LAUSR

Gecko-inspired dry adhesion has been attracted much attention for many applications such as soft grippers and wall-climbing robots, which, however, demonstrates stable adhesion on flat surfaces and small adhesion on non-flat surfaces. In practice, the geckos' capability of walking upside down on both flat and non-flat surfaces comes from the combined action of adhesive structures for passive adhesion and toe muscles for stiffness modulation. Inspired by this behavior, this study proposes a hierarchal adhesive structure for a high and switchable adhesion on non-flat surfaces. The three-layer adhesive consists of a mushroom-shaped structure top layer, stiffness modulation thermoplastic polyurethane (middle layer), and an electrothermal film (bottom layer) that mimic the epidermal adhesive structures, toe muscles, and electromyographic signal, respectively. Through the tunable structural stiffness controlled by adjusting the voltage, the adhesive force can be increased by one or two orders of magnitude compared to the conventional adhesive structures, and further used for attachment and detachment functions. The gecko-inspired soft gripper is successfully tested as a pick-up and drop-down system for transporting a surface with different features, which has great application potential in industrial lines and daily life.