Abstract
A 4-layer concentric spherical model of human head was built to simulate the head EIT forward problem. The layers from outside to inside are scalp, skull, CFS (Cerebrospinal fluid) and brain tissue, respectively. A pair of point current sources placed on the outmost layer is regarded as the boundary condition, and an analytical method of separation of variables was employed to solve the problem. The electric potentials of different current injecting angles were calculated and the equipotential lines were drawn. The simulation results revealed that, the increment of the brain tissue conductivity causes decrease of the magnitude of both real and imaginary parts of the electric potential on the scalp. The frequency property of the model was simulated, when the exciting frequency was increased, the imaginary part of the electric potential increased significantly. These analytical solutions could be used to analyze the head EIT problems and check the numerical solutions calculated from FEM or BEM.