Electrically Controlled Gel Actuator Using Liquid Metal Electrode

This report demonstrates an electrically controlled gel actuator by a three-dimensional(3D) helical structure with liquid metal. Previously, 3D helical wiring with liquid metal was established based on core-shell hydrogel microspring fabricated using a double bevel-tip nozzle [1]. In general, gel actuators require change of environmental parameter such as temperature in entire chamber and/or needs harsh environment such as strong acid solution. Therefore, it is difficult to control actuations of gel actuators electrically, and individually. In this study, liquid metal as conductive materil was injected into core part of microspring, which formed liquid metal spring which has 3D helical structure. A rod of a thermoresponsive gel was inserted into the center of the liquid metal spring in order to an actuator. Current was applied to the spring to heat the entire actuator. The rod of temperature responsive gel was warmed up and shrinks together with the spring. As a result, we succeeded in shrinking and bending of the gel actuator by 36% and 44 ° by electrical control. In addition, actuations of each gel actuator inside same chamber was controlled individually. Our gel actuators present an important advancement towards development in several fields including soft robots, microactuators, drug delivery systems (DDS).