Interdigital electrode based triboelectric nanogenerator for effective energy harvesting from water

Despite high voltage output, the low current output of triboelectric nanogenerators (TENGs) limits their expansion into practical applications. The incorporation of additional machinery, such as transformers and gear trains, has been proposed to remove this bottleneck. Here, we report a simple and cost-effective strategy that employs a compact interdigital electrode (IDE) to increase the current output in TENG devices. A foldable, twistable, and rollable IDE-based TENG, comprised of finger-like aluminum electrodes sandwiched between polytetrafluoroethylene and polyester films, was fabricated to harvest triboelectric energy from water. This IDE-based TENG exhibited a triboelectric charge threefold higher than that of a single electrode-based TENG. Triboelectric charge is greatly enhanced when the width of the IDE is comparable to the size of the water droplet being harvested. Using a cone-shaped IDE-based TENG, we showed that the folding angle of the device and the water droplet volume rate are important for enhancing triboelectric currents. Using a cylinder-shaped IDE-based TENG, we demonstrated the powering of 10 light emitting diodes and the charging of a 0.1-μF capacitor to 15 V within 20 s.