Soft actuators driven by humidity and temperature based on plant parchment

Soft actuators driven by humidity and temperature have attracted widespread attention. These robots transform external stimuli into controlled deformation of the shape of the material. Here, we designed and produced a series of actuators by using plant parchment to achieve reversible deformation under humidity and heating conditions. The difference in fiber arrangement direction and inner surface structure leads to the anisotropy of plant parchment, which causes a large actuation at a relative humidity of 100% (maximum curling curvature of 4 cm
^-1
). Cutting the plant parchment into strips that are arranged at different angles to the fiber direction, plant parchment has multiple patterns of movement such as bending, curl and spiral. With the durability of plant parchment, we apply it to crawling robot, weightlifting, four-petal flower, the stereo windmill. Humidity and heat are converted into mechanical energy, and we believe that this shape-programmable plant parchment is suitable for making soft robots.