Spray-Printing and Spin Methods to Fabricate Multilayered Dielectric Elastomer Actuators Embedded with Liquid Metal Electrodes

As high-efficiency electrical responsive materials, multilayer dielectric elastomer actuators (DEAs) have been widely adopted in fabricating soft robotics. Among various candidate materials, liquid metal (LM) is especially suitable to be used as a flexible electrode for DEAs owing to its high electrical conductivity and negligible stiffness. However, limited by the printing techniques, former works still did not achieve multilayer DEAs embedded with LM electrodes. To further push forward the progress in this direction, the present work proposes an easygoing way for fabricating flexible LM electrodes by combining spray-printing and high-speed spin procedures together. Over the conceptual experiments, the effects of rotational speed on surface topology, mechanical behaviors, and electrical properties of LM have been investigated and an optimum value of 4000 rpm is recommended for removing excess LM. Following that, the DEA thus integrated with the LM electrode presents negligible stiffness change compared with pure elastomer and displays rather good resistance cyclic behaviors. Finally, a multilayer cylindrical DEA device with six layers of LM electrodes and seven layers of silicone film is constructed and demonstrated to generate a blocked force of 8.76 mN at a bipolar sinusoidal voltage of 1000 V and 1 Hz, warranting the feasibility of the current approaches. This work expands the repertoire of multilayer DEA fabrication methods and holds significant promise for soft robotics in the near future.