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

Abstract

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.

Recent developments in artificial spider silk and functional gel fibers

“…As artificial muscles, hydrogels exhibit several advantages in comparison to other building materials, including a wide range of stimuli-responsiveness, sensitivity, and large-volume deformation. 88 Hydrogels with a high water content are similar to biological muscles. The use of hydrogels as artificial muscles is difficult due to their weak work capabilities and limited mechanical properties.…”

“…Artificial muscles demonstrate immense promise as intelligent materials that can replicate the motion of living organisms without using conventional power systems. As artificial muscles, hydrogels exhibit several advantages in comparison to other building materials, including a wide range of stimuli‐responsiveness, sensitivity, and large‐volume deformation 88 . Hydrogels with a high water content are similar to biological muscles.…”

Liquid metal–hydrogel composites for flexible electronics

“…Electromagnetic actuators have the comprehensive advantages of portability, rapid response and low voltage drive. Daiki Tachibana et al 193 used microfluidic technology to prepare a liquid metal gel fiber as an actuator. Under the driving control of Lorentz forces generated by the current and the magnet, the LM-hydrogel actuator can not only achieve translation, rotation, bending and expansion movements, but also be used as a gripper to grasp and move objects (Fig.…”

Soft Fiber/Textile Actuators: From Design Strategies to Diverse Applications

“…For instance, a fiber/coil-shaped actuator actuated by electromagnetic forces was proposed. 155 Fiber/coil-shaped actuators, with a sheath of sodium alginate and a core of poly(vinyl alcohol) (PVA), were fabricated using microfluidics. Subsequently, the internal PVA was replaced with liquid metal.…”