Monolithic electroactive polymers

• US 7,911,115 B2
• Filed: 07/12/2007
• Issued: 03/22/2011
• Est. Priority Date: 07/20/1999
• Status: Expired due to Term

• Current Assignee: SRI International, Inc.
• Original Assignee: SRI International, Inc.
• Inventors: Pei, Qibing, Kornbluh, Roy D., Eckerle, Joseph S., Pelrine, Ronald E.
• Primary Examiner(s): Dougherty; Thomas M
• Application Number:
  US11/777,036
• Publication Number:
  US 20100026143A1
• Time in Patent Office: 1,349 Days
• Field of Search: 310/317, 310/328, 310/330, 310/366, 310/800
• US Class Current: 310/328
• 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 present invention relates to polymers, transducers and devices that convert between electrical and mechanical energy. When a voltage is applied to electrodes contacting an electroactive polymer, the polymer deflects. This deflection may be used to do mechanical work. Similarly, when the electroactive polymer deflects, an electric field is produced in the polymer. This electric field may be used to produce electrical energy. An active area is a portion of a polymer having sufficient electrostatic force to enable deflection of the portion and/or sufficient deflection to enable a change in electrostatic force. The present invention relates to transducers and devices including multiple active areas. The invention also relates to methods for actuating one or more active areas.

Claims

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

a first active area having at least two first active area electrodes and a first portion of an electroactive polymer arranged in a manner which causes the first portion to deflect in response to a change in electric field provided by the at least two first active area electrodes and/or arranged in a manner which causes a change in electric field in response to deflection of the first portion; and

a second active area having at least two second active area electrodes and a second portion of the electroactive polymer arranged in a manner which causes the second portion to deflect in response to a change in electric field provided by the at least two second active area electrodes and/or arranged in a manner which causes a change in electric field in response to deflection of the second portion,

wherein the electroactive polymer has an elastic modulus below 100 MPa.

2. The transducer of claim 1 wherein the first and second active areas are arranged such that deflection of the first portion includes a direction of elastic contraction that is at least partially linearly aligned with a direction of elastic expansion for the second portion.

3. The transducer of claim 1 wherein the first and second active areas are symmetrically arranged.

4. The transducer of claim 3 wherein the at least two first active area electrodes and the at least two second active area electrodes are arranged radially around a central point.

5. The transducer of claim 1 wherein electrical communication between the at least two first active area electrodes and the first portion is independent from electrical communication between the at least two second active area electrodes and the second portion.

6. The transducer of claim 1 wherein one of the at least two first active area electrodes is electrically coupled to one of the at least two second active area electrodes.

7. The transducer of claim 6 wherein the one of the at least two first active area electrodes electrically coupled to the one of the at least two second active area electrodes is a common electrode.

8. The transducer of claim 1 wherein the electroactive polymer includes an additive.

9. The transducer of claim 8 wherein the additive improves at least one of polymer dielectric breakdown strength, maximum linear strain, dielectric constant, elastic modulus, response time, and actuation voltage.

10. The transducer of claim 1 wherein the electroactive polymer is substantially planar.

11. A method for using an electroactive polymer comprising a first active area and a second active area, the first active area having at least two first active area electrodes and a first portion of the electroactive polymer, the second active area having at least two second active area electrodes and a second portion of the electroactive polymer, the method comprising:

a) providing a change in electric field to the at least two first active area electrodes; and

b) providing a change in electric field to the at least two second active area electrodes,

wherein the electroactive polymer has an elastic modulus below 100 MPa.

12. The method of claim 11 further comprising mechanically deflecting the first portion before providing the change in electric field to the at least two first active area electrodes.

13. The method of claim 12 wherein the change in electric field provided to the at least two first active area electrodes is less than the electric field needed to further deflect the first portion.

14. The method of claim 13 further comprising mechanically deflecting the first portion after the change in electric field has been provided, wherein the mechanical deflection after the change in electric field has been provided increases the electrical field between the at least two first active area electrodes.

15. The method of claim 11 wherein the change in electric field provided to the at least two first active area electrodes deflects the first portion.

16. The method of claim 11 wherein the change in electric field provided to the at least two second active area electrodes deflects the second portion.

17. The method of claim 16 wherein the second portion is deflected such that elastic energy of the first portion assists a deflection of the second portion.

18. The method of claim 17 wherein deflection of the second portion begins when the first portion is at a peak expansion.

19. The method of claim 11 wherein the change in electric field provided to the at least two first active area electrodes terminates before the change in electric field provided to the at least two second active area electrodes begins.

20. The method of claim 11 wherein the electroactive polymer includes an additive.