Research On Vital Signs Detection Method Based On Acoustic Surface Wave Sensor Technology

In recent years,there have been many major natural disasters and mine accidents in China.These natural disasters and man-made accidents have left deep wounds to our people's lives and caused immeasurable losses to our country and people.However,there are still some shortcomings in the field of mine rescue for life detection devices on the market.Therefore,in view of the demand of life sign detection for mine rescue,this project studies and designs a life sign detection system using surface acoustic wave sensing technology.Firstly,this paper analyses the development of surface acoustic wave sensing technology and vital signs detection system at home and abroad.Through the research and comparison of several life detection methods,the overall scheme of vital signs detection based on surface acoustic wave sensing technology is determined.Surface acoustic wave(SAW)sensors are designed with different frequency characteristics under different gas conditions.The lithium tantalate is selected as the piezoelectric material of this project by testing the performance of surface acoustic wave sensors based on different piezoelectric materials.Different types of interdigital transducers are designed by simulation,and their performances are tested.Finally,the uniform type of interdigital transducer is selected.The parameters such as period,aperture and logarithm of electrodes are further designed.The performance of the transducer is checked by simulation software.The film is prepared by thermal evaporation and the pattern of the transducer is produced by 10-step photolithography.In view of the need to detect the concentration of methane and carbon dioxide,tin oxide and polyethyleneimine were selected as gas sensitive thin film materials.Gas sensitive thin films were prepared by lifting method,rotating coating method and later annealing process.The effect of each part was checked and packaged under the microscope.The sensor test showed that the performance of the developed sensor met the detection requirements.The overall design and research of the vital signs detection system are carried out.According to the requirement of life detection,this project is designed as a portable terminal and a receiving terminal.The SAW sensor is used to collect real-time data at the portable terminal.After signal conditioning,the data is sent out by the wireless transmission part.Receiver receives detection signal analysis and processing,and then displays it with touch screen.Touch screen software is compiled with MCGS and Labview is used to design human-computer interaction interface of host computer to display vital signs parameters.Finally,the system integration and debugging are completed.The system test shows that the whole device can detect the vital signs of the tested personnel in time and effectively.The results show that the output of the system is stable,and all the indicators meet the design requirements.