Electrical Impedance Simulation and Characterization of Cell Growth Using the Fricke Model

For label-free and real-time monitoring of biological cells, electrical impedance sensing of the cells attached to the microelectrode has been used. In this article, the electrical impedance analysis of the cell growth using the Fricke model that consisted of the extracellular resistance parallel to the series combination of an intracellular resistance and the membrane-related capacitance was investigated. To relate the morphological changes in the cells that accompanied the cell growth in the Fricke model parameters, the impedance spectra of a cell model were simulated at different cell sizes and cell-cell gaps using the finite element method. The simulated results showed that the increase in the cell size results in an increment of the extracellular resistance and that the decrease in the cell-cell gap leads to an increment of the extracellular resistance and a decrement of the capacitance. Based on the theoretical relationship between the model parameters and the considered cellular behavior, it was shown that the measured impedance spectra of the cells were mostly governed by the change in the cell-cell gap at the beginning of the culture time, and then by the cell size or the density of the cells that covered the electrode surface with a limited area.