Electroactive Thermoplastic Dielectric Elastomers as a New Generation Polymer Actuators

Abstract

Actuators or transducers, represent devices that directly convert electrical energy to mechanical energy and thus generate a force and motion. The fast growing industries of highly integrated electronics, medicals, and robotics, eagerly demand new types of transducers with flexibility, high energy efficiency and compactness, because conventional actuators including pneumatic actuators, motors, and hydraulic cylinders, have many restrictions such as heavy weight, rigidity, restrictive shape, complex transmission, and limited size. Electroactive dielectric elastomers have garnered much more attention as promising alternative candidates for next generation compact actuators or transducers than other electroactive materials such as electroactive ceramics, shape memory alloys, and even other electroactive polymers like conductive polymers and ionic polymer metal composites, owing to their attractive properties such as large electromechanical strain, fast response, high power to mass ratio, softness, facile proccessibility, and affordability (Pelrine et al. 2000a, 2000b; Shankar et al., 2007a, 2007b). For example, a comparison of the properties of electroactive dielectric elastomers and other widely used transducer materials lists in Table 1. Piezoelectric materials have quite fast and high energy efficient response, but produce a limited strain (Furukawa & Seo, 1990). Shape memory alloys (Lagoudas, 2008), conducting polymers (Bay et al., 2004) and ionic polymer metal composites (Nemat-Nasser & Wu, 2003) are capable of producing relatively large strain, but they suffer pretty slow response and poor coupling efficiency. In contrast, the electroactive dielectric elastomers have much superior actuation properties than others.