A multi-gas sensing system was developed based on the detection principle of the non-dispersive infrared (NDIR) method, which used a broad-spectra light source, a tunable Fabry–Pérot (FP) filter detector, and a flexible low-loss infrared waveguide as an absorption cell. CH₄, C₂H₆, and CO₂ gases were detected by the system. The concentration of CO₂ could be detected directly, and the concentrations of CH₄ and C₂H₆ were detected using a PCA-BP neural network algorithm because of the interference of CH₄ and C₂H₆. The detection limits were achieved to be 2.59 ppm, 926 ppb, and 114 ppb for CH₄, C₂H₆, and CO₂ with an averaging time of 429 s, 462 s, and 297 s, respectively. The root mean square error of prediction (RMSEP) of CH₄ and C₂H₆ were 10.97 ppm and 2.00 ppm, respectively. The proposed system and method take full advantage of the multi-component gas measurement capability of the mid-infrared broadband source and achieve a compromise between performance and system cost.

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.