TENGs engineered into the insoles. (a) Schematic structure of the EHI. Inset: enlarged view of an inner structure of the designed insole. (b) Working principle of the energy harvesting insole (EHI). (c) Open-circuit voltage under various air volumes. (d) The durability and stability test results of the EHI after more than 10 000 cycles under the same working conditions. (e) Output voltage of the EHI before immersion and after immersion in water. Reproduced with permission from [131
]. Copyright Royal Society of Chemistry, 2019. (f) Schematic illustration of the pDA-S-TENG. (g) Output currents of the pDA-S-TENG when pressed by textile, nitrile film, and latex. (h) The shiny shoe driven by the pDA-S-TENG with insole size. (i) Accumulated voltage across a single capacitor charged by this pDA-S-TENG. Reproduced with permission from [166
]. Copyright Elsevier, 2018.