Electrically driven hydrogel actuators: working principle, material design and applications

Smart hydrogels, renowned for their adaptability to environmental changes, have found widespread utility in the realms of bioelectronics and bio-machinery, encompassing applications such as drug delivery, tissue engineering, physiological sensing, and cellular regulation. Among these applications, electrically driven hydrogel actuators stand out due to their superior control, swift responsiveness, and seamless integration with electronic systems. They hold great potential in the development of multifunctional hydrogel-based machines, including soft robots and artificial muscles. Despite significant progress in the field of electrically driven hydrogels, including advancements in material design, operational principles, microfabrication techniques, and performance optimization across diverse applications, a comprehensive review dedicated to this topic remains notably absent. This review aims to provide an all-encompassing perspective on electrically driven hydrogel actuators, delving into their foundational principles, molecular and composite designs, fabrication methodologies, device configurations, and their applications in the realms of soft robotics and bio-machinery. Furthermore, it highlights the existing performance constraints, explores strategies for enhancement, and outlines potential future avenues for the utilization of electrically driven hydrogels.