Non-linearity of the skin's AC impedance

The nonlinearity of the skin's AC impedance is a complex and fascinating problem. A custom-built, multichannel, in vivo impedance monitoring system was used to study and compare the skin's nonlinear behaviour under differing current amplitude conditions. Due to the complexity of the problem, care must be taken when planning such experiments. It was found that the source of the observed nonlinearity is the skin's parallel resistance. This resistance is nonlinear, even at low current densities of the order of 2 /spl mu/A/cm/sup 2/.