CH4, C2H6, and C2H4 Multi-Gas Sensing Based on Mid-Infrared Spectroscopy and SVM Algorithm

A multi-gas sensing system based on mid-infrared spectral absorption was developed for the detection of CH₄, C₂H₆, and C₂H₄. The system utilized a broadband infrared source, a hollow waveguide (HWG) absorption cell, and a tunable Fabry-Pérot (FP) detector. The limits of detection (LODs) of CH₄, C₂H₆, and C₂H₄ were 7.33 ppm, 2.13 ppm, and 8.09 ppm, respectively. For multi-gas measurements, the support vector machine (SVM) algorithm model was employed to calculate the concentration of each component. The root mean square error of prediction (RMSEP) values for CH₄, C₂H₆, and C₂H₄ were 15.91 ppm (1.26%), 1.64 ppm (0.57%), and 6.95 ppm (0.55%), respectively. The generation of stimulated absorption spectra of mixed gases was realized, and the sample selection of measurement for accurate concentration calculation of each gas was optimized. The system proposed in this work provides a simple, miniaturized, and cost-effective solution for multi-gas sensing.