Simultaneous detection of multiple gases using multi-resonance photoacoustic spectroscopy

In this paper, a gas sensing technique based on multi-resonance photoacoustic spectroscopy (M-PAS) is firstly proposed for simultaneous detection of multi-component gas molecules. To explore the capabilities of this technique, a spherical resonator with multiple resonant modes and high quality factors are detailedly developed by theoretical simulation and experimental analysis. The proposed M-PAS technique combing with wavelength modulation spectroscopy (WMS) is investigated for simultaneous detection of H2O, CO2 and CH4, respectively. Based on Allan-Werle deviation analysis, the detection limits of 1.17 ppm for H2O, 83 ppm for CO2 and 1.76 ppm for CH4, respectively, at the integration time of 136 s, 181 s and 195 s were achieved, corresponding to the normalized noise equivalent absorption (NNEA) coefficient of 6.03 × 10−10 cm−1W/√Hz, 5.46 × 10−10 cm−1W/√Hz, 2.36 × 10−9 cm−1W/√Hz. The reported sensing technique has potential applications in atmospheric environment monitoring, industrial process control and breath gas analysis by appropriate improvements, and can easily be modified for other multi-component gas analysis.