Kenneth S. Cole 1928a,b Papers

It was the Cole brothers who paved the way for an analytical, mathematical treatment of tissue immittivity and permittivity. K.S. Cole worked for a period in Debye s laboratory. 

In the theoretical part (1928a), he calculated the impedance of a suspension of spheres in which each sphere was coated with a layer having capacitive properties. He found expressions for the impedance at DC and infinite frequency (ro and roo, both purely resistive). 

He introduced a constant phase element (CPE), defined in the paper by the phase angle ( )3 = arccotan (m), and m = accordingly using m completely differently from Fricke ideal resistor has m = oo and )3 = 0°, and found the impedance locus for such a system was a circular arc with the center below the real axis in the Wessel diagram. A plot of complex immittance or immittivity in the Wessel diagram with the purpose of searching for circular arcs, may according to this book, be called a Cole-plot. 

He discussed the three-component electric equivalent circuit with two resistors (one ideal, lumped, physically realizable electronic component one frequency-dependent not realizable) and a capacitor (frequency-dependent) in two different configurations. He discussed his model first as a descriptive model, but later discussed Philippson s explanatory interpretation (extra-/intracellular liquids and cell membranes). 

In the experimental paper (1928b), he presented the measuring cell and tube oscillator used and the results obtained with a suspension of small eggs. The results were in accordance with the theory outlined in the previous paper (1928a). 

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