Dielectric Elastomers as Electroactive Polymers (EAPs): Fundamentals

Abstract

Dielectric elastomer transducers are a class of electroactive polymers that operate based on the interaction of quasi-static electric charges with deformable dielectric and electrode materials. The basic functional element of a dielectric elastomer transducer is a thin dielectric film sandwiched between electrodes. When a dielectric elastomer transducer is used as an actuator, voltage applied across the film causes unlike charges on opposite electrodes to attract and like charges on each electrode to repel. The net result is compressive stress in the thickness direction and tensile stresses in the planar directions. When a dielectric elastomer transducer is used as a generator or sensor, stretching the film will vary the voltage and energy state of applied charges (i.e., the functional element is a stretchable capacitor). Analysis of a simplified model derives an expression for the effective total strain that is twice that for a rigid plate capacitor. The performance of dielectric elastomer transducers is limited by lifetime issues associated with dielectric breakdown and mechanical failure of the film or electrodes. The basic functional element can be incorporated into practical transducers in a wide range of configurations. The particular configuration chosen depends on many factors, including the magnitude of the desired strain or force, the available space or desired form factor, and the required bandwidth (speed of response).