Development Of Data Acquisition System Based On Semiconductor Gas Sensor

In the laboratory environment,the detection methods of volatile organic compounds(VOC)include gas bag method,low-pressure gasification method and so on.These methods take a long time to collect and are easy to have residues,which leads to inaccurate experimental data.In this paper,the method of heating evaporation is used,volatile organic compounds can quickly volatilize and diffuse to the whole experimental device in high temperature environment,so as to solve the problems of slow volatilization,incomplete volatilization and uneven gas concentration.Semiconductor gas sensor array is used to improve the accuracy of VOC detection.At the same time,the volume of the gas experimental device is fixed,and the standard gas can be introduced to calibrate and calibrate the sensor,which provides a method and way for the performance detection of the sensor.This paper designs and makes a complete set of data acquisition system,which is mainly divided into three main parts: gas experimental device,hardware circuit and upper computer.The gas experimental device is designed by CAD and made of plexiglass.It contains evaporator platform,sensor interface platform and so on,which is used for gas collection and data collection.The hardware circuit is divided into front-end circuit and back-end circuit according to different functions.The main function is to convert the collected analog signal into digital signal and upload it to the upper computer for recognition and reception.The front-end circuit mainly includes the sensor heating and voltage reducing circuit,power supply circuit and R-V conversion circuit,Semiconductor gas sensor array is used to improve the accuracy of VOC detection,which is responsible for collecting the analog signal output by the sensor,converting the resistance signal of the sensor into voltage signal and outputting it through the R-V conversion circuit;the back-end circuit mainly takes ad7606 and STM32F103 as the core,converts the analog signal into digital signal,and transmits the data through the serial communication circuit To the upper computer processing.The upper computer is developed with C++ language and MFC framework under Visual Studio development platform to realize real-time data acquisition,display and storage.At the same time,the functions of real-time curve display,sensor sensitivity calculation,response recovery time calculation and liquid volume calculation corresponding to standard VOC gas concentration are also designed to feed back the collected data and the performance index of the sensor to users.This data acquisition system realizes the detection of volatile gas concentration of organic compounds by semiconductor gas sensor in the laboratory environment;realizes the calibration and performance detection of the sensor after configuring different concentrations of standard gas.