Design and Simulation of Gas Cell for Mid-IR Trace Multi-Gas Sensing using Photoacoustic Spectroscopy

A design and simulation of a gas cell to be used for mid-infrared photoacoustic (PA) trace multi-gas sensing for environmental pollution monitoring is presented. For the operation of the cell at its resonant frequency, to obtain maximum amplitude of the PA signal, it is necessary to modulate the incident light at the cell's resonant frequency. This fundamental resonance frequency and the optimum position of the PA detector to be placed on the surface of the cell have been simulated using COMSOL Multiphysics for Nitrogen gas since resonant frequency will depend on the gas with maximum concentration and nitrogen has maximum concentration in air. The scope is to develop a compact sensor design for which the total volume of the cell is kept less than 10 cc which is well within the fabrication limitations as well.