Fig. 3. The effects of the thickness of the calcium alginate film and the concentration of the sodium alginate solution on the electrical output characteristics. (a) The measured open-circuit voltage, short-circuit current, and transferred charge of the fabricated TENG as the thickness of the calcium alginate film varies from 50 to 350 μm with the concentration of the sodium alginate solution of 2%. (b) The measured open-circuit voltage, short-circuit current, and transferred charge of the fabricated TENG as the concentration of the sodium alginate solution varies from 0.5 to 2.5% with the weight of the sodium alginate solution of 11 g. (c) Charging different capacitors by the fabricated TENG with the thickness of the calcium alginate film of 100 μm and the concentration of the sodium alginate solution of 0.5%. (d) An image of green LEDs powered by the TENG.