Spatial Resolution of Four Electrode Array

The in vivo measurement of specific impedance in brain tissue involves several technical aspects. The most stringent difficulties relate to electrode polarization and spatial resolution of the measuring system. The polarization is solved by usinga four electrode arrangement with a very high impedance preamplifier on the potential electrodes. This paper discusses the relative effectiveness of the various possible linear configurations of four electrodes in terms of spatial resolution. The accuracy of computed spatial resolution with respect to corresponding experimental ones is specified.