The movements of soft living tissues, such as muscle, have sparked a strong interest in the design of hydrogel actuators; however, so far, typical manmade examples still lag behind their biological counterparts, which usually function under nonequilibrium conditions through the consumption of high-energy biomolecules and show highly autonomous behaviors. Here, we report on self-resettable hydrogel actuators that are powered by a chemical fuel and can spontaneously return to their original states over time once the fuels are depleted. Self-resettable actuation originates from a chemical fuel-mediated transient change in the hydrophilicity of the hydrogel networks. The actuation extent and duration can be programmed by the fuel levels, and the self-resettable actuation process is highly recyclable through refueling. Furthermore, various proof-of-concept autonomous soft robots are created, resembling the movements of soft-bodied creatures in nature. This work may serve as a starting point for the development of lifelike soft robots with autonomous behaviors.

Macroscopically structured supramolecular hydrogels are appealing platforms for broad applications, ranging from biomedicine to soft electronics; yet, the developed examples are usually static, incapable of evolving their structures and properties over time. Here, we show how the transient assembly of macroscopically structured supramolecular hydrogels can be realized by using shaped chemical fuels. The shaped fuels are made by simply loading high-energy chemicals in solid gels with well-defined shapes. The loaded fuels can diffuse out and generate gradients in the vicinity of the solid gels, thereby driving transient assembly of supramolecular hydrogels that inherit the shapes of the solid gels. The macroscopic structures and lifetimes of the hydrogels can be tuned by changing the shapes and contents of the fuels, respectively. Such a shaped fueling dynamic self-assembly strategy is further designed for dynamic information encryption, whereby the encoded information can only be read for one time and within a defined period.

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