fig2

Figure 2. Cyclic performance evaluation of LF-TENG. (A) Working mechanism of LF-TENGs based on CS modes; (B) Representative voltage output of LF-TENGs based on CS modes; (C) Schematic diagram of mechanical tapping device used for the cyclic performance evaluation of LF-TENGs. The top layer (PTFE) is attached to a glass substrate fixed on the movable clamp, and the bottom layer (PMMA) is affixed to the vacuum chuck over a load-measuring unit. The voltage output was recorded by an oscilloscope; (D) Voltage output of LF-TENG as a function of separation gap (d = 2, 3, 4, and 5 mm) when the tapping frequency and force are fixed at 4 Hz and 6.3 N; (E) Voltage output of LF-TENG as a function of tapping frequency (1, 2, 3, and 4 Hz) at d = 5 mm and F = 6.3 N. CS: Contact-separation; LF-TENG: laminated flexible-triboelectric nanogenerator; PMMA: polymethyl methacrylate; PTFE: polytetrafluoroethylene.