Paper Robotics: Self‐Folding, Gripping, and Locomotion

Abstract

Abstract Soft robotics driven by origami can fundamentally advance robotic functionalities by significantly improving continuum, compliance, and configurability. Here, a new field is proposed, “paper robotics,” which is based on moisture‐responsive self‐folding of paper substrates into functional 3D machines using origami‐inspired techniques. By properly designing a hydrophobic wax layer and a hygro‐expandable hydrophilic layer, printed bilayer paper will fold automatically into desired shapes through anisotropic swelling that occurs when water is sprayed on the structure. The bilayer actuators can be readily fabricated on paper by the asymmetrical penetration of wax that is printed on both sides of the paper. The patterned paper automatically folds when water is added and unfolds as the water evaporates. The structure can perform various mechanical functions, including gripping and biomimetic locomotion. One of the practical applications, a kirigami paper robotic finger as an electrical switch, is also demonstrated. The functional mechanism based on the swelling and shrinking properties of paper is modeled and critical parameters for the design of the bilayer actuation are thoroughly characterized. This work will be a starting point for paper robotics and open new avenues to merge soft robotics and origami techniques.