Systematic Optimization of NO₂ Detection Using Activated Carbon-Based Resistive Sensors

Gas sensors play a crucial role in detecting harmful environmental gases. This study focuses on optimizing a resistive sensing layer for nitrogen dioxide (NO 2 ) detection at room temperature (RT = 25 °C), based on commercial activated carbon (AC). NO 2 sensing was assessed over a dynamic concentration range from 1 to 20 ppm. The impact of cycle time, interdigitated electrode gap, NO 2 gas flow rate, synthetic air purge rate and saturation on sensor response was examined. NO 2 sensing proceeded by adsorption, facilitated by the porosity and high surface area of AC. Sensing capability is reversible, suggesting purely physical adsorption. A response limit close to 65% was observed at sensor saturation. This work highlights the potential of commercially available AC as a practical solution for environmental NO 2 monitoring, even in the absence of any additional chemical modification.