Fig. 2
From: Inkjet-printed CMOS-integrated graphene–metal oxide sensors for breath analysis
Response curves for ZnO, ZG-3, ZG-6 in isothermal mode (300 \({}^{\circ }{\rm{C}}\)). a Illustration of sensing mechanism on detection of pure \({{\rm{NH}}}_{3}\) with graphene–ZnO composite in ISO mode; band diagrams at the graphene/ZnO and ZnO/ZnO interfaces shown on the right, \(\Delta V\) arises as \({{\rm{NH}}}_{3}\) adsorbs, resulting in enlarged depletion region. b Resistance response at 10, 4, 2 ppm of \({{\rm{NH}}}_{3}\), respectively. The orange region represents injection of \({{\rm{NH}}}_{3}\) in ppm. c Responsivity as a function of \({{\rm{NH}}}_{3}\) concentration with linear fits. d Resistance response at 10 ppm \({{\rm{NH}}}_{3}\) repeated over three cycles
