Photoacoustic Spectroscopy Gas Sensing System Based on Streamlined Shunt Dual-Resonant Photoacoustic Cell

This article presents and experimentally validates a photoacoustic spectroscopy (PAS) gas-sensing system based on a streamlined flow-splitting dual-resonant photoacoustic cell (SSDR-PAC) for the simultaneous detection of two-component gases. To mitigate issues such as flow field disturbances and interchannel inconsistencies inherent in traditional multiresonant photoacoustic cells (PACs), a streamlined flow-rectifying structure was introduced at the gas inlet. This design enables symmetrical gas distribution into two resonant cavities of differing dimensions, thereby establishing a dual-channel photoacoustic detection architecture with independent acoustic responses. Numerical simulations using COMSOL multiphysics indicate that the resonant frequencies of the two resonant cavities are 3846 and 4582 Hz, respectively. Furthermore, compared to conventional designs, the rectifying structure reduces the flow velocity at the resonant cavity inlets by more than 30-fold, effectively suppressing flow-induced noise and creating a low-disturbance acoustic environment within the resonant cavities. A dual-gas PAS detection system based on the SSDR-PAC was subsequently constructed, and experiments were conducted to simultaneously detect acetylene (C₂H₂) and methane (CH₄). With an internal cell volume of only approximately 4 mL, the system achieved minimum detection limits (MDLs) of 159 ppb for C₂H₂ and 184 ppb for CH₄, demonstrating an excellent balance between miniaturization and high sensitivity. The results indicate that the synergistic optimization of flow field distribution and multicavity acoustic structures enables stable, high-performance binary gas detection within a compact footprint, offering a promising new approach for the design of miniaturized multicomponent PAS gas sensing systems.