A 3D printed serrated contact structure triboelectric nanogenerator for swimming training safety monitoring

The wearable electronic devices integrated with 3D printing have attracted much attention, but the continuous power supply demand and limited application scenarios have limited their development. Here, we propose a 3D printed serrated contact structure triboelectric nanogenerator (S-TENG) designed for mechanical energy harvesting and swimming training safety monitoring. Leveraging the advancements in 3D printing technology, we created a flexible, lightweight sensor integrated with polytetrafluoroethylene (PTFE) and polyethylene terephthalate (PET) films on a serrated substrate. This configuration enhances the contact surface area, leading to a significant improvement in energy harvesting efficiency compared to flat structures. Specifically, the serrated structure resulted in a 64 %, 63 %, and 47 % increase in open-circuit voltage (V_oc), short-circuit current (I_sc), and transferred charge (Q_sc), respectively, owing to the contact area and unique surface functional structure. The S-TENG device exhibits excellent performance under various bending angles, with V_oc, I_sc, and Q_sc reaching up to 98.04 V, 4.35 μA, and 38.51 nC at 90° bending. Additionally, the S-TENG maintains stable output in different humidity environments due to its fully encapsulated design, ensuring reliable operation in aquatic settings. The S-TENG can accurately measure elbow swing amplitude and frequency, providing valuable real-time data for athletes and coaches. The S-TENG's ability to detect irregular movements and potential drowning incidents underscores its promise in enhancing swimmer safety. This research demonstrates the S-TENG's utility in both energy harvesting and motion monitoring, paving the way for advanced wearable sports sensors in various athletic disciplines.