Wearable cotton fabric-based single-electrode-mode triboelectric nanogenerator for self‑powered human motion monitoring

Wearable triboelectric nanogenerators (TENGs) as self-powered sensors to monitor human motion have acquired enormous research interest owing to their low cost and highly efficient mechanical energy-harvesting property. However, development of cellulose fabric-based TENGs with excellent breathability, durability, and shape adaptivity to minimize user discomfort remains a challenge. Herein, a flexible and stretchable cotton fabric-based single-electrode-mode TENG was developed for mechanical energy harvesting and self-powered sensing to detect human motion behaviors. Breathable cotton/ammonia (95% cotton, 5% spandex) blended composite fabric was employed as flexible electrode in TENG via in situ polymerization of polypyrrole, followed by spattering of silver nanowires. Afterward, the polytetrafluoroethylene layer was coated on the surface as a tribo-negative material. The prepared TENG can maintain a stable output voltage of approximately 0.3 V under a force of 4 N at 2.5 Hz frequency. The resulting TENG also exhibited excellent air permeability of 1329.134 mm/s, moisture permeability of 399.7 g/m 2 ·24 h, and cycle stability (above 4000 cycles) and can act as a wearable and sustainable power source for powering electronic devices. Furthermore, the cotton fabric-based TENG can be attached to the finger, wrist, or elbow as a reusable self-powered strain sensor for motion detection due to its shape adaptivity and durability. This work provides a useful design strategy for fabrication of wearable TENGs for energy harvesting and human motion monitoring. Graphical abstract