Light-Activated ZnO Sensor for NO₂ Detection at Room Temperature

Nitrogen dioxide (NO₂) is a pollutant gas that causes deterioration of the air quality. This work provides a promising approach to efficiently detecting NO₂ at room temperature using a chemiresistive sensor based on a zinc oxide (ZnO) ink on top of an interdigitated electrode (IDE). We propose a high-performance and low-cost gas sensor composed of aluminum electrodes printed on a flexible substrate using thermal printing. Unlike other gas sensors, the ZnO-based sensor works under ambient conditions and artificial light from fluorescent lamps, with no need for a dedicated light source. Changes in the sensor resistance are measured for low concentrations of NO₂ gas adsorbed on the ZnO surface, showing a linear increase in resistance when the concentration of NO₂ increases from 0.1 to 1 ppm. The advantages of this sensor are high sensitivity, fast response time, full recovery, good selectivity, stability over time, low power consumption and low cost.