Skin-inspired self-healing semiconductive touch panel based on novel transparent stretchable hydrogels

With the increasing importance of human–machine interactions, stretchability, biocompatibility, and self-healing behavior will play a more significant role in next-generation touch panels so as to allow integration with the human body. However, profound challenges remain because the electrodes of most touch panel are constructed by stiff and brittle materials lacking a self-healing capacity. Herein, we demonstrate a semiconductive touch panel that adopts a capacitive touch-sensing system, based on a poly(N,N′-dimethylacrylamide)–titanium dioxide nanocomposite hydrogel as a transparent conductor. The panel exhibited high stretchability, softness, low parasitic capacitance, high resolution, fast response, and instant functionality recovery upon damage. The panel was stretched to more than 1100% areal strain and could still be operated as an input device without sacrificing its functionalities. Furthermore, the distortion near the edge of the panel, owing to the nonlinearity of the resistance proved by the electrical finite element method simulation, became weaker after optimizing with a four-terminal pattern through 3D printing. An epidermal touch panel adhered to the human skin, and demonstrated strong performance and self-healing ability by being able to write words, play chess, and play games.