Fig. 4
From: Deformable devices with integrated functional nanomaterials for wearable electronics
Wearable devices with performance-enhancing nanomaterials. a Photographs showing a transparent wearable motion sensor based on a GP heterostructure and the wearable electrotactile stimulator mounted onto human skin. b Schematic exploded structure of the transparent wearable motion sensor (left) and electrotactile stimulator (right). c Output current (left) and voltage (right) of the wearable motion sensor consisting of PLA (blue) and PLA/SWNTs (red) according to the bending and relaxing motions of the device. d Sheet resistance of pristine GP (red), GP doped with an AuCl3 solution (green), an AgNW/GP composite (blue), and its SEM image (inset). e Minimum required current for the wearer to sense stimulation with respect to the stimulation frequency. (a–e Reproduced with permission from Ref. [1], © 2015, WILEY–VCH Verlag GmbH & Co. KGaA, Weinheim). f Schematics of a semitransparent piezoelectric strain sensor, resistive sensor, and photograph of their applied form on skin (inset). g, h Schematics of g, the wearable piezoelectric strain sensor and h resistive temperature sensor. i X-ray photoelectron spectroscopy results obtained from a ZnO nanomembrane (top) and ZnO/SWNT composite (bottom). j Output voltage of the piezoelectric strain sensor consisting of ZnO (black), Cr/ZnO (red), and Cr/ZnO/SWNT (blue) for repetitive bending and relaxing of the sensor. k EC − EF of the AZO nanomembrane with different concentrations of AgNPs. l Relative change in the resistance of various types of temperature sensors with respect to temperature. (f–l Reproduced with permission from Ref. [46], © 2015, WILEY–VCH Verlag GmbH & Co. KGaA, Weinheim)