Rapid-Responsive Hydrogel Actuators with Hierarchical Structures: Strategies and Applications

Hydrogel actuators can generate reversible shape deformation in response to external stimuli and show promising applications in many emerging fields. However, the applications of hydrogel actuators are limited by slow actuating performance. Introduction of hierarchical structures can accelerate the response rate of the hydrogel actuators and display fascinating applications. In this review, the development and current situation of hydrogel actuators are briefly introduced first, then the design strategies of hydrogel actuators with rapid response rates, including fabricating an energy storage system, constructing a microporous structure, integrating a micro/nanocomponent, and utilizing electrostatic repulsion, are summarized, followed by the promising applications of rapid-responsive hydrogel actuators. Finally, the challenges and future perspectives are highlighted.