Ultrasoft and fast self-healing poly(ionic liquid) electrode for dielectric elastomer actuators

Abstract

Dielectric elastomer actuators (DEAs) exhibit large actuation strains, lightweight, and fast response, making them a promising candidate for soft robotics and soft grippers. Ionogels have been used as the electrodes in DEAs to offer thermostability and self-healability, however, typically the elastic modulus of the self-healing ionogel electrodes is of several tens of kPa (or higher), limiting the actuation strain performance and self-healing speed of the DEA. In this work, a poly(ionic liquid) (PIL) electrode with an ultralow elastic modulus of 3.4 kPa and rapid self-healing within 10 s in ambient and underwater conditions is achieved through ionic interaction regulation. The resultant DEAs realized an area strain of 63.2%, and maintained the strains after 10 s of self-healing at room temperature, outperforming other reported DEAs with self-healing electrodes. With the PIL electrode, a soft gripper composed of two bending DEAs is fabricated to gently handle soft and delicate objects in both air and underwater settings, retaining functionality even after damages due to self-healing of the PIL electrodes. The PIL electrode advances the development of electrically driven soft robotics for exploration in harsh environment or underwater settings. Dielectric elastomer actuators using ionogel electrodes are promising candidates for soft robotics, although their mechanical properties can limit actuation strain and self-healing capabilities. Here the authors report a poly(ionic liquid) electrode designed to improve mechanical properties and self-healing, thereby enabling higher actuation strains and recoverability.