Fig. 2. Electrical characteristics of the TENG sensors.

a Platform with adjustable pressing force and frequency consists of a linear motor, ergometer and sensor. b, c The open-circuit voltage and short-circuit current obtained by pressing the sensor at 1 Hz frequency with different forces (from 1 N to 5 N). Inset: schematic diagram of the sensor size. d, e The open-circuit voltage and short-circuit current output of the sensor at the pressing frequency (from 1 Hz to 5 Hz) with a force of 5 N. f, g Open-circuit voltage and short-circuit current output obtained from sensors with different areas at a frequency of 1 Hz with a force of 5 N. h, i The open-circuit voltage and short-circuit current output obtained from sensors with different thicknesses at a frequency of 1 Hz with a force of 5 N. j The open-circuit voltage for two sensors placed in series and in parallel. k The maximum output power and maximum voltage curves for the triboelectric sensor used as a power supply with different external load resistances (ranging from 10⁷ to 10¹¹ Ω) with a force of 5 N at a frequency of 2 Hz. l Mechanical durability test for up to 2000 press-release cycles. Inset: the voltage signals generated for the initial 10 s and the final 10 s.