Ultra-Low Frequency Acoustic-Flux Sensor for Efficient Gas Sensing

Abstract:
We present a novel low-frequency photoacoustic (PA) gas sensing approach based on a MEMS acoustic-flux sensor, overcoming the infrasound sensitivity limitations of conventional MEMS microphones. The sensor’s thermal detection principle enables efficient operation below 10 Hz, where high-power infrared emitters exhibit superior modulation performance, but standard microphones suffer reduced response. Integrated into an indirect PA system, a CO2 detection resolution of 50 ppm is achieved. Measurements also reveal a linear signal dependence on both gas concentration and temperature. This work demonstrates, for the first time, the effective use of an acoustic-flux sensor in PA gas detection, providing a pathway toward highly sensitive, compact, and cost-effective non-resonant PA systems. The results open new opportunities for miniaturized, robust sensors suitable for diverse industrial and environmental monitoring applications.