Hygrothermic Wood Actuated Robotic Hand.

Stimulus-responsive actuators play a vital role in the new generation of intelligent systems. However, poor mechanical performance, complicated fabrication processes, and the inability for complex deformation limit their practical applications. Herein, we overcome these challenges via designing a strong hygrothermic wood actuator with asymmetric water affinity. The actuator is readily constructed by sandwiching a polypyrrole-coated wood with a Ni complex hygroscopic gel top layer for moisture absorption and a polyimide bottom layer as the water barrier. The resulting hygrothermic wood spontaneously stretches and bends itself in response to moisture and thermal/light stimulation. A robotic hand and a series of grippers made of the hygrothermic wood demonstrated dexterous object-hand interactions during grasping and holding, while the reversible hygrothermic property allows the actuator to be potentially applied in fire rescue scenarios to rescue trapped objects. A combination of good mechanical properties, multi-stimulus response, complex deformation, wide working temperature range, low manufacturing cost and biocompatibility were simultaneously realized by one device. It is thus believed that such a strong wood actuator will open up a new avenue for building intelligent robotic hand systems. This article is protected by copyright. All rights reserved.