Recently emerged electronic skins with applications in on-body sensing and human-machine interfaces call for the development of high-performance skin-like electrodes. In this work, we report a highly robust, transparent, and breathable epidermal electrode composed of a scaffold-reinforced conductive nanonetwork (SRCN). Solution-dispersed Ag nanowires, through facile vacuum filtration, are embedded into a scaffold made of polyamide nanofibers. Optical transmittance of 84.9% at 550 nm wavelength is achieved at a significantly low sheet resistance of 8.2 Ω sq-1. The resistance of the SRCN only slightly increases by less than 0.1% after being bent for 3000 cycles at the maximum curvature of 300 m-1 and by less than 1.5% after being dipped in saline solution for 2500 cycles. The excellent robustness is attributed to the reinforcement from the nanofiber-based scaffold as a backbone that maintains the connections among the Ag nanowires by undertaking most of the loaded stress. The SRCN not only forms tight and conformal bonding with the target surface but also allows the evaporation of perspiration, making it suitable as an epidermal electrode for long-time use. Furthermore, fine and clean-cut circuit patterns with a line width on the micrometer scale can be readily prepared, paving the way for fabricating sophisticated functional electronic skins.
Keywords: electronic skin; epidermal electrode; flexible electrode; nanofibers; silver nanowires.