Research On Cardiopulmonary Signals Detection System Based On Microcoil Eddy Current Effect

The mortality caused by cardiopulmonary diseases remains high because of the acceleration of social pace.The demand of people for cardiopulmonary signals detection rises continuously in daily life.Therefore,the non-contact cardiopulmonary signals detection technology based on traditional diagnosis technology of cardiopulmonary diseases is studied in this work.And abundant convenience has been brought by this technology.It has aroused the interest of many researchers at home and abroad because of its safety,non-invasive,simple implementation and portability.This thesis focuses on the research of portable magnetic induction cardiopulmonary signal detection system.The main research contents and innovations include:(1)Three different coil sensor models for measurement have been proposed after reviewing the development status of physiological signal detection based on electromagnetic induction.A double-coil detection scheme is proposed based on the magnetic induction phase shift(MIPS)technology.COMSOL simulations are performed to determine the best parameter and placement of the coil.(2)A set of portable cardiopulmonary signals detection system is established based on electromagnetic induction.The system is designed based on STM32,including sensor coils,phase detection circuit,data acquisition circuit,data storage and display circuit.And the software kit is compiled to realize the collection,storage and display of cardiopulmonary signals.The cardiopulmonary signals detection abilities of hard and flexible PCB mirco-coils have been tested under four different breathing states,respectively.The experimental results show that the flexible PCB mirco-coil has a better detection ability of the cardiopulmonary signals,which can also bring comfortableness.(3)The complete ensemble empirical mode decomposition with adaptive noise(CEEMDAN)is implemented based on the MATLAB platform,to decompose cardiopulmonary signals.A series of intrinsic mode functions(IMFs)are obtained from the decomposition.The traditional method of calculating heart rates by using fast Fourier transform(FFT)has been improved by the Hilbert transform,which can obtain the high-resolution marginal spectrums of the IMFs.Thus,the heart and respiratory rates can be calculated.The calculated heart and respiratory rates show high accuracy compared with the actual ones.This thesis focuses on a flexible PCB micro-coil and a portable electromagnetic induction cardiopulmonary signal detection system.The flexible PCB micro-coil can make the simultaneous collection of cardiopulmonary signals more accurate and improve comfortableness.Meanwhile,the heart and respiratory rates have been calculated correctly by using the CEEMDAN algorithm.The relative errors of heart and respiratory rates reach 1.37%and 3.35%,respectively on average.A feasible solution for the monitoring and separation of cardiopulmonary signals in mobile occasions has been proposed in this work,which is of great significance to the research field and clinical medicine.