The current density distribution of resistive disk surface electrodes

The current-density distribution of resistive disk surface electrodes is analyzed using a model in which the body is locally represented by a planar two-layer resistive medium and the electrode by a resistive disk with a concentric perfectly conducting feed contact. The exact current-density distribution on and in the electrode is obtained by solving a three-dimensional Laplace's equation numerically by means of the moment method. The following physical factors that affect the current-density distribution are analyzed: electrode size, feed region size, electrode thickness, electrode resistivity, skin conductivity, and skin thickness. The results demonstrate both an edge peak, which occurs with a highly conducting electrode on a uniform medium, and a peak in the current density near the feed region, which occurs if the electrode properties are not well matched to the properties of the tissues.>