Single-Sensor Gas Discrimination and Quantification Based on Novel Temperature Modulation Method

In this study, we report the discrimination and quantification of gases by a single gas sensor based on a novel temperature modulation method, which we have proposed recently. The temperature modulation utilizes the waveform of the heater voltage of which amplitude and frequency periodically change. First, the parameters of the heater voltage were optimized to achieve accurate discrimination of gas quality. Five modulated waveforms were employed, and the conductance of the sensor was measured under exposure to three organic gases (acetone, ethanol, and butyl acetate) with various concentrations. After building data vectors based on the frequency spectra of the normalized sensor conductance, gas discrimination accuracy was evaluated based on principal component analysis (PCA). As a result, 100% discrimination accuracy of the gas species was achieved for the modulated waveform with the frequency and voltage ranges of 0 - 10 Hz and 0 - 1.4 V, respectively. Furthermore, the 1st principal component in PCA derived from the conductance before the normalization was found to increase monotonically with the flow rates for the gas exposure, suggesting that it is applicable to quantifying gas concentration. These results demonstrate the potential of our proposed method for the simultaneous discrimination and quantification of gases.