Magnetic Detection Electrical Impedance Tomography In The Meridian Research

The Meridian is an important component and the theory basis of Traditional Chinese Medicine. The research of essence and using modern scientific methods to reveal the existence forms and rules of the Meridian, is an important breakthrough to the integration of Traditional Chinese Medicine and modern science. Three-dimensional localization is the key to research of the Meridian Theory. Researchers have applied multi-disciplinary technical, for example, using electricity, sound, light, magnetic, thermal and isotopic methods to test the Meridian phenomenon, and as the attempt of the Meridian localization. The technology of using the electrical characteristics of meridians is mature. However, the research of electrical characteristics of the Meridian is basically concentrated in the skin surface, lacking the depth information and so on. So this paper proposes that applies the magnetic detection electrical impedance tomography to three-dimensional localization of the Meridian, which bases on the low resistance characteristics of the Meridians.Magnetic detection electrical impedance tomography utilizes magnetic induction principle to get impedance image, which included into electrical impedance tomography. Electrical impedance tomography includes applied current electrical impedance tomography, induced current electrical impedance tomography, magnetic resonance electrical impedance tomography, magnetic induction tomography, electro-magnetic impedance tomography electrical field tomography and magnetic detection electrical impedance tomography. Magnetic detection electrical impedance tomography has a lot of advantages, compared to other methods of electrical impedance tomography, for example, non-contact measurement, harmlessness, inexpensive, convenience and so on.This paper explores and designs the measurement system of magnetic detection electrical impedance tomography, including the excitation source, magnetic field sensor, mechanical scanning device, measurement circuit and data collection and transmission. The measurement circuit combines the systemic scaling method and analog orthogonal locked-in amplifier. The excitation signal is transformed into direct voltage, which provides the reference voltage of analog-to-digital converter and the denominator control voltage of multiplier. The errors caused by amplitude fluctuation are minimized. The experiments proof the measurement feasibility of magnetic detection electrical impedance tomography.The inverse problem of magnetic detection electrical impedance tomography includes the current density image reconstruction and conductivity image reconstruction. Current density image reconstruction is ill-posed, which does not meet the discrete Picard condition. The paper uses the regularization method, and proposes the non-negative non-negative regularization method for the current density construction. Simulation experiments are designed to verify and compare the various methods. The non-negative regularization 2, which uses generalized cross-validation method and Tikhonov regularization method, has the minimum relative error and can reconstructed better current density images. The software feasibility of magnetic detection electrical impedance tomography is proofed.