Superhydrophilic Polyurethane Nanofibers for Janus Electrodes in Human Physiological Signal Detection

Flexible electronic skin has experienced rapid development in health monitoring, human–machine interfaces, and medical diagnostics. However, improving the microenvironment of the human skin surface without affecting electrical signals remains a significant challenge. Herein, polyurethane nanofiber membranes produced via electrospinning are treated with plasma and stable superhydrophilic SiO₂–TiO₂ coating. A second layer of hydrophobic nanofibers is then spun on its surface, forming Janus membranes. Silver nanowires are incorporated into these Janus membranes through vacuum filtration, creating a breathable flexible electrode. Residual solvents promote fiber bonding at interfaces, preventing layer separation and ensuring electrode stability. The flexible Janus electrode demonstrates a combination of functional properties, providing stretchability, breathability, conductivity, and antibacterial effects simultaneously. Compared to the commercial gel electrode, it also demonstrates stable directional water transport and resistance to mechanical stress, efficiently channeling sweat to the surface for rapid evaporation. This capability helps regulate skin temperature and humidity, thereby enhancing comfort during wear. Additionally, the electrode supports the accurate monitoring of human electrocardiographic and electromyographic signals, offering a promising tool for health monitoring and personal protection.