Electroactive polymer fabrication

• US 6,543,110 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., Oh, Seajin, Joseph, Jose P.
• Primary Examiner(s): Walczak, David J.
• Application Number:
  US09/619,845
• Time in Patent Office: 992 Days
• Field of Search: 295/94, 29/253.5, 295/95, 295/921, 261/291, 310/800, 425/383
• US Class Current: 29/25.35
• 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: 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 30/098 Forming organic materials
• CPC Class Codes: H10N 30/206 using only longitudinal or thickness displacement, e.g. d33 or d31 type devices
• CPC Class Codes: H10N 30/886 Additional mechanical prestressing means, e.g. springs
• CPC Class Codes: Y10S 977/742 Carbon nanotubes, CNTs
• CPC Class Codes: Y10S 977/788 Of specified organic or carbon-based composition
• CPC Class Codes: Y10S 977/842 for carbon nanotubes or fullerenes
• CPC Class Codes: Y10T 29/42 Piezoelectric device making
• CPC Class Codes: Y10T 29/49005 Acoustic transducer
• CPC Class Codes: Y10T 29/49007 : Indicating transducer

Abstract

Pre-strained electroactive polymers are described that improve conversion from electrical to mechanical energy. When a voltage is applied to electrodes contacting a pre-strained polymer, the polymer deflects. This deflection may be used to do mechanical work. The pre-strain improves the mechanical response of an electroactive polymer. Also described herein are actuators that include an electroactive polymer and mechanical coupling to convert deflection of the polymer into mechanical work. Further described are compliant electrodes that conform to the shape of a polymer. Methods for fabricating electromechanical devices including one or more electroactive polymers are also described.

Claims

1. A method of fabricating a transducer comprising a pre-strained polymer and one or more electrodes, the method comprising:

pre-straining a first portion of a polymer to form the pre-strained polymer, wherein the polymer has an elastic modulus below 100 MPa;

fixing a second portion of the pre-strained polymer to a solid member; and

forming the one or more electrodes on the pre-strained polymer.

2. The method of claim 1 wherein the pre-strained polymer is elastically pre-strained.

3. The method of claim 1 wherein the polymer is one of a commercially available silicone elastomer, polyurethane, PVDF copolymer or adhesive elastomer.

4. The method of claim 1 further comprising spin coating a polymer mixture to produce the polymer.

5. The method of claim 4 further comprising releasing the polymer from a rigid substrate used in the spin coating.

6. The method of claim 1 further comprising texturing a surface of the polymer.

7. The method of claim 6 wherein the texturing comprises attaching a layer of stiff material to the polymer and relaxing the polymer and the stiff material.

8. The method of claim 1 wherein the forming one or more electrodes comprises spraying the one or more electrodes onto the pre-strained polymer using a mask.

9. The method of claim 1 wherein one or more electrodes are patterned photolithographically on the pre-strained polymer.

10. The method of claim 1 further comprising attaching the solid member to a portion of a second pre-strained polymer.

11. The method of claim 1 further comprising assembling the polymer and the one or more electrodes in an actuator.

12. The method of claim 1 wherein pre-straining the polymer comprises attaching a structural elastomer to the pre-strained polymer.

13. The method of claim 12 wherein the structural elastomer is patterned.

14. The method of claim 1 wherein pre-straining the polymer comprises attaching one or more stiffeners.

15. The method of claim 1 wherein the polymer is pre-strained by a factor in the range of about 1.5 times to 50 times the original area.

23. The method of claim 1 wherein the polymer has a maximum actuation pressure in response to electricity provided by the one or more electrodes between about 0.05 MPa and about 10 MPa.

24. The method of claim 1 wherein the polymer has a maximum actuation pressure in response to electricity provided by the one or more electrodes between about 0.3 MPa and about 3 MPa.

16. A method of fabricating a transducer comprising multiple pre-strained polymers, the method comprising:

(a) pre-straining a first polymer to form a first pre-strained polymer;

(b) forming one or more electrodes on the first pre-strained polymer;

(c) pre-straining a second polymer to form a second pre-strained polymer;

(d) forming one or more electrodes on the second pre-strained polymer; and

(e) coupling the first pre-strained polymer to the second pre-strained polymer.

17. The method of claim 16 wherein pre-straining comprises stretching the polymer and fixing it to a solid member.

18. The method of claim 16 further comprising spin coating a polymer mixture to produce the polymer.

19. The method of claim 18 further comprising releasing the polymer from a rigid substrate used in the spin coating.

20. The method of claim 19 wherein releasing the pre-strained polymer from the rigid substrate comprises one of an etchant or peeling the polymer from the rigid frame.

21. The method of claim 16 further comprising repeating (c) to (e).

22. The method of claim 16 wherein coupling the first pre-strained polymer to the second pre-strained polymer comprises attaching the first pre-strained polymer to the second pre-strained polymer.