Miniaturized Resonant Infrared Photoacoustic Gas Sensor

It's a high selectivity, high sensitivity, high stability way that use photo acoustic method to detect trace gas concentrations. Around the goal of a MEMS photo-acoustic cell, this paper developed a highly sensitive miniaturized infrared photo-acoustic system.Developed a prototype of a highly sensitive miniaturized infrared photo-acoustic system, using one-dimensional vertical resonant mode resonator, quarter -wavelength sound filters and Brewster windows structure. The system is the high sensitivity, can detect even lower concentrations of 20ppb of ethylene gas.This article focuses on relationship between the photo-acoustic signals and the testing phase, and comparison of three different signal extracting method. analyzes the reason of the phase change in testing, and obtains conclusion that under a fixed phase delay using lock-in amplifier to detect photo-acoustic signals can get a high sensitivity. According to the research on the PA signal and phase change, proposed size requirements on the design of photo-acoustic cell.