Dielectrophoretic Microfluidic Device for Separating Microparticles Based on Size with Sub-Micron Resolution

Abstract

This article details the mathematical model of a microfluidic device aimed at separating any binary heterogeneous sample of microparticles into two homogeneous samples based on size with sub-micron resolution. The device consists of two sections, where the upstream section is dedicated to focusing of microparticles, while the downstream section is dedicated to separation of the focused stream of microparticles into two samples based on size. Each section has multiple planar electrodes of finite size protruding into the microchannel from the top and bottom of each sidewall; each top electrode aligns with a bottom electrode and they form a pair leading to multiple pairs of electrodes on each side. The focusing section subjects all microparticles to repulsive dielectrophoretic force, from each set of the electrodes, to focus them next to one of the sidewalls. This separation section pushes the big microparticles toward the interior, away from the wall, of the microchannel using repulsive dielectrophoretic force, while the small microparticles move unaffected to achieve the desired degree of separation. The operating frequency of the set of electrodes in the separation section is maintained equal to the cross-over frequency of the small microparticles. The working of the device is demonstrated by separating a heterogeneous mixture consisting of polystyrene microparticles of different size (radii of 2 and 2.25 μm) into two homogeneous samples. The mathematical model is used for parametric study, and the performance is quantified in terms of separation efficiency and separation purity; the parameters considered include applied electric voltages, electrode dimensions, outlet widths, number of electrodes, and volumetric flowrate. The separation efficiencies and separation purities for both microparticles are 100% for low volumetric flow rates, a large number of electrode pairs, large electrode dimensions, and high differences between voltages in both sections.

Dependence of Nonlinear Electrophoresis on Particle Size and Electrical Charge

“…Numerous separation processes of colloidal particles, including cells, exploit differences in the particle size. Our group has reported the EK size-based separation of polystyrene particles in a continuous mode and also, along with cells, in a trapping mode. , Other groups have also successfully demonstrated size-based separations of cells and polystyrene particles employing EK phenomena. − However, at high electric fields in systems stimulated with DC and low frequency AC potentials, nonlinear EP plays a major role in the overall migration of colloidal particles. Thus, it is essential to understand the influence of particle size on nonlinear electrophoretic effects, in particular, the effects of particle size on the mobility of the nonlinear electrophoretic velocity.…”

Electropatterning—Contemporary developments for selective particle arrangements employing electrokinetics

“…In this article, patterning approaches that use EFs will be referred to as “electropatterning.” The reports analyzed here include the deposition, orderly manipulation, and specific sorting of bioparticles. This review begins with simple colloidal arrangements and progresses to more complex macromolecular structures as EK properties may vary in size and structural complexity [33–36]. Although most of the compiled research studies have focused on manipulation by either electrophoresis (EP) or dielectrophoresis (DEP), some breakthroughs that combine these methods with other mechanical, optical, or magnetic forces are also included.…”

Advances in continuous-flow based microfluidic PCR devices—a review

“…Even after the above-mentioned traits of these microfluidic systems and tools for manipulation of fluid flow, each system is distinct, and accordingly, each microfluidic device has its own merits and demerits [26]. Usually, microfluidic deal with mixing, transferring, separating, and processing the fluids [27][28][29]. Further, as a passive technique, inertial microfluidic-based devices manipulate particles and cells by taking the advantage of hydrodynamic forces in microchips with a diversity of cross-sections [30].…”