Flowing water-based tubular triboelectric nanogenerators for sustainable green energy harvesting

The green energy present in flowing water is underused owing to lack of environmentally acceptable and sustainable energy harvesting technologies. The triboelectric nanogenerators (TENGs) have received significant attention as a prospective technological advancement due to their simple structure and multiple working modes. Among them, the single electrode mode TENGs with no moving parts could facilitate the development of innovative sustainable energy harvesting technologies. Here, a polytetrafluoroethylene (PTFE)-copper (PC-TENG) tube with single electrode mode is developed for harvesting flowing water energy. Using tap water as a source, the PC-TENG tube, with a length of 40 cm and a diameter of 10 mm achieves a maximum power of 45 µW at a load resistance (R_L) of 5 MΩ. The sustainable power generation is demonstrated by powering light emitting diodes (LEDs) and a scientific calculator with tap water flowing at a rate of 2.5 L min⁻¹. Finally, the practical feasibilities of the proposed PC-TENG are demonstrated as self-powered sensor in two biomedical applications such as continuous wireless monitoring of IV drips injection, cardiac cycle and heart rate using a phantom. This work has great potential for the development of single electrode TENGs for continuous power generation and self-powered sensor applications.