A flexible triboelectric nanogenerator-enabled insole for self-powered gait monitoring in football applications

The integration of self-powered wearable sensors is emerging as a transformative approach in smart sports analytics and athletic performance monitoring. In this work, we present a flexible and low-cost fiberglass cloth triboelectric nanogenerator (FC-TENG), constructed from a laminated structure of fiberglass cloth and cotton fabric. Operating in a vertical contact–separation mode, the FC-TENG demonstrates excellent triboelectric performance, with a high open-circuit voltage (V_OC, 172.7 V), short-circuit current (I_SC, 30.4 μA), and transferred charge (Q_SC, 89.6 nC) under 2 Hz excitation, along with a maximum power density of 158.7 mW/m² at an optimized load of ∼10 MΩ. The device also exhibits robust capacitor charging capability and frequency-dependent output characteristics. To explore its practical value, the FC-TENG was integrated into the heel region of a football shoe and employed as a self-powered bio-mechanical sensor for real-time monitoring of foot-ground interactions during typical football activities such as dribbling, shooting, passing, and ball control. The system enables accurate recognition of gait phases, walking speed variations, and motion states (e.g., walking, running, jumping), solely based on triboelectric signal features—without requiring external power sources. Furthermore, abrupt signal interruptions enable fall detection, offering potential applications in sports injury prevention and athlete safety. This study demonstrates a scalable and wearable triboelectric sensing platform tailored for next-generation self-powered football training, real-time movement classification, and personalized sports performance optimization.