A paper-based wall-climbing robot enabled by electrostatic adhesion

In this paper, we report a paper-based wall-climbing robot capable of climbing vertical walls of different materials. The robot, made from paper and shape memory alloy (SMA), can be controlled to climb walls under certain combinations of activation patterns of electrostatic adhesion and contraction of the SMA. Electrostatic adhesion is applied using a paper structure with embedded interdigitated electrodes. This structure, fully compatible with the paper-based robot, is able to output strong and reliable adhesion forces (the resultant friction force can be as high as 1.65 N on specific substrates), and can be easily turned on and off using a commercial high-voltage converter. The SMA embedded in the robot is employed to deform the robot body and induce contracting displacements while being activated. The elastic energy stored in the robot body allows it to complete a repeatable actuation cycle by recovering the SMA automatically after its contraction. With above structures, we demonstrate the walking and climbing ability of this robot with a locomotion speed of 1 mm/s. The climbing of a vertical wall along both the vertical and horizontal directions is achieved.