Portable electronic nose based on carbon nanotube-SnO₂ gas sensors and its application for detection of methanol contamination in whiskeys

In this paper, a portable electronic nose (E-nose) based on hybrid carbon nanotube-SnO₂ gas sensors is described. The hybrid gas sensors were fabricated using electron beam (E-beam) evaporation by means of powder mixing. The instrument employs feature extraction techniques including integral and primary derivative, which lead to higher classification performance as compared to the classical features (ΔR and ΔR/R₀). It was shown that doping of carbon nanotube (CNT) improves the sensitivity of hybrid gas sensors, while quantity of CNT has a direct effect on the selectivity to volatile organic compounds, i.e., methanol (MeOH) and ethanol (EtOH). The real-world applications of this E-nose were also demonstrated. Based on the proposed methods, this instrument can monitor and classify 1 vol% of MeOH contamination in whiskeys.