Thermoresponsive E-Skin with Reversible Sweat Transport

Electronic skin (e-skin) that adapts to dynamic environments requires simultaneous regulation of moisture and heat transport while maintaining reliable sensing capability. Here, a temperature-responsive electrode based on a polypyrrole@poly(N-isopropylacrylamide)@cellulose acetate)/poly[ N,N -dimethyl (methacryloylethyl) ammonium propane sulfonate]@cellulose membrane (PPy@PCA/PCM) bilayer is reported, which exhibits complementary wettability switching and reversible unidirectional water transport. At low temperatures, the electrode preserves moisture and heat, maintaining skin hydration level and temperature ≈4 and ≈5 °C higher than bare skin, respectively. At elevated temperatures, the wettability gradient reverses, promoting sweat evaporation and heat dissipation, with hydration level and temperature ≈6 and 4.2 °C lower than bare skin, respectively. Integrated into e-skin, the electrode enables real-time hydration and temperature sensing while dynamically regulating moisture and thermal flux when the environment changes, avoiding skin erythema after long-term wear. Moreover, the PPy@PCA/PCM electrode shows excellent mechanical durability, chemical stability, and cytocompatibility. This adaptive electrode design offers a versatile strategy for multifunctional e-skin that simultaneously ensures physiological signal fidelity and enhances user comfort under varying conditions.