Surface effects on the electromechanical response of miniaturized dielectric elastomer membranes

Dielectric elastomers (DEs) are emerging as promising electroactive polymers for transducers due to their capabilities of large deformation, fast response, and high energy density. As DE transducers are miniaturized to meet low-voltage operation requirements facilitated by advanced fabrication techniques, surface effects, including surface energy density, surface tension, and surface elasticity, become increasingly important in governing their electromechanical performance. In this work, we develop a thermodynamic framework that incorporates surface effects of the elastomer into the modeling of DE membranes and systematically investigate their influence for unconstrained and laterally constrained DE membranes under various loading conditions, including voltage-only actuation, voltage combined with uniaxial or biaxial forces. The theoretical predictions are validated by finite element simulations. Our analysis reveals that while surface effects of the elastomer stiffen the DE membrane and increase the voltage required to achieve a given stretch, the inclusion of surface tension and surface elasticity can suppress or even fully eliminate the electromechanical instabilities. This stabilization is particularly evident in laterally constrained DE membranes, where the combination of pre-stretch and surface effects alters the membranes’ overall deformation mode and enhances the force-strain response by increasing the output work. The analysis also uncovers transitions between wrinkling and pre-stretched deformation states, which are sensitive to surface parameters and applied mechanical forces. These findings highlight the crucial role of surface effects of the elastomer in accurately predicting and tuning the electromechanical behavior of miniaturized DE transducers. This study provides theoretical insight and practical guidelines for the design of miniaturized soft actuators with surface engineering.