Modeling on oxygen chemisorption-induced noise in metallic oxide gas sensors

Noise spectroscopy might be highly useful for improving gas sensors selectivity if both theoretical model and sensing devices can be adequately developed. In this paper, we propose, as a first step towards an overall model, a theoretical description of adsorption-desorption noise in metal oxide gas sensors. Using Langmuir's isotherm, we derive an exact expression for the adsorption-desorption noise in the case where only one molecular species reacts on the sensor surface. We found that the contribution of adsorption-desorption noise to the noise spectra is a Lorentzian component. Application of the proposed model for simulating the oxygen chemisorption-induced noise is described. The validity of the proposed method, its limitations, and directions for its elaboration to more general cases such as gas mixtures are discussed in conclusion.