Breathable nanomesh electrodes with improved water resistance and stretchability for skin impedance monitoring

Skin impedance reflects both the barrier function and psychophysiological state of the human body, but long-term monitoring remains challenging due to the lack of electrodes that simultaneously offer water resistance, stretchability, and breathability. In this study, we developed poly(vinyl alcohol)/waterborne polyurethane (PVA/WBPU) blend nanomesh electrodes with controlled polymer composition to address these requirements. Electrospinning produced nanofibers with an island–sea morphology, where partial dissolution of PVA enabled temporary skin adhesion while residual WBPU maintained structural integrity. The optimized PVA/WBPU = 5/5 electrodes showed minimal resistance increase (1.02-fold) after 24 h of continuous water flow and retained conductivity under 80% strain and after 1000 stretch cycles. When applied to the palm, they maintained stable resistance ( < 50 Ω) for at least 4 h, whereas PVA-only electrodes frequently exhibited resistance increases above 1 kΩ or electrical disconnection. These results indicate that controlling the PVA/WBPU blending ratio ensures mechanical and electrical stability while preserving breathability, establishing a materials design strategy for long-term, skin-conformable, and breathable bioelectronic interfaces.