A Dynamic Data Acquisition System For Array Gas Sensors Based On LabVIEW

In the latest twenty years, the research about gas sensors and electronic nose is the most active in the research area of sensors. Electronic nose is a kind of odor recognition system, which is based on the integrated gas sensor array and multi-sensor data fusion technology. And it will be widely used in different areas, such as food industry, medical diagnostic, environmental monitoring, customs inspection, etc.A complete electronic nose is comprised of two parts, the data acquisition system of gas sensors and the pattern recognition system. In this paper, we are devoted into the development and research of a data acquisition system of gas sensors, through which we can acquire and provide useful information to the pattern recognition system. The system can control the working temperature of the gas sensors, obtain the dynamic data through MCU-controlled data acquisition card, transfer these data to PC via RS232 cable, then display and store these data.The main contents of the thesis are summarized as following:1: Through the study of the theories about gas sensors and electronic nose, we finallydesign a data acquisition architecture based on LabVIEW technology, which canacquire the dynamic data from gas sensor array.2: Choose different gas sensors to comprise an integrated gas sensor array, and designits signal conditioning circuit.3: Fabricate a MCU-controlled data acquisition card, which has good performanceand can replace the commercial expensive card.4: Apply the PWM heating method, which uses modulated-voltage-pulse to heat thegas sensors. This method can supply more sufficient information, increase the data ofdynamic response and the dimensions of analyzed samples for gas recognition.5: On the PC platform, we use LabVIEW to develop a detection application program.The LabVIEW technology can be easily studied and save us a lot of time.The system can acquire 0～+5V voltage signals through 6 analog input channels with 12-bit resolution, and the sampling rate of every channel is about 200 Hz. Also, The system, which has low cost and good performance, has been tested and reflects easy operation, good stability and reliability.