Effect of Time Varying Magnetic Field on Sensory and Motor Nerve System

通过检测血液中涡流的强度和分布，探讨时变磁场对组织中电动势的影响。方法采用e型铁芯制作电磁铁，建立电磁回路，使交流电从电源流向电磁铁。研究了电磁回路的特性，测量了不同磁场作用下血液中的涡流。结果与讨论磁通量密度随通过电磁铁的电流升高而增大。在不同的磁场作用下，铜线圈内的电动势与通过电磁铁的电流的频率和强度以及铜线圈周围的面积成正比。结果表明，所观察到的电动势为感应电动势。如果暴露在磁场下的面积是固定的，则感应电流矩的大小与磁通量的密度成正比。血浆中诱导涡流最强，生理盐水次之，肝素化动脉血（全血）次之，充血红细胞次之。血浆、生理盐水、肝素化动脉血和填充红细胞中感应涡流的分布在腔室周围较低，在腔室中心较高。结果表明，即使介质成分不同，其分布方式也不会发生变化。探针处介质阻抗（1KHz, 1V）血浆为6.85K ω，肝素化动脉血为7.45 kω，填充红细胞为16.85 kω。血细胞等细胞成分增加越多，阻抗升高越高。这些结果表明，感应涡流的强度不仅与磁通量的密度有关，而且与介质中的阻抗有关。涡流有随介质阻抗增大而减小的趋势。少

The strength and distribution of eddy current in blood were examined for purpose of investigation of electromotive force in tissue induced by time varying magnetic field.Methods Electromagnet was made with E-typed iron core and electro magnetic circuit was established to circulate the alternating current from the source of electricity to electro magnet. The characteristic of electromagnetic circuit was examined and the eddy current in blood under exposure of varying magnetic field was measured.Results and Discussion The density of magnetic flux increased with elevation of electric current through the electro magnet. The electromotive force in copper wire coil induced by varying magnetic field was proportional to frequency and strength of electric current through the electro magnet and area surrounded by copper wire coil. These results showed that this electromotiveforce observed was induced electromotive force. If area under exposure of magnetic field is fixed, induced electromot ivefo … More rce is proportional to density of magnetic flux.Induced eddy current in blood was strongest in plasma and then was in order of normal saline, heparinized arterial blood (whole blood), packed red blood cell. The distribution of induced eddy current in plasma, normal saline, heparinized arterial blood and packed red blood cell was lower in the circumference of the chamber and higher in the center of the chamber. It was showed that the mode of distribution was not changed even if the component of medium was different. The impedance in the medium (measured at 1KHz, 1V) at the probe 6.85 K OMEGA in plaasm, 7.45KOMEGA in heparinized arterial blood, 16.85KOMEGA in packed red blood cell. The more cell component like blood cell increase, the higher the impedance elevate.These findings suggest that the strength of induced eddy current depends not only on the density of the magnetic flux but also on the impedance in the medium. The eddy current had tendency to reduce according to increase of impedance in medium. Less