Ethanol and H2S gas detection in air and in reducing and oxidising ambience: application of pattern recognition to analyse the output from temperature-modulated nanoparticulate WO3 gas sensors

Ethanol and H2S, mixed with air or NO2, were detected using a novel nanocrystalline WO3 sensor produced by advanced gas deposition and operated in a dynamic mode effected by square voltage pulses applied to its heating element, thereby modulating the operating temperature between 150 and 250 °C. The sensor signals were decomposed by fast Fourier and discrete wavelet transforms, and the ensuing data were used as inputs into various pattern recognition methods for identification and quantification purposes. We were able to show that ethanol and H2S could be detected with good sensitivity and selectivity in the presence of both reducing and oxidizing gases.