Fig. 19: Self-powered wearable devices and other applications.

a Schematic of a moisture-driven electric generator (MODEG) face mask designed for power supply and real-time breathing monitor(left). Voltage output of a 4 × 4 cm² MODEG integrated with a commercial FDA-licensed FFP2 face mask during individual breaths(center), and single output voltage at normal and exercise breathing conditions(right). Reproduced with permission from ref. ²⁴⁴. Copyright 2023, Wiley. b Schematic of the self-powered system based on MEG with the ion diffusion of the bionic MEG membrane(left), MEG membrane-driven biomedical applications(center), and the self-powered wearable system on the diaper(right). Reproduced with permission from ref. ²⁴². Copyright 2024, Elsevier. c Schematic of an F-TENG, with the components and static contact angle of the hydrophobic surface(top), and the schematic of the F-TENG for harvesting droplets on a rainy day(bottom). Reproduced with permission from ref. ¹⁷⁰. Copyright 2021, American Chemical Society. d Schematic of an underwater wireless multi-site human motion monitoring system based on bionic stretchable nanogenerator (BSNG)(top), and the volunteer swam in different strokes with BSNG (bottom). Reproduced with permission from ref. ³⁸⁹. Copyright 2019, Springer Nature. e Schematic of solid–liquid TENG using PTFE filtration membrane for energy harvesting and image of the PTFE membrane showing the wettability (top). Schematic of the solid–liquid TENGs array for cathodic protection of A3 carbon steel in 3.5 wt% NaCl solution and open circuit potential with and without PTFE-based TENGs(center) and the images of A3 carbon steel immersed in the solution for 1–3 h with and without PTFE-based TENGs(bottom). Reproduced with permission from ref. ³⁹². Copyright 2021, Elsevier. f Schematic of hydrogel-based MEG devices with E-PTFE film for underwater moisture harvesting (left) and images of self-powered underwater wearable MEGs(right). Reproduced with permission from ref. ²²⁴. Copyright 2024, Wiley. g Schematic and optical image of solar-water hybrid electricity generator with common-electrode (HEG-CEA)(left). Schematic of HEG-CEA at large-scale future application(center), and optical images on lighting up a 20 W bulb and an integrated sensor by HEG-CEA on droplet energy harvesting(right). Reproduced with permission from ref. ³⁹⁷. Copyright 2023, Elsevier.