Theory 43/Tissue/Bioimpedance
Tissue Conductivity Is a Volume Fraction
The claim
Tissue electrical conductivity is set by the ratio of extracellular volume fraction to membrane capacitance, so two tissues with the same water content can differ in impedance.
01Mechanism
Current flows through extracellular space at low frequency and through membranes at high; the ratio sets the frequency dependence.
02Prediction
Impedance should track the ratio.
03Refutation
Impedance tracking water content would remove membrane terms.