Research On A Wireless Surface Acoustic Wave Quality Sensor

Due to the rapid development of surface acoustic wave and semiconductor technology,the wireless surface wave sensor has the characteristics of non contact,fast,no power,anti-interference,easy coding,good confidentiality and low cost,and more and more surface acoustic wave devices are used in all kinds of bad,closed or toxic environment.The surface acoustic wave mass sensor for the measurement of micro mass is the foundation of surface acoustic wave gas sensor.On the basis of the theory of acoustic surface wave,this paper introduces the function model,impulse response model and equivalent circuit model of the interdigital transducer,and uses the improved function model to model and simulate the structure of the new structure of the interdigital transducer,and uses multiple couplers to reduce the two order effect of the device.On the basis of the YZ lithium niobate as a piezoelectric substrate,the best parameters of the new IDT structure,the length of the delay line and the size of the mass load area are determined.The frequency response of the combined sound path of the device is simulated on the MATLAB platform.The working center frequency of the wireless surface acoustic wave mass sensor is 109 MHZ,the insertion loss is about 8.3dB,the bandwidth is 7dB,the sidelobe suppression is 35 dB,the sensitivity reaches 44.084 KHz/ug.It has a good working range and the sidelobe suppression performance for the general rule type devices.Then the thickness of the film is measured and the electricity is measured.The effect of conductivity and ambient temperature on the device.At last,due to the high stability frequency coefficient of the piezoelectric substrate,the structure of the double sound circuit is used to compensate the error caused by the temperature.The corresponding back end conditioning circuit is designed.The modulation circuit is designed and simulated on the multsim platform.Finally,the ZigBee wireless transmission module is selected to transmit the signal to the device in wireless transmission.