Electrolytic actuators: Alternative, high-performance, material-based devices
- Molecular Materials Research Center, Beckman Institute M/C 139-74, California Institute of Technology, Pasadena, CA 91125
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Communicated by Fred C. Anson, California Institute of Technology, Pasadena, CA (received for review February 11, 2002)
Abstract
The emerging field of materials-based actuation continues to be the focus of considerable research because of its inherent scalability and its promise to drive micromechanical devices that cannot be realized with conventional mechanical actuator strategies. The electrolytic phase transformation actuator offers a new broad-spectrum solution to the problem of direct conversion of electrical to mechanical energy. Strains of 136,000% and unoptimized work cycle efficiencies near 50% are demonstrated in a prototype device. Conceivably capable of generating stress beyond 200 MPa, this new approach promises performance orders of magnitude beyond other novel actuation strategies.
Footnotes
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↵ * To whom reprint requests should be sent at the present address: Department of Chemistry, University of Manitoba, Winnipeg, MB, Canada R3T 2N2. E-mail: michael_freund{at}umanitoba.ca.
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↵ ¶ Devices using potential-driven differential surface tension, or “continuous electrowetting,” to drive small plugs of fluid linearly along a capillary have been demonstrated (25). Since this effect stems entirely from induced changes in surface free energy and does not inflict any sort of physical change in the medium, it is not per se a materials-based actuation strategy.
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↵ † Molter, T., U.S. Department of Energy 1999 Review Conference on Fuel Cell Technology, August 3–5, 1999, Chicago.
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↵ ‡ This refers to the cross-sectional area of the fuel cell cathode, and hence of the whole cell. Since O2 reduction is the limiting process in a H2/O2 PEM fuel cell, the performance predictions that follow are also based on the area of exposed cathode.
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↵ § An expansion of 0.1 ml in a gas headspace of 4 ml would require a temperature increase of 7°C.
- Abbreviations:
- EPT,
- electrolytic phase transformation;
- PEM,
- proton exchange membrane
- Copyright © 2002, The National Academy of Sciences
