AC Insulator-Based Dielectrophoretic Focusing of Particles and Cells in an “Infinite” Microchannel

Malekanfard, Amirreza; Beladi-Behbahani, Shayesteh; Tzeng, Tzuen‐Rong; Zhao, Hui; Xuan, Xiangchun

doi:10.1021/acs.analchem.1c00697

Cited by 22 publications

(21 citation statements)

References 72 publications

(111 reference statements)

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“…where r p is the particle diameter and Re(f CM ) is the real part of the Clausius−Mossotti factor (f CM ), which accounts for the particle polarizability relative to that of the suspending medium. The f CM for both particles was assumed to be −0.5, 23 as the electrical conductivity of the microparticles is much lower than that of the medium; thus, all microparticles exhibited negative DEP behavior. A dependence with E 3 is assumed for EP (3) under the current operating conditions.…”

Section: ■ Theory and Computational Modelmentioning

confidence: 99%

High-Resolution Charge-Based Electrokinetic Separation of Almost Identical Microparticles

2022

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Well-established techniques, e.g., chromatography and capillary electrophoresis, are available for separating nanosized particles, such as proteins. However, similar techniques for separating micron-sized particles are still needed. Insulator-based electrokinetic (iEK) systems can achieve efficient microparticle separations by combining linear and nonlinear EK phenomena. Of particular interest are charge-based separations, which could be employed for separating similar microorganisms, such as bacterial cells of the same size, same genus, or same strain. Several groups have reported charge-based separations of microparticles where a zeta potential difference of at least 40 mV between the microparticles was required. The present work pushes the limit of the discriminatory capabilities of iEK systems by reporting the charged-based separation of two microparticles of the same size (5.1 μm), same shape, same substrate material, and with a small difference in particle zeta potentials of only 3.6 mV, which is less than 10% of the difference in previous studies. By building an accurate COMSOL Multiphysics model, which correctly accounts for dielectrophoresis and electrophoresis of the second kind, it was possible to identify the conditions to achieve this challenging separation. Furthermore, the COMSOL model allowed predicting particle retention times (t R,p) which were compared with experimental values (t R,e). The separations results had excellent reproducibility in terms of t R,e with variations of only 9% and 11% between repetitions. These findings demonstrate that, by following a robust protocol that involves modeling and experimental work, it is possible to discriminate between highly similar particles, with much smaller differences in electrical charge than previously reported.

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Section: ■ Theory and Computational Modelmentioning

confidence: 99%

High-Resolution Charge-Based Electrokinetic Separation of Almost Identical Microparticles

2022

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“…In another example of controlled iDEP for macroscopic particles, polystyrene beads and yeast cells were focused into a thin stream line using an applied field in the form of a 0.1 Hz square wave. In this situation the negative DEP force remained unchanged in direction but there was a periodic reversal of the electroosmotic and electrophoretic forces [96].…”

Section: Idepmentioning

confidence: 96%

Protein Dielectrophoresis: A Tale of Two Clausius-Mossottis—Or Something Else?

Pethig

2022

Micromachines

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Standard DEP theory, based on the Clausius–Mossotti (CM) factor derived from solving the boundary-value problem of macroscopic electrostatics, fails to describe the dielectrophoresis (DEP) data obtained for 22 different globular proteins over the past three decades. The calculated DEP force appears far too small to overcome the dispersive forces associated with Brownian motion. An empirical theory, employing the equivalent of a molecular version of the macroscopic CM-factor, predicts a protein’s DEP response from the magnitude of the dielectric β-dispersion produced by its relaxing permanent dipole moment. A new theory, supported by molecular dynamics simulations, replaces the macroscopic boundary-value problem with calculation of the cross-correlation between the protein and water dipoles of its hydration shell. The empirical and formal theory predicts a positive DEP response for protein molecules up to MHz frequencies, a result consistently reported by electrode-based (eDEP) experiments. However, insulator-based (iDEP) experiments have reported negative DEP responses. This could result from crystallization or aggregation of the proteins (for which standard DEP theory predicts negative DEP) or the dominating influences of electrothermal and other electrokinetic (some non-linear) forces now being considered in iDEP theory.

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“…( G.ii ) Illustration of the focusing of yeast cells under the influence of an AC potential of 100 V at a frequency of 0.1 Hz, the signal employed was a square wave. Adapted with permission from [120], copyright (2021) American Chemical Society.…”

Section: Insulator‐based Electrokinetic Analysis Of Intact Microorgan...mentioning

confidence: 99%

“…The Xuan research group has been a major contributor to the field of iEK systems, they have proposed innovative approaches for the manipulation of particles and cells [119]. In a 2021 report, they developed an "infinite" microchannel for microparticle and cell focusing, which was tested with yeast cells [120]. This device had triangular insulating structures on the channel walls (similar to the device from the Hayes group [99,100]), as shown in Figure 9G(i).…”

Section: Insulator-based Electrokinetic Analysis Of Cellsmentioning

confidence: 99%

Microscale electrokinetic‐based analysis of intact cells and viruses

Vaghef-Koodehi

Lapizco‐Encinas

2021

Electrophoresis

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Miniaturized electrokinetic methods have proven to be robust platforms for the analysis and assessment of intact microorganisms, offering short response times and higher integration than their bench‐scale counterparts. The present review article discusses three types of electrokinetic‐based methodologies: electromigration or motion‐based techniques, electrode‐based electrokinetics, and insulator‐based electrokinetics. The fundamentals of each type of methodology are discussed and relevant examples from recent reports are examined, to provide the reader with an overview of the state‐of‐the‐art on the latest advancements on the analysis of intact cells and viruses with microscale electrokinetic techniques. The concluding remarks discuss the potential applications and future directions.

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AC Insulator-Based Dielectrophoretic Focusing of Particles and Cells in an “Infinite” Microchannel

Cited by 22 publications

References 72 publications

High-Resolution Charge-Based Electrokinetic Separation of Almost Identical Microparticles

High-Resolution Charge-Based Electrokinetic Separation of Almost Identical Microparticles

Protein Dielectrophoresis: A Tale of Two Clausius-Mossottis—Or Something Else?

Microscale electrokinetic‐based analysis of intact cells and viruses

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