Engineering Janus Nanofiber Interfaces for Simultaneous Triboelectric Enhancement and Wearable Comfort

Wearable triboelectric nanogenerators (TENGs) enable self-powered health monitoring by sensing human motion and physiological signals. However, operating at the skin/device interface is usually compromised by perspiration. Here, we present a moisture-wicking Janus bilayer TENG (MW-JBT) that integrates directional moisture transport with dielectric-engineered electrospun nanofibers. The Janus bilayer membrane integrates a tribo-negative hydrophobic poly(vinylidene fluoride-co-hexafluoropropylene)/barium zirconate titanate-silver core-shell nanoparticle (PVDF-HFP/BZT-Ag) nanocomposite layer with a hydrophilic polyurethane (PU) layer. In this architecture, the PVDF-HFP/BZT-Ag side functions as the charge-generating interface, where BZT-Ag core-shell nanoparticles promote dielectric polarization and retention, while the PU side facilitates moisture removal from the interface. Unlike conventional water-resistant TENGs blocking moisture penetration, the asymmetric PVDF-HFP/PU architecture establishes a capillary-driven moisture pathway that actively removes interfacial sweat from the triboelectric surface within 4s. The optimized MW-JBT achieves peak-to-peak outputs of 5.26 µA and 372 V at 100 N and 4 Hz, with a maximum power density of 17 W m^{- 2}. Integrated into a plantar sensing system with a wireless STM32 module and a Minimal RNN classifier, the MW-JBT achieves 88.5% accuracy for fall detection. This work provides an interface-engineered strategy to construct wireless sensors combing self-powered sensing and wearable comfort, enabling home-based healthcare and rehabilitation monitoring scenarios.