A Study on Broadband Electrical Properties of E. Coli Bacteria Suspension for Varied Concentration

In this paper, an experimental study is conducted to assess the electrical properties of E. Coli bacteria suspended in phosphate-buffered saline. A direct broadband dielectric spectroscopy utilizing a two-wire sensor is applied to derive permittivity data which depends on the bacteria concentration. In such approach, the bacteria suspension constitutes full the propagation medium while the dielectric properties are averaged within a larger (sub-ml) volume of liquid which is favourable for heterogenous mixtures. A set of bacteria samples of known concentrations was prepared for the experiment along with a dedicated sensor optimized for measuring liquids of high permittivity and loss being developed. A measurement setup was assembled, and measurements were carried out with controlled and stable environment conditions. The obtained results are crucial for the development of novel highly sensitive and cost-effective microwave biosensors.