Moisture-Responsive Paper Robotics

Abstract

Origami structures held promise for their flexibility, simultaneous responsiveness, and adaptability, yet they are vulnerable due to the hygroscopic property when exposed to the humid environments. However, the patterning of hydrophobic material along the design enhances the controllability of paper for self-folding to robotics locomotion. The capillary action of sprayed water molecules is localized through the number or sizes of hydrophilic channels defined by the printed wax patterns resulting in large deformation to form various 3D geometries. The patterned paper performed folding actuation with water and unfolding behavior with evaporation without being mechanically manipulated by external forces or moments. The paper actuators further enable the sequential self-folding along the multiple hinges for the cube and diamond structures. Advances in soft robotics for practical applications, the utilization of different swelling/shrinking properties with water and kirigami-inspired programmable structures interact with the lightweight and non-planar objects. The anisotropic properties of paper in response to water spraying combined with folding/unfolding deformations permit the fold-to-pop-up robots for biomimetic locomotion on the plane or water. Two robots deform their body to move forward through bending-relaxation gait.