Researches On Design Of Test Platform And Analytical Method For Gas Sensors And Electronic Noses

Gas sensor is a kind of device converting gas volume fraction(concentration)into measurable signals,and has wide application prospects in food safety,air quality,health and other fields.However,gas sensors usually are difficult to achieve responses only to one kind of gases.Therefore,the development and control method of new types of gas sensors have become research hotspots recently in this field,especially the gas sensor array and a variety of temperature modulation techniques based electronic nose systems,which have been widely studied for qualitative and quantitative detection of mixed gases.How to evaluate the performances of parameters of newly developed gas sensors and electronic noses,and to build an application-specific gas sensor response database as well as seeking their analysis methods,has been critical support of researches in this area.Therefore,combined with the demands of actual project practices,in order to adapt to the characteristics of variety of current new gas sensors and electronic nose systems,a test platform for gas sensors and electronic nose systems has been designed and implemented in this thesis,and corresponding analysis methods have been integrated.The study is to achieve a test platform with fast and accurate gas distribution module,test mode controllable and with typical analysis methods,which can provide a good test basis for the optimization of sensor array and their operating modes,and the evaluation of parameters of gas sensors and electronic nose systems.The whole test platform includes a gas distribution module,a sensor measurement and control interface,an acquisition module and a data analysis module.The gas distribution module is based on the dynamic volumetric method.Advanced mass flow controllers are selected,which can realize gas mixtures of 4 kinds of gases.And the gas concentration distribution type,gas types and total flow in the pipe are all adjustable.The sensor measurement and control module and data acquisition module can be used to test various types of sensors.The control interface circuit of metal oxide gas sensors is designed as they are the most popular sensor in current researches.Using the data acquisition card of NI company,heating control and real-time data acquisition of 16 sensors can be achieved.The working modes of sensors include two kinds,which are constant temperature mode and temperature modulation mode,and they are realized by the software control.The data analysis module is to analyze the real-time data collected for the purpose of obtaining the maximum sensor response value,response and recovery time,gas selectivity and other parameters.The module also adds the current pattern recognition methods including principal component analysis and typical neural networks in the field of electronic nose systems.Software system of the test platform is built based on NI LabView developing environment.The hardware and software system of the test platform has been constructed,which can realize the stable and dynamic control of 16 sensors and test of 4 kinds of gases.The sampling rate is up to 500KS/s.Through the comparison of gas distribution results,testing and calibration of parameters of sensors,the typical recognition results of mixed gases,measurement and calibration of new gas sensor and electronic nose systems can berealized.Good references can be provided for researches on improvement of gas sensor detection performance,measurement and controlling mode,gas mixture recognition and quantification of new electronic noses.