Research On The Test Technology Of Lamb Wave Multi-parameter Gas Sensor

Lamb wave sensor is an ultrasonic sensor based on Lamb wave and has broad industrial application prospects due to its advantages of high sensitivity,low loss and multi-mode characteristics.Recent studies have demonstrated that as the flow rate,humidity or temperature of the flowing gas changes,the center frequencies of Lamb wave sensor shift.However,there is no measuring instrument which can automatically obtain the center frequency of Lamb wave sensor.Experiments concerning Lamb wave sensor need to be implemented by network analyzers,which means that the measured results of measured parameters cannot be acquired automatically but by manual operation.This limits the applications of the Lamb wave multi-parameter gas sensor.In addition,a gas test device is required to obtain the measurement performance of Lamb wave sensor for the flow rate,humidity and temperature.However,existing gas regulators are mainly aimed at the temperature and humidity of the gas and unable to implement the independent regulation of the flow rate,humidity and temperature,which cannot meet the demands for the performance test of the Lamb wave multi-parameter gas sensor.In this dissertation,a special data acquisition instrument prototype was developed to automatically acquire the center frequencies of the Lamb wave multi-parameter gas sensor in multiple modes.In addition,a special gas test device was designed to provide a test platform of the flow rate,humidity and temperature for the Lamb wave multi-parameter gas sensor.The main contents and contributions of this dissertation are as follows:(1)A method for fast and automatically obtaining the information of the Lamb wave sensor was proposed by combining the frequency scanning technology with a peak fast search method.A frequency scanning source module,amplitude phase detection module and a control module were designed and a data acquisition instrument prototype was developed based on the proposed method.Experiments of the frequency scanning and the fast peak search for Lamb wave sensor were carried out in multiple modes by using the data acquisition instrument prototype.Experimental results show that the method and the prototype are effective.(2)A gas test device designed for the Lamb wave sensor was developed,including a flow rate module,a humidity module and a temperature module.The gas test device was controlled to obtain the adjustment capabilities of the flow rate,humidity and temperature.Experimental results show that the gas test device can implement the gas multi-parameter adjustment,and the test platform is effective.(3)Finally,by combining the data acquisition instrument prototype and the gas test device,the Lamb wave sensor was tested in different flow rate,humidity and temperature of the gas to verify the effectiveness of the Lamb wave multi-parameter gas sensor and the data acquisition instrument prototype.