Protein Gel Phase Transition: Toward Superiorly Transparent and Hysteresis‐Free Wearable Electronics

Abstract The next generation of wearable electronics for health monitoring, Internet‐of‐Things system, “interface‐on‐invisible,” and green energy harvesting require electrically conductive material that is superiorly transparent, negligibly hysteretic, industrially feasible, and highly stretchable. The practical potential of ionic hydrogel is challenged with obvious hysteresis and a limited sensing range due to relative delamination and viscoelastic performance. Herein, a novel liquid conductor, termed as egg white liquid, is developed from self‐liquidation of egg white hydrogel, and the liquid not only inherits the designed architecture from a hydrogel predecessor but also achieves comparable conductivity (20.4 S m −1 ) to the ionic hydrogel and ultrahigh transparency (up to 99.8%) . Moreover, the 3D‐printed liquid–elastomer hybrid exhibits excellent conformability, remarkable sensitivity with negligible hysteresis (0.77%), and the capability of monitoring human motions and dynamic moduli is further demonstrated. The liquid nature inspires a gesture‐controlled touchless user interface for front‐end electronic systems. Furthermore, mechanical energy harvesting and pressure sensing are evidenced by exploiting this liquid conductor into a triboelectric nanogenerator. Notably, the as‐prepared liquid via subsequent phase transition possessing superior transparency, ultralow hysteresis, economic benefit, and unique liquid phase may potentially fuel the development of a new class of wearable electronics, human–machine interface, and clean energy.