Actuation From Directional Deformation Based on Composite Hydrogel for Moisture-Controllable Devices

Reconfigurably adaptive devices through the shape change offer reasonably appropriate and recoverable departures in shape, in order to satisfy changing environmental constraints or operational demands. Here, we demonstrated the humidity-responsive directional-deformation actuators based on interpenetrating composite polymer hydrogel, which were applied as moisture-controlled automatic curtain and power-OFF safety switch. In the double-layer actuators, a rigid stripe of interpenetrating polymer hydrogel by photolithography were aligned into humidity-responsive hydrogel. Through adjusting the angle of interpenetrating polymer stripe, the strip actuators deformed in various deformation orientations, including horizontal, perpendicular, left-handed helix, and right-handed helix deformation with different angles. The directional-deformation actuators were suitable as environmentally adaptive devices in the automatically roll-up and fall-down “curtain” application corresponding to humidity change, and automatically power-OFF safety switch when ambient humidity suddenly increased. These examples of model application exhibited potential significance of the actuators as soft robots.