Analysis of microorganisms with nonlinear electrokinetic microsystems

Abstract

Nonlinear electrokinetics (EK), specifically electrophoresis of the second kind, dielectrophoresis (DEP) and electrorotation (EROT), have gained significant interest recently for their flexibility and labeless discriminant manner of operation. The current applications of these technologies are a clear advancement from what they were when first discovered, but also still show strong signs of future growth. The present review article presents a discussion of the current uses of microscale nonlinear EK technologies as analytical, sensing, and purification tools for microorganisms. The discussion is focused on some of the latest discoveries with various nonlinear EK microfluidic techniques, such as DEP particle trapping and EROT for particle assessments, for the analysis of microorganisms ranging from viruses to parasites. Along the way, special focus was given to key research articles from within the past two years to provide the most up‐to‐date knowledge on the current state‐of‐the‐art within the field of microscale EK, and from there, an outlook on where the future of the field is headed is also included.

Microscale electrokinetic‐based analysis of intact cells and viruses

“…Polaczyk et al [4] recently published an excellent study on the calculation of zeta potential of microorganisms and Antunez-Vela et al [5], reported the first experimental assessment of the nonlinear electrophoretic mobility of bacterial and yeast cells. Exploiting differences in electrical properties offers an alternative for the rapid identification or separation of microorganisms [1,3].…”

“…Electromigration techniques also face challenges for the identification of highly similar microorganisms with comparable electromigration behavior. In these cases, nonlinear electrode-based or insulator-based EK systems can provide an alternative, as they have proved to have highly discriminatory capabilities for the analysis of a wide range of particles, from macromolecules to parasites [1,5,[13][14][15][16][17].…”

“…Traditional methods for the separation of intact microorganisms tend to have low selectivity, as many rely on size differentiation such as centrifugation, microfiltration, etc. Microscale electrokinetic (EK) methodologies offer inherent advantages for the analysis of small particles such as microorganisms [1]. Electric‐field‐driven or electromigration techniques, such as CE, offer a rapid and effective alternative for determining microbial contamination or infection [2].…”

“…[5], reported the first experimental assessment of the nonlinear electrophoretic mobility of bacterial and yeast cells. Exploiting differences in electrical properties offers an alternative for the rapid identification or separation of microorganisms [1,3].…”

Fluid rheological effects on streaming dielectrophoresis in a post‐array microchannel

“…Insulator-based dielectrophoresis (iDEP) is an emerging technique that has been increasingly used in the past two decades for microfluidic applications. It utilizes single or multiple insulating structures to create electric field gradients for various manipulations of particles and cells in Newtonian fluids [13][14][15][16]. However, many biological (e.g., blood and saliva) and chemical (e.g., colloidal and polymer solutions) fluids exhibit non-Newtonian characteristics [17,18].…”