Phenomenological Model for a Light-Activated Gas Sensor

Light activation has been demonstrated as an effective alternative to heating for enhancing the gas response in semiconductor gas sensors. Despite two decades of research, the mechanisms behind their responses remain a topic of discussion. However, experiments have consistently shown trends in sensor responses to varying light conditions and gas concentrations. Building on these qualitative observations, we propose a phenomenological model that quantitatively predicts resistance changes in these devices. This prediction relies on a set of parameters that can be experimentally determined in advance. Our model includes effects such as photoconductivity, dynamic gas response, irradiance influence on sensitivity, and baseline drift. Validation with experimental data shows that the model accurately predicts sensor behavior over short and long timescales.