A Noise Spectroscopy-Based Selective Gas Sensing with MOX Gas Sensors

We propose a new method for obtaining a fluctuation-enhanced sensing (FES) signature of a gas using a single metal oxide (MOX) gas micro sensor. Starting from our model of adsorption–desorption (A–D) noise previously developed, we show theoretically that the product of frequency by the power spectrum density (PSD) of the gas sensing layer resistance fluctuations often has a maximum which is characteristic of the gas. This property was experimentally confirmed in the case of the detection of NO2and O3using a WO3sensing layer. This method could be useful for classifying gases. Furthermore, our noise measurements confirm our previous model showing that PSD of the A–Dnoise in MOX gas sensor is a combination of Lorentzians having a low frequency magnitude and a cut-off frequency which depends on the nature of the detected gas.