Flexible and multifunctional triboelectric nanogenerator based on liquid metal/polyvinyl alcohol hydrogel for energy harvesting and self-powered wearable human–machine interaction

Hydrogel-based triboelectric nanogenerator (TENG) has a promising applied prospect in wearable electronic devices. However, its low performance, poor stability, insufficient recyclability and inferior self-healing seriously hinder its development. Herein, we report a robust route to a liquid metal (LM)/polyvinyl alcohol (PVA) hydrogel-based TENG (LP-TENG). Owing to the intrinsically liquid feature of conductive LM within the flexible PVA hydrogel, the as-prepared LP-TENG exhibited comprehensive advantages of adaptability, biocompatibility, outstanding electrical performance, superior stability, recyclability and diverse applications, which were unattainable by traditional systems. Concretely, the LP-TENG delivered appealing open circuit voltage of 250 V, short circuit current of 4 μA and transferred charge of 120 nC with high stability, outperforming most advanced TENG systems. The LP-TENG was successfully employed for versatile applications with multifunctionality, including human motion detection, handwriting recognition, energy collection, message transmission and human–machine interaction. This work presents significant prospects for crafting advanced materials and devices in the fields of wearable electronics, flexible skin and smart robots. Graphical abstract