Dual-gas detection based on high-performance spherical photoacoustic cells

In this paper, a new high-performance spherical acoustic resonator was developed with a quality factor of 170. A dual-frequency modulation photoacoustic spectroscopy (PAS) technique was demonstrated for multi-component gas detection. The acoustic mode characteristics of the SPAC were analyzed from theoretical derivation and finite element analysis (FEA) simulation. Methane (CH4) and water (H2O) were selected as the research objects to evaluate the performance of the PAS sensor. To normalize the influence of H2O on the CH4 energy relaxation rate, a theoretical model of the V-T relaxation and self-calibration of the sensing system was established. The Allan-Werle deviation shows that the minimum detection limit (MDL) of CH4 @ 1653.72 nm is 1.8 ppm and H2O@ 1391.67 nm is 1.4 ppm when the averaging time is 154 s and 225 s, respectively. The reported sensing technique has the advantages of high sensitivity, simple structure, and low cost, which can be easily modified for other multi-gas analyses.