Nature-Driven Biodegradable Composite Film-Based Triboelectric Nanogenerator for Self-Powered Sports Activity Monitoring Applications

The integration of sustainable, nature-derived materials into triboelectric nanogenerators (TENGs) presents a transformative approach to eco-friendly energy harvesting for wearable technologies. Here, we introduce a highly tribo-positive composite film fabricated from agar and beetroot aimed at self-powered sports monitoring applications. The agar matrix forms a porous, mechanically robust hydrogel network, while beetroot-derived components increase the density of polar hydroxyl and carboxyl groups that can form strong dipoles or partially ionize during contact electrification; together with betanin pigments, these functionalities enhance electron-donating capability, surface polarity, charge trapping, and overall surface charge density through their synergistic interaction with the polymer matrix. The fabricated device demonstrates exceptional triboelectric performance, achieving a voltage of ∼380 V and a power density of ∼6 W m –2 under gentle mechanical excitation (4 Hz, 20 N), outperforming many synthetic polymer-based counterparts. The TENG attains an ultrahigh sensitivity of 14.4 V kPa –1 within the pressure range of 3–45 kPa, demonstrating its potential uses in monitoring human mobility as a self-powered pressure sensor. We demonstrate a fully biodegradable TENG using beetroot-agar films, with controlled degradation using diluted PBS (phosphate-buffered saline) solution at ambient temperature, eliminating electronic waste. Leveraging its inherent biodegradability, flexibility, and sensitivity, the agar-beetroot TENG is seamlessly integrated into self-powered wearable sensors for real-time monitoring of athletic movements, including walking, running, clicking, and jumping. Moreover, the TENG exhibits a motion detection accuracy of 99.24%, as determined by a deep learning model. This work underscores the potential of biosourced, waste-derived composites as high-performance tribo-positive materials, advancing the development of green electronics for next-generation wearable systems in sports biomechanics, healthcare, and IoT applications.