Modeling the frequency dependence of the electrical properties of the live human skull.

An accurate impedance model of a skull plays an important role in the simulation research on source localization of EEG and brain EIT (electrical impedance tomography), etc. On the basis of the large number of impedance and resistivity data obtained from our previous measurement on the live human skull, in this study we established the equivalent circuit models of six types of skull samples in the 30 Hz-3 MHz frequency range and analyzed the fitting performance of the models. The six types of skull samples are standard tri-layer, quasi-tri-layer, standard compact, quasi-compact, dentate suture and squamous suture. The results showed that the difference of the real part between the CPE (constant phase model) model and the measured data was less than 1% for all skull tissue types when the optimized characteristic parameters (rho(0), rho(infinity), alpha and f(c)) were adopted in the model. It is the first time studying the impedance model of different types of skulls, and it may provide accurate modeling of the skull to improve the accuracy of the related research on bioelectricity of the head and the biological effects of the electromagnetic field.