The Research Of System Integratd Technology Of Surface Acoustic Wave Gas Sensor

The gas detection technology had became extremely important,for the chemical warfare agents on the battlefield and industrial toxic gas had does enormous harm to the human body. Surface acoustic wave devices, which are widely used in military and commercial equipments, have an overwhelming superiority in gas detection. This topic is produced in this background, in the dissertation, a gas detection system based on SAW devices is investigated.A SAW sensor array was manufactured using three SAW devices, in which each sensor was coated with a different sensitive layer, respectively. And then combining the pattern recognition algorithm,test and analyz gases response in different concentrations, finally the detection can realize the classification of nerve gas simulant(DMMP), mustard gas simulants(2-CEES) and interfering gases, showing the gas type and its concentration.The content of this dissertation is divided into three parts:The first part is the design for SAW sensor’ application.Investigation in hardware consists of the design of SAW sensor oscillation circuit, core circuit based on dsPIC, thermostat circuits based on TEC, heating circuit through PID control algorithm,power supply module, display module,pneumatic driving module and data storage module and the analysis of the peripheral circuits. Based on the investigation of hardware, the front-end program for control is designed, including PID control algorithm and data storage based on the theory of I2 C interface circuits. Then, response of sensors in different conditons, which is influenced by gas density, temperature, and gas-preconcentrator is tested and analyzed.The second part is the process of data from SAW sensors.Investigation in hardware of back-end of the system consists of acquisition, transport and storage of signal of SAW sensors,and the power consumption consisting of power supply module, display module, pneumatic and gas-preconcentrator driving module, and temperate control module has calculated and analyzed. Based on the investigation of hardware, study the processing of data from integrated gas sensor of BP neural network algorithm, and through the MATLAB simulation platform to achieve.The third part is that hardware and software is tested based on the detection systems, On this basis, gas mimetic and gas simulant were tested and analyzed systematically.finally,the dection can recognize the gas type and its concentration.The study of the detection systems of integrated gas sensors based on SAW technology including hardware, software and related algorithms ends up with a reliable PCB circuit which could be used to validate the hardware, software and concerned algorithm and paves the way for the development of practical detection system based on SAW gas sensors.