Electroactive polymers

• US 20060113878A1
• Filed: 01/18/2006
• Published: 06/01/2006
• Est. Priority Date: 07/20/1999
• Status: Active Grant

• Current Assignee: SRI International, Inc.
• Original Assignee: SRI International, Inc.
• Inventors: Kornbluh, Roy D., Pelrine, Ronald E., Pei, Qibing
• Granted Patent: US 7,259,503 B2
• Time in Patent Office: Days
• US Class Current: 310/363
• 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: F05C 2225/08 Thermoplastics
• CPC Class Codes: F25B 9/14 characterised by the cycle used, e.g. Stirling cycle
• CPC Class Codes: H01G 5/16 using variation of distance between electrodes
• CPC Class Codes: H02N 2/023 Inchworm 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: H10N 30/098 Forming organic materials
• 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 30/308 Membrane type
• CPC Class Codes: H10N 30/857 Macromolecular compositions
• CPC Class Codes: H10N 30/87 Electrodes or interconnections, e.g. leads or terminals
• 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: Y10T 29/49826 : Assembling or joining

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. 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 material having an aspect ratio greater than about 2 and an electrode thickness less than about 4 micrometers.

2. The electrode of claim 1 wherein the electrode thickness is less than about 2 micrometers when applied to the electroactive polymer.

3. The electrode of claim 1 wherein the conductive material comprises carbon fibrils.

4. The electrode of claim 1 wherein the conductive material comprises carbon nanotubes.

5. The electrode of claim 1 wherein the aspect ratio of the conductive material is greater than about 4.

6. The electrode of claim 1 further including a polymer binder that polymer binder that increases adhesion between the electrode and the electroactive polymer.

7. The electrode of claim 1 wherein the compliant electrode includes a solvent before application onto the polymer and permits spray coating onto the polymer.

8. The electrode of claim 7 wherein the compliant electrode permits spray coating onto a portion of the electroactive polymer to define an active area according to a geometry of the spray coated electrode.

9. The electrode of claim 1 wherein the compliant electrode is capable of a maximum linear strain of at least about 50 percent.

10. 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 material comprising carbon fibrils or carbon nanotubes and wherein the compliant portion is capable of deflection with a maximum linear strain of at least about 40 percent.

11. The electrode of claim 10 further including a polymer binder that polymer binder that increases adhesion between the electrode and the electroactive polymer.

12. The electrode of claim 10 wherein the electroactive polymer is an acrylic polymer.

13. The electrode of claim 10 wherein the electroactive polymer has an elastic modulus at most about 100 MPa.

14. The electrode of claim 10 wherein the compliant electrode is capable of a maximum linear strain of at least about 50 percent.

15. 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 one or more regions of low conductivity comprise a charge distribution layer that has a conductance greater than the electroactive polymer.

16. The electrode of claim 15 wherein either the regions of high conductivity or the regions of low conductivity or both comprise a set of patterned traces.

17. The electrode of claim 16 wherein the set of patterned traces comprise a metal material.

18. The electrode of claim 16 wherein the set of patterned traces are configured to allow expansion and contraction of the electroactive polymer in multiple directions.

19. The electrode of claim 16 wherein the set of patterned traces form an active area according to the geometry of the electrode.