An electrical impedance method using three phase eddy currents is proposed to measure the electric anisotropy of some organs like the liver consisting of anisotropic substances. In this method, three electromagnets are used and placed in an equilateral triangle on the surface of the substance. Three phase alternative currents are applied to each coil of those three electromagnets, respectively, so that three phase eddy currents are produced at the center of the triangle in the substance. The superposed current of these three phase eddy currents is used to measure the impedance. Because the flow direction of this superposed current rotates through 360 degrees around the center of three magnets during one cycle of the alternative current, the anisotropic impedance can be measured. The detection of anisotropic impedance by the proposed method was confirmed with some model experiments and in-vivo measurements of the liver of pigs.
