Basic Problems of the Electrical Measurement of Biological Tissues

许多研究人员从理论和实验上研究了生物组织的电学性质。但即使是现在，仍有许多问题没有得到解决。许多研究人员已经尝试将电阻抗方法应用于临床测量和治疗，如阻抗心动图、阻抗心动图、阻抗CT、体液容量测量、热疗、电磁波效应的估计等。然而，目前临床上应用较多、应用广泛、可靠的阻抗方法还很少。造成这个问题的原因有很多。最重要的问题是缺乏对生物组织的知识，因为生物组织的复杂性。在这项研究中，我们讨论了细胞悬浮液作为生物组织模型的电学性质。首先从理论上对其电学性质进行了讨论。针对血液结构简单的特点，对血液的电学特性进行了实验研究。这些理论和实验结果可广泛应用于电学方法在临床测量和治疗中的应用。阻抗法最有趣的应用之一是估计流体在体内的分布。尤其是细胞内外液体分布的估计对临床诊断具有重要意义。这种测量方法是基于β色散现象的。因此。生物组织电学特性的频率特性是研究生物组织电学特性的基础，本研究从理论上讨论了细胞悬浮液的电学特性，可以准确测量细胞内外流体的分布。

Electrical properties of living tissues have been studied both theoretically and experimentally by many researchers. But even now, there are many problems which remain unsolved.Many researchers have tried to apply the electrical impedance method to clinical measurement and therapy, such as impedance Plethysmography, impedance cardiography, impedance CT, fluid volume measurement, hyperthermia, estimation of the effects of electromagnetic wave and so on. However, we have only a few impedance method which is sufficient and is widely and reliably used in clinical field. There are many causes for this problem. The most important problems is the lack of knowledge about biological tissues, because of the complexity of biological tissues. In this research, we discussed the electrical properties of cell suspension as a model of biological tissues. At first the electrical properties are theoretically discussed. And then the electrical characteristics of blood are experimentally investigated because of the simplicity of blood structure. These theoretical and experimental results could be widely used for the application of electrical method to clinical measurement and therapy. One of the most interesting applications of impedance method is the estimation of fluid distribution in the body. Especially the estimation of intra- and extra-cellular fluid distribution is very important for clinical diagnosis. This measurement method is based on β dispersion phenomenon. Therefore. frequency characteristics of the electrical properties of biological tissues should be well investigated.In this research, we theoretically discussed the electrical properties of cell suspension, and we could accurately measure the intra- and extra-cellular fluid distribution.