Mechanically robust and breathable ultrathin nanofiber/hydrogel composite electronic skin for continuous electrophysiological signal acquisition.

Flexible bioelectronic devices are crucial for continuous, non-invasive health monitoring, yet achieving ultrathin structures while maintaining mechanical stability and signal fidelity remains challenging. Herein, an ultrathin fiber-reinforced hydrogel electronic skin (CFPIG) with a thickness of ~5.3 μm is developed by embedding polyurethane (PU) nanofibers into a hydrogel matrix combined with a freeze-thaw/UV dual-crosslinking strategy. This synergistic design significantly enhances crystallinity and mechanical performance, achieving a tear strength of 1.3 kJ·m-2, toughness of ~621 kJ·m-3, and stable performance after 300 stretching cycles at 60% strain. Incorporation of the ionic liquid BMIM OTf further constructs an efficient ion-conduction network, improving electrochemical performance. Benefiting from the synergistic effect of the ultrathin structure and porous fiber network, CFPIG exhibits excellent skin conformability, stable interfacial adhesion energy (~158 μJ·cm-2), and high water vapor permeability (~1690 g·m-2·day-1), enabling long-term comfortable skin attachment. CFPIG enables high-fidelity acquisition of multimodal electrophysiological signals, including EMG, ECG, and EEG, with low noise and drift under dynamic conditions. Combined with convolutional neural network analysis, the system achieves over 95% accuracy in hand gesture recognition, demonstrating strong potential for wearable health monitoring and intelligent human-machine interaction systems.