UV-activated chemiresistive gas sensor response curve analysis for the fast measurement of toxic gases

Photo-activated chemiresistive sensors have introduced a considerable improvement among all gas sensor technologies. However, the major drawback of these gas sensors is the long response time, which limits the potential of such sensors in many applications where rapid measurement is required. In this work, we investigated the response curve slope for gas concentration measurement. Our aim was to significantly reduce the response time of the ultraviolet light-emitting diodes (UV-LED)-activated chemiresistive metal oxide semiconductor (MOS) gas sensors so that steady-state response times are no longer needed. As a model semiconductor, zinc oxide (ZnO) nanowires (NWs) were fabricated to detect different concentrations of nitrogen dioxide (NO2) at room temperature under UV radiation with a wavelength of 275 nm. The consistent slope measurement results and the reproducible correlation between the response curve slope and the NO2 concentration represented the slope as an indicator of the gas concentration. The results indicated relatively high steady-state responses of 0.36, 0.65, 1.15, and 1.51 to the 5, 10, 25, and 50 ppm concentrations of NO2, respectively.