A Multi-Mode, Multi-Frequency Dielectric Elastomer Actuator

This paper presents a principle to develop multi-function dielectric elastomer actuators (DEAs) that can concurrently accomplish linear actuation and sound generation through a single electrical input. A centimeter-scale cone-shaped DEA is fabricated using silicone-based dielectric and electrodes. Measurements of the vibro-acoustic response reveal that the pumping deformation of the DEA contributes to a negligible extent in the sound generation, which is hence ascribable to higher order structural modes whose frequency pass-band is highly uncoupled from that of the pumping mode. Exciting the DEA with a multi-chromatic input voltage allows achieving strokes close to 1 mm or blocking forces over 0.5 N, while simultaneously generating sound pressure levels over 60 dB, regardless of possible forces and/or mechanical constraints on the DEA pumping motion. The ability of the DEA to concurrently generate linear actuation and sound is demonstrated via proof-of-concept tests: the DEA can reproduce music, while at the same time generating a deformation pulse or lifting a load comparable with its own blocking force. Furthermore, measuring the current generated by the DEA allows detecting deformations impressed by the exterior and use the DEA as an active audio-tactile interface, which produces a combined vibro-acoustic stimulus in response to a user's touch.