Instant-healing hydrogel-based triboelectric nanogenerator fornon-contact sensing and energy harvesting

Flexible multifunctional hydrogel-based triboelectric nanogenerators (TENGs) have emerged as highly promising candidates for energy harvesting and sensing applications. In this study, a novel PTC-1 hydrogel comprising polyvinyl alcohol (PVA), hydroxylated multi-walled carbon nanotubes (HO-mCNT), and tannic acid (TA) is synthesized, exhibiting exceptional electrical performance, environmental adaptability, and multifunctionality. The incorporation of HO-mCNT promotes the formation of an efficient and homogeneous conductive network, enabling the TENG to achieve a high open-circuit voltage (Voc) of 398 V, short-circuit current (Isc) of 4.60 mu A, and transferred charge (Qsc) of 64.76 nC, while maintaining excellent durability with minimal output degradation after 10,000 cycles. Furthermore, the hydrogel demonstrates remarkable anti-freezing properties down to-20 degrees C, owing to glycerol (GL)-induced inhibition of ice crystallization, as well as superior water retention (retaining 52.72 % of its initial mass after 20 days) due to the synergistic effect of GL and Ecoflex encapsulation. The dynamic hydrogen bonding and TA crosslinking bestow the hydrogel with self-healing capability, achieving complete recovery spontaneously under ambient conditions. The TENG exhibits exceptional performance in diverse applications, including handwriting recognition, where distinct voltage signatures are recorded for letters and Morse code signals, and non-contact sensing, demonstrating high sensitivity to object size and proximity. Additionally, the device efficiently harvests biomechanical energy, successfully powering an LED matrix and charging a 47 mu F capacitor to 2 V within just 10 s. This study highlights the potential of hydrogel-based TENGs as next-generation wearable energy devices and self-powered sensors for intelligent human-machine interfaces, environmental monitoring, and energy harvesting technologies.