Non-contact Respiratory Rate And Heart Rate Signal Detection System

The human heart,which is closely related to the health,is an important organ in the circulatory system.With the development of society and the advancement of science and technology,more and more people pay attention to the personal health problems,so the demand for daily physiological condition monitoring equipment is increasing.According to statistics from the National Health and Family Planning Commission of China(NHFPC),the mortality rate of cardiovascular diseases is much higher than other diseases such as tumors.As a result,it is necessary to control the mortality of diseased groups through primary prevention and secondary prevention.However,the monitoring techniques in the current prevention processes are more bound to the patients,and it directly affect the patients' experience and the treatment effects.Therefore,there is a need for an unobtrusive detection system to achieve cardiac monitoring of a patient.Moreover,the population ageing is a major problem in the process of social development.As the pressure of social pension continues to grow,the demand for testing and monitoring equipment required for family pensions is also increasing.Based on the research of Ballistocardiogram signal,this paper illustrates the design of a non-contact breathing and heart rate signal detection system,and the accomplishment of the system design,system electromagnetic compatibility test analysis,system measurement accuracy evaluation and so on.The detailed research contents are as follows:(1)System designGuided by the system requirements,a non-contact respiratory and heart rate signal detection system was designed.Firstly,through the literature analytical method,the physiological basis and mechanical characteristics of the ballistocardiogram signal were explored.Based on the principle of piezoelectric effect,the piezoelectric ceramic sensor with high stability and high sensitivity is selected to collect the ballistocardiogram signal,and an array layout methodology is used to extend the effective detection range of the sensor.Secondly the signal collected by the sensor is denoised,amplified and digitized to obtain a ballistocardiogram signal.The respiratory signal is extracted by the ballistocardiogram with smooth filtering and the respiratory rate is obtained by Fast Fourier Transform.A bandpass filter is used to filter out respiratory envelope and high frequency interference of ballistocardiogram signal.After the interference is filtered out,the heart rate is calculated by the J-wave peak measurement.Finally,a lower computer system is designed to control each functional unit for signal acquisition and data transmission,realizing the complete signal detection system.(2)System electromagnetic compatibility test and analysisAccording to the requirements of the electromagnetic compatibility safety test standard YY 0505-2012 for medical electrical equipment,the electromagnetic compatibility testing and the analysis of the designed non-contact respiratory and heart rate signal detection system were carried out.By optimizing the structure of the equipment,replacing key components,designing the interface protection circuit,etc.,the unqualified part of the test is optimized and the electrostatic discharge immunity performance of the system is improved.(3)System measurement accuracy assessmentA comparative test was designed.Using the standard detection device-MP150 system(BIOPAC)and the designed signal detection system to simultaneously detect the patient's breathing and heart rate status,then record the test results.The error rate analysis and Bland-Altman plot analysis were performed on the synchronous detection results to evaluate the measurement accuracy of the design system.The final error rate analysis showed that the designed detection system had a respiratory error rate of less than 4.5% and a heart rate error rate of less than 9.7%,meeting the requirements of the ECG monitoring standard YY 1079-2008.The Bland-Altman plot analysis results show that the heart rate test results of the designed system are in good agreement with the standard system.