Ultrafast and Highly Deformable Electromagnetic Hydrogel Actuators Assembled from Liquid Metal Gel Fiber

Hydrogel actuators are ultrasoft and pliable but achieving high driving speeds with large deformation and fine local controllability is difficult because the driving force originates from the external air pressure or heat, and the base material is fragile. Herein, hydrogel actuators that allow high-speed driving and large deformation with high-frequency local controllability while maintaining softness are fabricated based on liquid metal gel fibers as electrodes by using microfluidic technology. The Lorentz force produced by an electric current and a magnet is used for actuation control. An ultrafast response of 260.5 mm s(-1) with high-frequency controllability (6 Hz) and a large deformation of 172% with hydrogel actuation are observed. As proof of concept, moving stages, micromixers, and grippers exhibiting high speeds with high mechanical deformability while maintaining the inherent characteristics of hydrogel phases are demonstrated. Different hydrogels can be used with the proposed actuator architecture and fabrication scheme, enabling different functionalities.