Harnessing the Day-Night Rhythm of Humidity and Sunlight into Mechanical Work Using Recyclable and Reprogrammable Soft Actuators.

Toward a sustainable society, soft actuators driven by environmentally friendly energy from nature are of great social and economic significance. Meanwhile, recyclability, repeated reconfiguration for other use, and complex three-dimensional (3D) geometries are also essential for mitigating the energy crisis and practical application demands. Here, we integrate all of the above features in one actuator using vitrimers with exchangeable disulfide links. By reconfiguration, welding, patterning, and kirigami techniques, complex 3D actuators can be easily fabricated, which can be repeatedly reconfigured for other applications to save cost in new material preparation. These actuators operate synergistically with the day-night rhythm of humidity and sunlight without the need of extra energy input.