Fig. 2. Energy-harvesting principle and electrical characterization of the degradable TENG. (a) Working principle of the TENG. (b) The open-circuit voltage, (c) short-circuit current, and (d) transferred charge of the fabricated TENG. (e) The relationship between the output voltage/current and the resistance to an external resistive load. (f) The relationship between the instantaneous power and the resistance to the external resistive load. The maximum instantaneous power is received about 9.5 μW when the external load is 20 MΩ. (g) The mechanical durability test of the TENG, where the open-circuit voltage is determined for 2000 cycles.