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

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.