Electroactive polymer electrodes

• US 6,376,971 B1
• Filed: 07/20/2000
• Issued: 04/23/2002
• 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., Pei, Qibing, Joseph, Jose P.
• Primary Examiner(s): Dougherty, Thomas M.
• Application Number:
  US09/619,843
• Time in Patent Office: 642 Days
• Field of Search: 310/363, 310/364
• US Class Current: 310/363
• 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 30/206 using only longitudinal or thickness displacement, e.g. d33 or d31 type devices
• CPC Class Codes: H10N 30/877 Conductive materials
• CPC Class Codes: H10N 30/878 the principal material being non-metallic, e.g. oxide or carbon based
• CPC Class Codes: Y10S 310/80 Piezoelectric polymers, e.g. PVDF
• CPC Class Codes: Y10S 977/742 Carbon nanotubes, CNTs
• CPC Class Codes: Y10S 977/753 with polymeric or organic binder
• CPC Class Codes: Y10S 977/788 Of specified organic or carbon-based composition
• CPC Class Codes: Y10S 977/809 Organic film on silicon
• CPC Class Codes: Y10S 977/842 : for carbon nanotubes or fullerenes
• CPC Class Codes: Y10S 977/899 : Electrolytic

Abstract

The present invention relates to electroactive polymers that are pre-strained to 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. The present invention also relates to actuators including an electroactive polymer and mechanical coupling to convert deflection of the polymer into mechanical work. The present invention further relates to compliant electrodes that conform to the shape of a polymer. The present invention provides methods for fabricating electromechanical devices including one or more electroactive polymers.

Claims

1. An electrode for use with an electroactive polymer, the electrode comprising:

a compliant portion in contact with the electroactive polymer, wherein the compliant portion comprises one or more regions of high conductivity and one or more regions of low conductivity, and wherein the compliant portion is capable of deflection with a maximum linear strain of at least about 50 percent.

2. The electrode of claim 1 wherein the regions of high conductivity include a set of metal traces.

3. The electrode of claim 2 wherein the metal traces form one or more specialized active regions.

7. The electrode of claim 1 wherein the compliant portion is capable of deflection with a maximum linear strain of at least about 100 percent.

8. The electrode of claim 1 wherein the one or more regions of high conductivity comprise patterned metal traces.

9. The electrode of claim 8 wherein the one or more regions of low conductivity comprises a charge distribution layer that has a conductance greater than the electroactive polymer and less than the conductance of the patterned metal traces.

10. The electrode of claim 8 wherein the patterned metal traces are offset from patterned metal traces included in a second electrode on an opposing side of the electroactive polymer.

11. The electrode of claim 8 wherein the patterned metal traces are configured to allow expansion and contraction of the electroactive polymer in multiple directions.

12. The electrode of claim 1 wherein the one or more regions of low conductivity has a surface resistivity in the range of about 10⁶ ohms to about 10¹¹ ohms.

4. An electrode for use with an electroactive polymer, the electrode comprising:

a compliant portion in contact with the electroactive polymer, wherein the electrode comprises a colloidal suspension, and wherein the compliant portion is capable of deflection with a maximum linear strain of at least about 50 percent.

13. The electrode of claim 4 wherein the electrode is patterned to form an active area according to the geometry of the electrode.

14. The electrode of claim 13 wherein the electrode is patterned by spraying the colloidal suspension onto the electroactive polymer.

15. The electrode of claim 4 wherein the colloidal suspension comprises one of graphite, silver and gold.

16. The electrode of claim 4 wherein the colloidal suspension comprises a silicone that improves adhesion between the electroactive polymer and the electrode.

17. The electrode of claim 4 wherein the colloidal suspension comprises a conductive grease.

18. The electrode of claim 17 wherein the colloidal suspension comprises a conductive silicone.

19. The electrode of claim 18 wherein the colloidal suspension is cured to form a conductive semi-solid.

5. An electrode for use with an electroactive polymer, the electrode comprising:

a compliant portion in contact with the electroactive polymer, wherein the electrode comprises a conductive grease, and wherein the compliant portion is capable of deflection with a maximum linear strain of at least about 50 percent.

20. The electrode of claim 5 wherein the conductive grease comprises carbon particles.

21. The electrode of claim 5 wherein the compliant portion is capable of deflection with a maximum linear strain of at least about 100 percent.

6. An electrode for use with an electroactive polymer, the electrode comprising:

a compliant portion in contact with the electroactive polymer, wherein the electrode comprises a mixture of ionically conductive materials, and wherein the compliant portion is capable of deflection with a maximum linear strain of at least about 50 percent.

22. The electrode of claim 6 wherein the mixture of ionically conductive materials comprises a water-based emulsion.