have a different length.

30. The device of claim 27 wherein the frame improves conversion between electrical energy and mechanical energy for the polymer.

31. The device of claim 30 wherein the frame improves conversion between electrical energy and mechanical energy for the polymer during deflection of the polymer.

32. The device of claim 27 wherein the polymer comprises pre-strain.

33. The device of claim 32 wherein the polymer comprises pre-strain in a second direction greater than pre-strain in a first direction.