Harnessing electromechanical membrane wrinkling for actuation

Dielectric elastomers are soft electromechanical transducers that can exhibit unstable wrinkling behavior under large electric fields. This instability can be exploited by optimizing electrode boundaries to accentuate or attenuate localized wrinkling. An analytical model is presented, which demonstrates that the critical electric field to induce wrinkling can be lowered as the electrode geometry changes from convex to concave. This allows a single dielectric elastomer membrane to generate either biaxial or uniaxial extension in specific regions. A prototype 56 μm thick membrane actuator incorporates this principle to generate an in-plane rotational output, producing an actuation stroke of 15.7°.