Directional Moisture-Wicking Janus Triboelectric Nanogenerator for Self-Powered Health Monitoring

Wearable devices based on triboelectric nanogenerators (TENGs) have demonstrated immense potential for the real-time monitoring of physiological signals. However, moisture accumulation on the device during use not only reduces wearing comfort but also easily causes charge dissipation at the triboelectric interface, acting as a bottleneck that restricts their practical applications. To overcome this challenge, this work innovatively proposes a synergistic strategy to design a Janus composite fibrous membrane possessing both directional water transport and excellent triboelectric properties via a bilayer electrospinning technique. The membrane consists of a hydrophobic poly(vinylidene fluoride) (PVDF) layer and a hydrophilic polyacrylonitrile (PAN) layer. By constructing significant gradients in fiber pore size and wettability, ultrafast directional water transport (<10 s) is achieved. This study ingeniously incorporates PDA@MXene two-dimensional materials into the hydrophilic PAN layer. Leveraging the self-assembly of PDA on the MXene surface, the active sites of the material are increased, and charge-trapping networks are constructed through abundant hydrogen bonds. This unique charge-anchoring effect synergizes with the highly electronegative hydrophobic layer to significantly enhance the triboelectric output, yielding an open-circuit voltage of up to approximately 150 V and a peak power density of 302.6 mW/m 2 . The device can sensitively recognize various physiological activities, including human gait, breathing patterns, and joint movements. The Janus fibrous material developed in this study provides an innovative strategy to resolve the critical dilemma of balancing moisture management and electrical performance in practical TENG applications, demonstrating broad application potential.