TENGs under the soles. (a) Structure sketch of the TENG tubes. (b) Photograph showing TENG tubes in diameter of 2–3 mm weaved into textile. (c) Working mechanism of the TENG. (d) Image of the “energy-shoe.” (e) An electronic watch is driven by the textile TENG. (f) A LIB is charged simultaneously by the “energy-shoe” while walking. Reproduced with permission from [133
]. Copyright Springer Nature, 2016. (g) Simplified structure and working mechanism of the TENG. (h) Top view of an as-fabricated TENG. (i) Short-circuit current in short circuit mode of the TENG. (j) Voltage of the storage capacitor (1 μ
F) versus time under different press forces with a constant frequency of 5 Hz. (k) Output voltage of the capacitor with full-wave rectifier. Reproduced with permission from [175
]. Copyright Elsevier, 2018.