Design And Realization Of Electronic Blood Pressure Monitor Based On Korotkoff Sound Method

With the improvement of living standards,people pay more and more attention to their own health.And as an important indicator of physical health,blood pressure is valued by more and more people.However,the awareness rate of is only 42.6%in more than 300 million existing hypertensive patients in China,and hypertension crowds began to advance in age.One of the reasons for this phenomenon is that the existing sphygmomanometer product is complex,expensive or questionable results.Therefore,the development of a simple operation,accurate measurement,portable,cost-effective electronic sphygmomanometer has important significance.To solve the problem,the electronic sphygmomanometer in the paper is designed and realized,which is based on the non-invasive blood pressure measurement "gold standard"-Korotkoff method.The major content of the thesis include:1).Design the hardware system with STM32F103ZET6 chip and develop the embedded software system:The modified electret microphone sensor is used to acquire the Korotkoff signal,and a special signal conditioning circuit is designed for the characteristics of the Korotkoff spectrum,which achieves the function of the signal amplification,filtering and A/D conversion.The gas pressure sensor module is used to collect the cuff pressure signal,which achieves the function of the cuff pressure signal amplification and A/D conversion.The determination of systolic blood pressure/diastolic pressure was completed by combining the algorithm of Korotkoff sound noise reduction and recognition.USB/Bluetooth communication is used to upload data,which achieves the further data analysis and management;The liquid crystal display module is used to display the state of system,which enables the display of the measurement results.2).Research on Korotkoff sound noise reduction algorithm:Through the study of various digital filtering algorithms,a FIR-based Korotkoff sound digital filtering algorithm is proposed and implemented in this paper.The algorithm achieves the maximum effect of Korotkoff sound noise reduction under the condition of limited microprocessor resources,the filtering effect of which is verified by simulation experiments well.3).Research on Korotkoff sound recognition algorithm:In view of the Korotkoff sound recognition,there is currently no literature in this field.And through the study of pulse signal extraction algorithms in other fields,a pulse signal extraction algorithm for moving window based on signal power is proposed and implemented in this paper.The algorithm can recognize the starting point and end point of the Korotkoff signal well and solve the problem that the waveform characteristics of different age are different,the recognition effect of which is verified by simulation experiments well.4).Experiments of Korotkoff sound processing part and prototype performance:Experiments are carried out for the Korotkoff sound processing part and the prototype performance,which verify the effect of the algorithm and hardware circuit well.Compared with the mercury sphygmomanometer,the blood pressure monitor has a high correlation with it(systolic blood pressure correlation coefficient is 0.9117,diastolic blood pressure correlation coefficient is 0.9523),high accuracy(systolic blood pressure difference average is 3.5 mmHg,the standard deviation is 2.58 mmHg,the mean diastolic pressure difference is 3.35 mmHg,the standard deviation is 1.6 mmHg),which meets the AAMI standard.