Development and Performance Analysis of a Portable NOx Gas Sensor for Environmental Monitoring Applications

This paper presents the development, optimization, and performance analysis of a portable NOx gas sensor for environmental monitoring applications using LiMnFeO4 as the sensing material. Metal oxide semiconductors have gained wide attention in gas sensor research, particularly for applications such as breath analyzers. In this study, we investigate the material properties of LiMnFeO4 sensing layer for the detection of NOx gas. By theoretical analysis, a proportional trend is observed between change in resistance of sensing layer and concentration of target gas. In addition, a heating layer, supporting layer enhancing the sensing phenomena of gas sensor, is designed and simulated in COMSOL Multiphysics and the trend between applied voltage and temperature rise is observed. With increase in applied voltage from 0.5 V to 5 V, a temperature rises of 130 % (300 K to 690 K) is obtained from numerical simulation of heating layer. Moreover, a mathematical model that connects the relationship between the gas concentration and the rate of change of resistance is addressed. Our work will aid researchers in defining and predicting the behavior of gas sensors, and our findings have potential applications in environmental monitoring systems.