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Development of a Mid-Infrared Methane and Carbon Dioxide Dual-Gas Sensor System

A mid-infrared methane and carbon dioxide dual-gas sensor system is developed herein to realize the integrated measurement of methane and carbon dioxide A dual LED-PD light-emitting diode-photodiode optical-measurement structure with two narrow-band mid-infrared light-emitting diodes as the light source for methane and carbon dioxide measurements and two photodiodes as the detector sensing elements are designed Furthermore the selection of spectral lines and optical devices pulse current modulation of double LED light source and the temperature compensation algorithm are studied The optical measurement structure is designed based on the infrared absorption spectrum characteristics of methane and carbon dioxide gas and the pulse current modulation timing algorithm of double light sources is completed by using the high-speed response characteristics of LED devices that is the current is driven by narrow pulse mode Based on the analysis of temperature experiment the temperature influence factors are obtained through the data preprocessing of median normalization and then the temperature compensation algorithm is obtained by linear fitting Experimental results indicate that the average power consumption of the sensor system is as low as 38 3 mW the minimum measurement error of methane is 0 06% volume fraction and the minimum measurement error of carbon dioxide is 0 05% volume fraction The system can satisfy the requirements of low power consumption and stable and reliable real-time measurement of methane and carbon dioxide concentrations in coal mine