1R-2C model

Figure 10.4 shows dielectric models of the same tissue as shown in Figure 10.2. They have no DC conductance and basically have quite different spectra than the models of Figure 10.4. Fixed component values in the two dielectric models can be found so that they have exactly the same impedance spectrum. The same impedance spectrum with 2R-1C and 1R-2C models is not possible.

Figure 3.4 Dielectric (1R-2C) model circuit for a debye single dispersion. No DC conductance.

Figure 9.7 Dielectric 1R-2C models, (a) Parallel version and (b) series version.

A Cole—Cole plot is permittivity plotted in a Wessel diagram. If the permittivity is according to the Cole—Cole equation, the locus will be a circular arc. The permittivity used in the Cole—Cole equations implies that the model is changed from regarding tissue as a conductor (2R-1C model) to regarding tissue as a dielectric (1R-2C model) with only bound charges and dielectric losses. A 2R-1C model cannot have the same spectrum as a 1R-2C model with a fixed set of component values, so an arc locus in one model will not result in an arc locus in the other model. In living tissue, there is a substantial DC conductance. Such... 

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