Effect of frozen-thaw injury on cell membrane and bio-impedance

Biological samples exhibit frequency dependent spectra caused by a dispersion mechanism. This dispersion mechanism demonstrates dielectric relaxation due to the interaction between electromagnetic field and biological samples at cellular levels. Hence, biological impedance spectroscopy may be used to reveal the electrical and geometrical properties of biological samples, in particular, frozen-thaw injury. Frozen-thaw injury is known as one of the most common factors that can influence the bio-impedance spectroscopy of biological samples. However, the mechanism of how frozen-thaw injury influences the bio-impedance spectroscopy at cellular levels has not been analysed. In this paper, the influence of frozen-thaw injury on beta dispersion was experimentally investigated using the AC conduction (contact electrode) method on potato and pork samples. From the results of the experiment, we assumed that frozen-thaw injury mainly influences the impedance spectroscopy of a potato and pork by breaking their cell membranes. In light of this assumption, a novel FEM model to simulate membrane breakage was developed and a microscopic experiment was then carried out to identify the membrane integrity. In this paper, the influence of frozen-thaw injury on dielectric properties of biological cells suspension was simulated using a custom developed FEM solver and an originally designed cell model. In its 2D version, the AC conduction case was simulated. Then, in the attempt to confirm the assumption, a microscopic experiment was conducted to determine if the cell membrane was broken or not. The measurement and simulation results suggest that bio-impedance measurements provide an indication of cellular structural changes of biological samples, which could be useful for biomedical, pharmaceutical and food inspection applications.