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The Py value, a fast measurable combination of the conductivity at the corner frequencies of the beta-dispersion, is a measure of the relative cell volume concentration in tissue. In many cases, if the biological object is stressed, for instance, by mechanical deformation, shortage of oxygen, electric field strength, temperature rise, or ischemia, Py increases. Depending on the object and the kind of stress, Py plateaus for minutes up to hours and then it decreases continuously. Values of passive electrical parameters of biological tissues are often given without information about the time following a stimulation or stress situation, for example, death, surgery, field application, etc. However, since the passive electrical properties change with time, information about their history, for example, time after death, should be given.

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Bio-impedance measurements are widely used for characterization of biological objects. Although the measured impedance of such objects is independent of the measurement method used, slight differences between measurements in the frequency and time domain are found. For many practical applications time domain based measurements are advantageous, but they are often rejected as not accurate. In order to show their suitability for bio-impedance measurements we used a special arrangement of time domain and frequency domain based measurements at the same biological specimen (canine liver) with the same electrodes. A reasonable coincidence in the measurement results could be shown. Moreover we used only a fraction of the time domain measurement data in order to demonstrate a significant reduction in measurement time while maintaining a reasonable accuracy. An algorithm for fast processing of the time domain data without transformation into the frequency domain is provided.