Graphical characterization of infrared absorption spectroscopic gas sensor using symmetrized dot pattern

A near-infrared gas sensor system was developed for methane (CH4) detection using symmetrized dot pattern (SDP) technique to transform the time waveforms from infrared absorption spectroscopy (IAS) into visible graphs. The basic principle of IAS was illustrated, and infrared absorption signals under different concentration levels were simulated based on the HITRAN (HIgh-resolution TRANsmission) database and LabVIEW software. For improving the detection sensitivity of SDP in the IAS system, the equations of SDP were updated by using a maximum detection value for normalization. The maximum detection value of the system was selected to normalize the radius and angles of SDP for increasing the resolution of the detection system. Graphs clearly show different trends under different concentration levels. Experimental tests on four CH4 samples at 40, 60, 80, and 100 ppm were carried out and SDP graphs were depicted. Through calibration experiment, the linearity between the maximum polar radius of IAS signals peak converted by SDP and the CH4 concentration reached 0.9888, and the detection limit of the system reached 67.41 part per billion (ppb).

Automated summary

This article presents a near-infrared gas sensor system that uses symmetrized dot pattern (SDP) technique to transform the time waveforms from infrared absorption spectroscopy (IAS) into visible graphs for methane detection. By updating the SDP equations with the maximum detection value, the detection sensitivity of the system is improved.