fig13

Figure 13. (A) Schematic illustration of the working principle of the wearable e-nose system; (B) photograph of a wearable e-nose on the armpit of a subject, with an integrated chemical sensor array and wireless circuit; and (C) responses of the sensor array to 5-25 ppm of hexanoic acid, dodecane, and decanal. This figure is quoted with permission from Zheng et al.^[126]. MCU: Micro-controller unit; PVDF: poly(vinylidene fluoride); VOCs: volatile organic compounds.