The transverse strain response of electroactive polymer actuators

Some electroactive polymers show large electric-field-induced strain. However, it is difficult to characterize the transverse strain response, especially the dynamic response, under high driving electric fields. In this work, a transverse strain measurement system based on a ZYGO laser Doppler interferometer has been developed. This system can measure transverse strain responses of polymer actuators of different sizes over a wide displacement and frequency range. By using this system, we have investigated the electric-field-induced strains of electroactive polymer actuators fabricated from silicone (Dow Corning HSIH RTV) films. The static and dynamic strains of the actuators have been measured under various driving electric fields and mechanical loads. Our results show that the polymers exhibit a non-linear relationship between strain and driving field. Mechanical loads have a significant effect on transverse strain responses. Transverse strains of 3.25% (static) and 2.08% (dynamic at 1 Hz) have been obtained under a load-free condition. Our experimental results can be understood on the basis of hyperelastic theory. The actuation of an electroactive polymer actuator is not only determined by its material properties, but also by the actuator structure.