Research On Fast Response Dual-channel Gas Sensor Based On NDIR Principle

In recent years,with the rapid development of the national economy and the improvement of people’s living standards,the CO₂content in the atmosphere has increased year by year,and the environmental problems faced by our country have become more and more serious.Therefore,in order to meet the safety requirements of underground production and ensure the safety of underground construction workers,it is particularly important to design a CO₂sensor with high sensitivity,large range,miniaturization,excellent stability and good environmental adaptability.This paper compares and analyzes the advantages and disadvantages of various gas detection methods according to various gas concentration detection instruments on the market,and finally uses the infrared absorption spectrum of gas molecules with characteristic wavelengths to design a complete non-spectroscopic infrared CO₂sensor system.Including sensor design and supporting host computer.First,the infrared thermal radiation light source HSL5-1115 and the pyroelectric infrared detector PYS3228 are used,and the selected light source and detector are tested to select the appropriate chopping frequency.Design a miniature foldable optical air chamber,complete the 3D design of the air chamber through Solid Work,and use the Trace Pro optical software to perform optical simulation of its reflection characteristics and light intensity distribution characteristics.Secondly,according to the optical gas chamber designed by the combination of the selected light source and the detector,the light source driving circuit,the narrow band-pass filter and amplifier circuit,the power supply design,the STM32 core circuit of the single-chip microcomputer and the temperature acquisition circuit are designed to effectively realize the reading of the output signal of the detector.out.And make circuit boards,and complete the welding and debugging of each module circuit through laboratory instruments.Again,complete the microcontroller program design,including light source driving and ADC sampling.And through median filtering and mean filtering to remove large-amplitude pulse interference and small-amplitude high-frequency noise,to achieve peak-to-peak RMS sampling.Using Lab VIEW to write the host computer software,it has the functions of real-time data acquisition and waveform display,data storage and readout functions,and data security and confidentiality functions.Finally,through the calibration experiment in the high and low temperature humidity box,the temperature compensation function of the sensor is explored,the concentration calculation formula of the designed sensor is determined,and the performance of the sensor is tested.The experimental data show that the sensor can achieve accurate measurement within 0-40℃through temperature compensation.Between 0-2%,the measurement error is less than 0.1%;between 2%-5%,the measurement error is less than 0.25%;basically meet the needs of industrial production and happy life.In this subject,the NDIR dual-channel pyroelectric CO₂sensor designed to meet the real-time monitoring of CO₂gas concentration in a certain environment has reference value for the subsequent research on gas sensors.