PDMS/graphite stretchable electrodes for dielectric elastomer actuators

Abstract

Dielectric elastomer actuators (DEAs) consist of an elastomer sandwiched between two electrodes, and they undergo a large in-plane expansion upon the application of an electric field. They therefore require compliant electrodes that can stretch tens of percent. The most commonly used electrode material is carbon grease, which smears easily and is difficult to pattern. This paper outlines the fabrication and performance of a novel polydimethylsiloxane (PDMS) composite having a 15 wt% loading of exfoliated graphite (EG). This new material has a Young's modulus of only 0.9 MPa and a conductivity of 0.15 S/cm. Unlike other composite electrode materials, the Young's modulus of the PDMS/EG increases only slightly, by a factor of two, upon addition of the EG. Furthermore, the PDMS/EG composite is patternable and will not rub off. DEAs were fabricated with 20:1 PDMS as the elastomer using this new electrode material. The actuation strains were equal to those of 10:1 PDMS DEAs with carbon grease electrodes under the same electric field. Elastomer/EG composites may also find applications in areas such as flexible electronics, robotics, strain gauges, and sensors.