Influence of Humidity and Different Gases on a Resistive Room Temperature NO 2 Gas Dosimeter Based on Al-Doped ZnO for ppb-Concentration Detection

Abstract

NO 2 in the ppb-range can be detected at room temperature by aluminum-doped zinc oxide, whereby the sensor devices are operated as resistive gas dosimeters. In this operation mode, the dose of an analyte is measured directly and the actual analyte concentration can be determined by mathematical differentiation. It is crucial that already adsorbed analyte species do not desorb from the sensitive material and therefore their recovery time is infinite. As classically operated metal oxide sensors are known for their low selectivity, the selectivity of the sensor is investigated. The here-presented results show that the sensor can detect NO 2 very selectively even at low concentrations in the low ppb range. Since it has already been reported that humidity can accelerate the desorption of gas molecules from metal oxides, furthermore, the influence of humidity on the dosimeter behavior is investigated. It is shown that the holding capability is negatively affected and the analyte desorbs faster in humid atmosphere.