Self-powered finger motion sensing for piano training based on the ionic hydrogel triboelectric nanogenerator

Wearable sensing technologies have attracted increasing attention for real-time monitoring of human motion and physiological activities. In this study, a PTPAVI-Al³⁺ ionic conductive hydrogel-enabled triboelectric nanogenerator (PA-TENG) is designed as a multifunctional platform capable of converting mechanical stimuli into electrical signals for energy harvesting and autonomous finger joint motion sensing during music training. The PTPAVI-Al³⁺ ionic conductive hydrogel electrode features a hybrid architecture composed of a poly(vinyl alcohol) (PVA) framework and a covalently crosslinked poly(acrylamide-co-1-vinyl-3-butylimidazolium bromide-co-itaconic acid) (PA-VBI-IA) network, in which tannic acid (TA) and Al³⁺ ions cooperatively generate a dense supramolecular interaction network. This hierarchical structure endows the hydrogel with high stretchability, strong self-adhesion, excellent ionic conductivity, anti-swelling behavior, and mechanical robustness. A nylon/polydimethylsiloxane triboelectric pair is employed to assemble a vertical contact-separation PA-TENG, delivering a peak open-circuit voltage (V_OC) of 1080.6 V, a short-circuit current (I_SC) of 74.5 µA, and a maximum power output of 2.1 mW. Moreover, the PA-TENG enables accurate, self-powered monitoring of finger joint motion and applied force during piano training, demonstrating its potential for wearable sensing, skill training, and human-machine interaction applications.