Experimental Verification of Dielectric Models with a Capacitive Wheatstone Bridge Biosensor for Living Cells: E. coli

Detection of bioparticles is of great importance in electrophoresis, identification of biomass sources, food and water safety, and other areas. It requires a proper model to describe bioparticles' electromagnetic characteristics. A numerical study of Escherichia coli bacteria during their functional activity was carried out by using two different geometrical models for the cells that considered the bacteria as layered ellipsoids and layered spheres. It was concluded that during cell duplication, the change in the dielectric permittivity of the cell is high enough to be measured at radio frequencies of the order of 50 kHz. An experimental setup based on the capacitive Wheatstone bridge was designed to measure relative changes in permittivity during cell division. In this way, the theoretical model was validated by measuring the dielectric permittivity changes in a cell culture of Escherichia coli ATTC 8739 from WDCM 00012 Vitroids. The spheroidal model was confirmed to be more accurate.

Automated summary

Detection and characterization of bioparticles is crucial in various fields, including electrophoresis, biomass identification, food and water safety. This study conducted a numerical investigation on Escherichia coli bacteria using two different geometrical models, layered ellipsoids and layered spheres. The results showed that the change in dielectric permittivity of the bacterial cells during cell duplication can be measured at radio frequencies of around 50 kHz. An experimental setup based on the capacitive Wheatstone bridge was designed and used to validate the theoretical model by measuring relative changes in permittivity during cell division. The study confirmed the accuracy of the spheroidal model.