Research On Mechanism Of Human Cardiac Electric Field Using Noncontact Detection

The human noncontact detection technology has important applications in anti-terrorism,anti-riot,local urban war,lifesaving efforts,and other fields.Human cardiac electric field noncontact detection is a new application of life science applicted in the target detection,which has the advantages of strong penetration,no radiation and well anti-interference.Aiming at the shorcomings of traditional human detection technology,this paper has finished the research on mechanism of human cardiac electric field using noncontact detection.Including the generation mechanism of human cardiac electric field,analysis the transmission characteristics of human cardiac electric field,analysis and comparison of cardiac electric field between human and several animals,and designing the testing system of simulating human cardiac electric field based on DSP 28335 processor.The main work of dissertation is as follows:1.Study on mechanism of human cardiac electric field.First of all,according to the heart electrophysiological theory,it was analyzed that the sodium-potassium pump in the myocardial cell membrane is to maintain the resting potential of myocardial cell.Taking sodium-potassium pump current balance potential as the field potential of the cardiac electric field,and the sodium-potassium pump current balance potential between human and several animals was deduced.Secondly,the human heart electric field was equivalent to an electric dipole.The electric field source potential of the entire heart was derived from the sodium-potassium pump current balance potential of a single myocardial cell,which was regarded as a target electric field potential for noncontact human detection.Finally,we get the difference of electric field characteristics between human and several animals based on the sodium-potassium pump current balance potential.2.Analysis the human cardiac electric field transmission characteristics.The equivalent impedance coupled circuit model of cardiac electric field transmission was obtained through the establishment of a cardiac-torso model.The transfer function of the cardiac electric field was deduced and the frequency response was analyzed.The results showed that the attenuation gain was-9.2d B ～ 9.0d B,phase advance 0 ～ 0.45 rad when the electric field radiated from the intro-body to the outer-body.Through the analysis of the equivalent coupling circuit simulation results,it is reasonable and feasible to establish the human cardiac electric field transmission model.3.The research on human and several animals cardiac electric field characteristics.The mathematical models of cardiac electric field in normal human beings,dying people,dogs,guinea pigs and rabbits were established,and the spectrum analysis were carried out.The results showed that the normal human heart electric field bandwidth ranged from 30 Hz ～47 Hz,the electric field bandwidth of the heart on the verge of death was 8 Hz,the heart electric field bandwidths of dogs,guinea pigs and rabbits ranged from 50 Hz ～ 90 Hz,120 Hz ～ 500 Hz,and 70 Hz ～ 120 Hz respectively.According to the results,the distinguishing standards of distinguishing humans and other animals based on the heart electric field were obtained in human noncontact detection.Thereby,it could realize the detection and recognition of the human target according to the distinguishing standards.4.Designed and developed the test system of simulating human cardiac electric field signal.Including the pre-signal conditioning amplifier circuit and DSP data collection system design,production,commissioning,signal processing algorithm simulation,simulation testing experiment of test system.Through the signal processing algorithm simulation experiments and simulation testing experiments verified that the hardware and software of test system were able to work properly to meet the requirements of technical indicators,strong stability,and well anti-interference,which provides the theoretical foundation and test system for following detection system of human cardiac electric field.