Gas Sensors Intelligent Test Systems And Portable Alcohol Tester

The intelligent gas detect system, based on gas sensor array and pattern recognition technique has promising applications in military, food industry, environment inspection. And it has become the research focus of the gas sensing technology in the last few years. In this dissertation, the gas sensor array testing system and the portable alcohol detector were studied.The gas sensor array testing system comprises the automated flow-injection apparatus, the data acquisition device and the PC software. Sample injection and data acquisition are realized automatically through real time PC control. Thereby it assures the reproducibility and reliability of testing. As the key of the sample injection, a digital control instrument of mass flow controller(MFC), which can work in online and offline mode, was designed. It can give 4 flow signals accurately at the same time. The concentration and flux of the sample gas can be set by the instrument software. The PC software with a friendly interface, written in VC++, can process and display data in real time. It controls the system through PLC (Programmable Logical Controller). Hence the system can realize some complex testing operations. In addition, as the hardware platform of electronic nose, the system can be used to develop researches such as pattern recognition algorithm and others. It has shown good performance in the studies of novel micro gas sensor array and electronic nose.A portable intelligent alcohol detector was designed. The detector, with LCD display, USB interface and battery supply, shows good characteristics in its small size, low power consumption and high accuracy. The hardware of the detector consists of a metal oxide micro gas sensor array, gas sampling apparatus and a signal processing unit with high speed SOC microprocessor. The low power chips were used to insure that the whole system power is under 1.5W. A feature extraction and B-P neural networks algorithm embedded in the single chip processor were presented in order to avoid large amount of computation. The alcohol detector performs well against disturbance of gasoline and perfume.