Source: http://www.google.com/patents/US20060113878?dq=6,928,433
Timestamp: 2015-11-28 19:42:44
Document Index: 235264024

Matched Legal Cases: ['Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60']

Patent US20060113878 - Electroactive polymers - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsThe 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...http://www.google.com/patents/US20060113878?utm_source=gb-gplus-sharePatent US20060113878 - Electroactive polymersAdvanced Patent SearchPublication numberUS20060113878 A1Publication typeApplicationApplication numberUS 11/335,805Publication dateJun 1, 2006Filing dateJan 18, 2006Priority dateJul 20, 1999Also published asUS6812624, US7049732, US7199501, US7224106, US7259503, US7468575, US7923064, US8508109, US20040263028, US20060113880, US20060238079, US20080136052, US20080191585, US20110154641, US20110155307Publication number11335805, 335805, US 2006/0113878 A1, US 2006/113878 A1, US 20060113878 A1, US 20060113878A1, US 2006113878 A1, US 2006113878A1, US-A1-20060113878, US-A1-2006113878, US2006/0113878A1, US2006/113878A1, US20060113878 A1, US20060113878A1, US2006113878 A1, US2006113878A1InventorsQibing Pei, Ronald Pelrine, Roy KornbluhOriginal AssigneeSri InternationalExport CitationBiBTeX, EndNote, RefManPatent Citations (55), Referenced by (69), Classifications (47), Legal Events (3) External Links: USPTO, USPTO Assignment, EspacenetElectroactive polymers
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority under U.S.C. �120 from co-pending U.S. patent application Ser. No. 10/893,730, filed Jul. 16, 2004 and entitled, “ELECTROACTIVE POLYMERS”, which is incorporated herein for all purposes and which claims priority from U.S. Pat. No. 6,812,624 B1, which claimed priority under 35 U.S.C. �119(e) from co-pending U.S. Provisional Patent Application No. 60/144,556 filed Jul. 20, 1999, naming R. E. Pelrine et al. as inventors, and titled “High-speed Electrically Actuated Polymers and Method of Use”, which is incorporated by reference herein for all purposes; it also claims priority under 35 U.S.C. �119(e) from co-pending U.S. Provisional Patent Application No. 60/153,329 filed Sep. 10, 1999, naming R. E. Pelrine et al. as inventors, and titled “Electrostrictive Polymers As Microactuators”, which is incorporated by reference herein for all purposes; it also claims priority under 35 U.S.C. �119(e) from co-pending U.S. Provisional Patent Application No. 60/161,325 filed Oct. 25, 1999, naming R. E. Pelrine et al. as inventors, and titled “Artificial Muscle Microactuators”, which is incorporated by reference herein for all purposes; it also claims priority under 35 U.S.C. �119(e) from co-pending U.S. Provisional Patent Application No. 60/181,404 filed Feb. 9, 2000, naming R. D. Kombluh et al. as inventors, and titled “Field Actuated Elastomeric Polymers”, which is incorporated by reference herein for all purposes; it also claims priority under 35 U.S.C. � 19(e) from co-pending U.S. Provisional Patent Application No. 60/187,809 filed Mar. 8, 2000, naming R. E. Pelrine et al. as inventors, and titled “Polymer Actuators and Materials”, which is incorporated by reference herein for all purposes; and it also claims priority under 35 U.S.C. �119(e) from co-pending U.S. Provisional Patent Application No. 60/192,237 filed Mar. 27, 2000, naming R. D. Kombluh et al. as inventors, and titled “Polymer Actuators and Materials II”, which is incorporated by reference herein for all purposes; it also claims priority under 35 U.S.C. � 119(e) from co-pending U.S. Provisional Patent Application No. 60/184,217 filed Feb. 23, 2000, naming R. E. Pelrine et al. as inventors, and titled “Electroelastomers and their use for Power Generation”, which is incorporated by reference herein for all purposes. This application cross references co-pending U.S. patent application entitled “Elastomeric Dielectric Polymer Film Sonic Actuator” naming R. E. Pelrine et al. as inventors, filed on Jul. 19, 1999 (U.S. application Ser. No. 09/356,801), which claims priority from PCT/US98/02311 filed Feb. 2, 1998, which claims priority from U.S. Provisional Application No. 60/037,400 filed Feb. 7, 1997, all of which are incorporated by reference herein. [0002] This invention is related to U.S. patent application Ser. No. 09/619,848, filed on Jul. 20, 2000, naming R. Pelrine et al. as inventors. That application is incorporated herein by reference in its entirety and for all purposes.
BACKGROUND OF THE INVENTION [0004] The present invention relates generally to electroactive polymers that convert between electrical energy and mechanical energy. More particularly, the present invention relates to polymers and their use as generators, sensors, in actuators and various applications. The present invention also relates to additives added to a polymer, laminates comprising a transducer and methods of fabricating transducer. [0005] In many applications, it is desirable to convert between electrical energy and mechanical energy. Exemplary applications requiring translation from electrical to mechanical energy include robotics, pumps, speakers, general automation, disk drives and prosthetic devices. These applications include one or more actuators that convert electrical energy into mechanical work—on a macroscopic or microscopic level. Common electric actuator technologies, such as electromagnetic motors and solenoids, are not suitable for many of these applications, e.g., when the required device size is small (e.g., micro or mesoscale machines). Exemplary applications requiring translation from mechanical to electrical energy include mechanical property sensors and heel strike generators. These applications include one or more transducers that convert mechanical energy into electrical energy. Common electric generator technologies, such as electromagnetic generators, are also not suitable for many of these applications, e.g., when the required device size is small (e.g., in a person's shoe). These technologies are also not ideal when a large number of devices must be integrated into a single structure or under various performance conditions such as when high power density output is required at relatively low frequencies. [0006] Several ‘smart materials’ have been used to convert between electrical and mechanical energy with limited success. These smart materials include piezoelectric ceramics, shape memory alloys and magnetostrictive materials. However, each smart material has a number of limitations that prevent its broad usage. Certain piezoelectric ceramics, such as lead zirconium titanate (PZT), have been used to convert electrical to mechanical energy. While having suitable efficiency for a few applications, these piezoelectric ceramics are typically limited to a strain below about 1.6 percent and are often not suitable for applications requiring greater strains than this. In addition, the high density of these materials often eliminates them from applications requiring low weight. Irradiated polyvinylidene difluoride (PVDF) is an electroactive polymer reported to have a strain of up to 4 percent when converting from electrical to mechanical energy. Similar to the piezoelectric ceramics, the PVDF is often not suitable for applications requiring strains greater than 4 percent. Shape memory alloys, such as nitinol, are capable of large strains and force outputs. These shape memory alloys have been limited from broad use by unacceptable energy efficiency, poor response time and prohibitive cost. [0007] In addition to the performance limitations of piezoelectric ceramics and irradiated PVDF, their fabrication often presents a barrier to acceptability. Single crystal piezoelectric ceramics must be grown at high temperatures coupled with a very slow cooling down process. Irradiated PVDF must be exposed to an electron beam for processing. Both these processes are expensive and complex and may limit acceptability of these materials. [0008] In view of the foregoing, alternative devices that convert between electrical and mechanical energy would be desirable. SUMMARY OF THE INVENTION [0009] In one aspect, the present invention relates to polymers that convert between electrical and 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. Similarly, when the polymer deflects, an electric field is produced in the polymer. This electric field may be used to produce electrical energy. Some polymers of the present invention include additives that improve conversion between electrical and mechanical energy. Other polymers of the present invention include laminate layers that improve conversion between electrical and mechanical energy. [0010] Some polymers of the present invention are pre-strained. The pre-strain improves the mechanical response of an electroactive polymer relative to a non-strained polymer. The pre-strain may vary in different directions of a polymer to vary response of the polymer to the applied voltage. [0011] In one aspect, the present invention relates to generators and actuators comprising an electroactive polymer and mechanical coupling to convert between mechanical and electrical energy. Several generators and actuators include structures that improve the performance of an electroactive polymer. [0012] In another aspect, the present invention relates to compliant electrodes that conform to the changing shape of a polymer. Many of the electrodes are capable of maintaining electrical communication at the high deflections encountered with pre-strained polymers of the present invention. In some embodiments, electrode compliance may vary with direction. [0013] In yet another aspect, the present invention provides methods for fabricating electromechanical devices comprising one or more electroactive polymers. Additives that improve conversion between electrical and mechanical energy may be added during fabrication. Polymers of the present invention may be made by casting, dipping, spin coating, spraying or other known processes for fabrication of thin polymer layers. [0014] In still another aspect, the invention relates to a generator for converting mechanical energy to electrical energy. The generator comprising at least two electrodes. The transducer also comprising a polymer arranged in a manner which causes a change in electric field in response to a deflection applied to a first portion of the polymer, wherein a second portion of the polymer is elastically pre-strained. [0015] In another aspect, the invention relates to a generator for converting mechanical energy to electrical energy. The generator comprising at least two electrodes. The transducer also comprising a polymer having a substantially constant thickness and an area orthogonal to the thickness, the polymer arranged in a manner which causes a change in electric field in response to a net area decrease of the polymer for the area orthogonal to the thickness. [0016] In still another aspect, the invention relates to a generator for converting from electrical energy to mechanical energy. The generator comprising at least one transducer, each transducer comprising at least two electrodes and a polymer arranged in a manner which causes a change in electric field in response to a deflection applied to a first portion of the polymer. The generator also comprising a frame attached to a second portion of the polymer, the frame comprising at least one aperture, wherein the first portion of the polymer is arranged in a manner which causes a change in electric field in response to a deflection applied to a third portion of the polymer. [0017] In yet another aspect, the invention relates to a generator for converting mechanical energy in a first direction into electrical energy. The generator comprising at least one transducer, each transducer comprising at least two electrodes and a polymer arranged in a manner which causes a change in electric field in response to a deflection in the first direction. The generator also comprising a flexible frame coupled to the polymer, the frame providing improved conversion from mechanical to electrical energy for the at least one transducer. [0018] In another aspect, the invention relates to a generator for converting mechanical energy in a first direction into electrical energy. The generator comprising at least one transducer, each transducer comprising at least two electrodes and a polymer arranged in a manner which causes a change in electric field in response to a deflection in the first direction. The generator also comprising at least one stiff member coupled to the at least one transducer, the at least one stiff member substantially preventing displacement in a second direction. [0019] In still another aspect, the invention relates to a transducer for converting between mechanical and electrical energy. The 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 includes an additive. [0020] In yet another aspect, the invention relates to a transducer for converting between mechanical and electrical energy. The 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 comprises a monoethylenically unsaturated monomer homopolymerizable to form a polymer having a glass transition temperature less than about 0 degrees Celsius. [0021] In another aspect, the invention relates to a transducer for converting between mechanical and electrical energy. The 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 comprises a thermoplastic elastomer. [0022] In still another aspect, the invention relates to a transducer for converting between mechanical and electrical energy. The 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 comprises silicone and acrylic moieties. [0023] In yet another aspect, the invention relates to a transducer for converting between mechanical and electrical energy. The 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 to change in electric field in response to deflection. The transducer also comprising a layer laminated to at least a portion of one of the polymer and the at least two electrodes, and mechanically coupled to the polymer and/or one of the at least