Creation of an electrokinetic characterization library for the detection and identification of biological cells

The rising concern over drug-resistant microorganisms has increased the need for rapid and portable detection systems. However, the traditional methods for the analysis of microorganisms can be both resource and time intensive. This contribution presents an alternative approach for the characterization of microorganisms using a microscale electrokinetic technique. The present study aims to develop and validate a library with a novel parameter referred to as the electrokinetic equilibrium condition for each strain, which will allow for fast identification of the studied bacterial and yeast cells in electrokinetic (EK) microfluidic devices. To create the library, experiments with six organisms of interest were conducted using insulator-based EK devices with circle-shaped posts. The organisms included one yeast strain, Saccharomyces cerevisiae; one salmonella strain, Salmonella enterica; two species from the same genus, Bacillus cereus and Bacillus subtilis; and two Escherichia coli strains. The results from these experiments were then analyzed with a mathematical model in COMSOL Multiphysics^®, which yielded the electrokinetic equilibrium condition for each distinct strain. Lastly, to validate the applicability EK library, the COMSOL model was used to estimate the trapping conditions needed in a device with oval-shaped posts for each organism, and these values were then compared with experimentally obtained values. The results suggest the library can be used to estimate trapping voltages with a maximum relative error of 12%. While the proposed electrokinetic technique is still a novel approach and the analysis of additional microorganisms would be needed to expand the library, this contribution further supports the potential of microscale electrokinetics as a technique for the rapid and robust characterization of microbes. Graphical abstract.