Fig. 5. The structure and electrical output characteristics of the designed TENG for harvesting water wave energy. (a) The device structure of the designed TENG for harvesting water wave energy. (b) The image of the sealed TENGs floating on water and the optical images of LEDs driven by the water wave. (c) The measured open-circuit voltage and (d) the transferred charge of the fabricated TENG at different vibrational frequencies. (e) The relationship between the output characteristics of the designed TENG and the vibrational frequencies. (f) The measured open-circuit voltage and (g) the transferred charge of the fabricated TENG at different units. (h) The relationship between the output characteristics of the designed TENG and the unit number.