Figure 9.

(A) Structural configuration of Ecoflex/hydrogel/Ecoflex gel composite-based smart skin device. (B) Photograph of the smart skin containing nine hydrogel pixels on back of a hand. (C) Electric signals at different pixels for detection of pressure location. (D) Voltage signals of nine pixels with a “T” shaped acrylic plate placed on skin. (E) Mechanoluminescent intensity of skin at various pressure magnitudes. (F1–4) Photographs of a real-time tracking of ML signals by external force. (G) Photograph of smart skin to power LEDs to demonstrate energy-harvesting property. (H) Equivalent circuit of a self-charging system to power an electronic watch (I). Adapted with permission [27]; copyright 2019, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.