fig5

Figure 5. Different signal output forms. (A) Potentiometric measurement for continuous, wireless monitoring. This figure is quoted with permission from The American Chemical Society^[58]; (B) Resistance measurement suited for gas molecules detection. This figure is quoted with permission from The American Chemical Society^[59]; (C) Spike signals can classify different ingredients under humidity disturbance conditions. This figure is quoted with permission from The American Association for the Advancement of Science^[60]; (D) Non-electrochemical signals contribute to the development of sensitive materials. This figure is quoted with permission from The John Wiley and Sons^[61]. LED: Light-emitting diode; OTS: ovonic threshold switch.