26 March 2014 Simple and strong: twisted silver painted nylon artificial muscle actuated by Joule heating
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Highly oriented nylon and polyethylene fibres shrink in length when heated and expand in diameter. By twisting and then coiling monofilaments of these materials to form helical springs, the anisotropic thermal expansion has recently been shown to enable tensile actuation of up to 49% upon heating. Joule heating, by passing a current through a conductive coating on the surface of the filament, is a convenient method of controlling actuation. In previously reported work this has been done using highly flexible carbon nanotube sheets or commercially available silver coated fibres. In this work silver paint is used as the Joule heating element at the surface of the muscle. Up to 29% linear actuation is observed with energy and power densities reaching 840 kJ m-3 (528 J kg-1) and 1.1 kW kg-1 (operating at 0.1 Hz, 4% strain, 1.4 kg load). This simple coating method is readily accessible and can be applied to any polymer filament. Effective use of this technique relies on uniform coating to avoid temperature gradients.
© (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Seyed M. Mirvakili, Seyed M. Mirvakili, Ali Rafie Ravandi, Ali Rafie Ravandi, Ian W Hunter, Ian W Hunter, Carter S. Haines, Carter S. Haines, Na Li, Na Li, Javad Foroughi, Javad Foroughi, Sina Naficy, Sina Naficy, Geoffrey M. Spinks, Geoffrey M. Spinks, Ray H. Baughman, Ray H. Baughman, John D. W. Madden, John D. W. Madden, "Simple and strong: twisted silver painted nylon artificial muscle actuated by Joule heating", Proc. SPIE 9056, Electroactive Polymer Actuators and Devices (EAPAD) 2014, 90560I (26 March 2014); doi: 10.1117/12.2046411; https://doi.org/10.1117/12.2046411

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