Multi-MEMS-microphone schemes in a miniature photoacoustic cell for acetylene trace gas measurement.

Dissolved gas analysis is a strong tool for online health monitoring of electrical power equipment. The industry's large-scale deployment of photoacoustic (PA) sensors is still constrained by cost and sensitivity, despite the great accuracy achieved with a mid-infrared light source or optical sensors. We provide a low-cost PA sensor for ppb-level trace gas sensing based on a near-infrared distributed feedback laser source, miniature gas cell, and multiple microelectromechanical system (MEMS) microphones. Five multi-MEMS-microphones schemes are modeled. The simulation indicates that the sensor, including two MEMS microphones in the center of the resonator, is the most cost-efficient option. The experiments that present this scheme can be realized easily by modifying a traditional single microphone PA cell and with ppb-level sensitivity.