Research On Pulmonary Sound Monitoring Device Based On PZT Piezoelectric Sensor

Emphysema disease is one of the most important causes of health threats and deaths in humans,and lung sound signals,as a typical basis for reflecting lung abnormalities,are of great importance in performing emphysema disease diagnosis.In order to make up for the shortcomings of traditional auscultation methods,this paper develops a new lung sound monitoring device with low cost,good performance,stability and reliability,using the piezoelectric effect oriented to the lung sound auscultation application,and the targeted design and optimization of the overall structure of the device,the conversion from acoustic to electrical signals enables patients to easily collect,summarize and process acoustic diagnosis and treatment information to achieve early detection and treatment of lung diseases.The main work of this paper is.（1）Combined with the corresponding basic theoretical analysis,the sensing method and the type of sensitive element of the device are clarified.On the basis of ensuring the miniaturization of the sensor structure,the optimal dimensional parameters of the sensitive element and housing structure are determined by ANSYS software simulation,and the output sensitivity and frequency response characteristics of the sensor are improved so that it can meet the demand of target signal acquisition in the frequency band of 100-800 Hz.（2）Analyze the noise propagation paths existing in the auscultation process,develop corresponding reasonable mechanical solutions for different types of noise,determine the way of auscultation diaphragm superimposed on soft silicone rubber as the optimal sound transmission medium,and complete the overall structural design of the sensor.Finally,the corresponding signal conditioning circuit was built for the sensor output signal and frequency response characteristic curve encapsulated inside the structure housing to ensure the portability of the device.（3）Performance evaluation tests were conducted on the device as a whole.The results show that the sensitivity of the lung sound monitoring device designed in this paper is 5.63 V/g and the signal-to-noise ratio is 13 d B.By comparing the output signal with the existing electronic stethoscope,it can be seen that the device shows good performance advantages in lung sound acquisition and can meet the overall performance requirements of the device.