In this work, we studied the influence of cross-interference effects between VOCs and NO on the performance of SnO2and Pt-SnO2-based gas sensors. Sensing films were fabricated by screen printing. The results show that the response of the SnO2sensors to NO under air is higher than that of Pt-SnO2, but the response to VOCs is lower than that of Pt-SnO2. The Pt-SnO2sensor was significantly more responsive to VOCs in the NO background than in air. In the traditional single-component gas test, the pure SnO2sensor showed good selectivity to VOCs and NO at 300 °C and 150 °C, respectively. Loading noble metal Pt improved the sensitivity to VOCs at high temperature, but also significantly increased the interference to NO sensitivity at low temperature. The explanation for this phenomenon is that the noble metal Pt can catalyze the reaction between NO and VOCs to generate more O−, which further promotes the adsorption of VOCs. Therefore, selectivity cannot be simply determined by single-component gas testing alone. Mutual interference between mixed gases needs to be taken into account.
Drunk driving is a major threat to global traffic safety, accounting for 50% to 60% of traffic accidents. To address the bottleneck problem of insufficient selectivity of metal oxide gas sensors in drunk driving detection, this paper proposes an optimization strategy based on the principle of selective extraction and programmed temperature desorption technology. This strategy uses temperature modulation to control the adsorption processes of target gases, solving the cross-interference problem between ethanol and other volatile organic compounds in exhaled breath. A temperature-modulated on-chip programmed temperature desorption ethanol sensor was developed using ZSM-5 and Pt@SnO2 as the adsorption and desorption material and gas-sensitive material for ethanol, respectively. By optimizing the temperature modulation parameters (heating and cooling rates, adsorption time), the height of the ethanol desorption peak was precisely quantified. The maximum deviation of the desorption peak height of interfering gases and their mixtures with ethanol (40 ppm) in human exhaled breath from the detection instrument was only equivalent to 5.20 ppm ethanol. The highly selective ethanol sensor was integrated into the USB detection terminal to form a portable U-disk drunk driving detector, which has significantly better sensitivity and anti-interference ability than senior commercial products. The high selectivity is essentially due to the rapid extraction of ethanol from the environment by ZSM-5 in a short time.
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