I. Introduction
The measurement of electrical/electrochemical impedance is a powerful tool for investigating electric properties of biological cells suspended in a conductive medium [1], [2]. When these suspensions are exposed to an external electric field , at an arbitrary frequency , the cells are polarized, accumulating electrical charge at the interface of its shell and the surrounding medium. The polarization depends on the nature of the sample as well as on the frequency [3]. In general, the polarization does not reach instantaneously its steady-state, and it takes some time to reach its final value. Furthermore, when is suddenly removed, the polarization exponentially decays after a certain elapses [4]. This process is the so-called dielectric relaxation phenomenon, given by a relaxation time-constant . The electric response of cell suspensions is mainly supported on the effective medium theory and the Maxwell’s mixture model [5]. These models relate the intrinsic electrical properties of the suspension, the cell, the suspending medium and the volume fraction. Coupled with the physics-based models, in practice, one needs analytical techniques to assess the electrical response of the sample. Particularly, for biological cells, the electrical impedance spectroscopy (EIS) [6] is widely accepted as a label-free, non-invasive and quantitative analytical method that can thoroughly assess the electrical properties of biological cells [7].