Ultrafast electrokinetics

Youssefi, Mehrnaz Rouhi; Díez, F. J.

doi:10.1002/elps.201500392

Cited by 31 publications

(51 citation statements)

References 18 publications

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“…Very high electric fields (even just locally) are often necessary in these demonstrations . It is therefore fundamentally interesting and practically useful to understand if any other nonlinear effects may evolve under such harsh conditions such as the reported ultrafast electrophoresis and the modified Helmholtz–Smoluchowski slip velocity . There are a few other research directions in the field that the author considers worthy of future intensive studies and are each explained below: Current studies on electrokinetic transport and manipulation of particles in microchannels have been focused mainly upon Newtonian fluids despite the fact that many of the chemical and biological fluids in microfluidic applications possess non‐Newtonian characteristics .…”

Section: Discussionmentioning

confidence: 99%

“…Very high electric fields (even just locally) are often necessary in these demonstrations [31,90]. It is therefore fundamentally interesting and practically useful to understand if any other nonlinear effects may evolve under such harsh conditions such as the reported ultrafast electrophoresis [232] and the modified Helmholtz-Smoluchowski slip velocity [233]. There are a few other research directions in the field that the author considers worthy of future intensive studies and are each explained below:…”

Section: Discussionmentioning

confidence: 99%

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Recent advances in direct current electrokinetic manipulation of particles for microfluidic applications

Xuan

2019

Electrophoresis

101

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Microfluidic devices have been extensively used to achieve precise transport and placement of a variety of particles for numerous applications. A range of force fields have thus far been demonstrated to control the motion of particles in microchannels. Among them, electric field‐driven particle manipulation may be the most popular and versatile technique because of its general applicability and adaptability as well as the ease of operation and integration into lab‐on‐a‐chip systems. This article is aimed to review the recent advances in direct current (DC) (and as well DC‐biased alternating current) electrokinetic manipulation of particles for microfluidic applications. The electric voltages are applied through electrodes that are positioned into the distant channel‐end reservoirs for a concurrent transport of the suspending fluid and manipulation of the suspended particles. The focus of this review is upon the cross‐stream nonlinear electrokinetic motions of particles in the linear electroosmotic flow of fluids, which enable the diverse control of particle transport in microchannels via the wall‐induced electrical lift and/or the insulating structure‐induced dielectrophoretic force.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Recent advances in direct current electrokinetic manipulation of particles for microfluidic applications

Xuan

2019

Electrophoresis

101

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“…The two types of particles (PS 620 nm and PMMA 520 nm) were suspended in 1 mM KCl. Previously, two methods have been proposed to extract particle mobility in a high field: using asymmetric oscillating fields [27,31,32,41] and measuring bulk flow rate from the hydraulic height in a reservoir [30,42]. Here we used microfluidic channels and dc voltage to directly monitor particle motions, which allowed us to acquire nonlinear electrophoretic velocity on the single particle level precisely, without transient behavior, bubble generation, and pressure flow.…”

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confidence: 99%

Nonlinear Electrophoresis of Highly Charged Nonpolarizable Particles

et al. 2019

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Nonlinear field dependence of electrophoresis in high fields has been investigated theoretically, yet experimental studies have failed to reach consensus on the effect. In this work, we present a systematic study on the nonlinear electrophoresis of highly charged submicron particles in applied electric fields of up to several kV/cm. First, the particles are characterized in the low-field regime at different salt concentrations and the surface charge density is estimated. Subsequently, we use microfluidic channels and video tracking to systematically characterize the nonlinear response over a range of field strengths. Using velocity measurements on the single particle level, we prove that nonlinear effects are present at electric fields and surface charge densities that are accessible in practical conditions. Finally, we show that nonlinear behavior leads to unexpected particle trapping in channels. :1907.04278v1 [cond-mat.soft] arXiv

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“…Presented here are experimental and simulation data demonstrating the effects of EP (3) on electrokinetic injection and particle separation in insulator-based EK (iEK) systems. As recently demonstrated by several research groups [7,8,23,25,33,36,37], the electrophoresis of the second kind (EP (3) ) has a dominant effect on particle electromigration at high electric fields in iEK systems. Explicitly, the nonlinear phenomena of EP (3) must be considered when designing a separation process with an iEK system-those that include an EK injection in particular.…”

Section: Discussionmentioning

confidence: 93%

“…We attribute the high accuracy of the model to the inclusion of EP (3) . Only a handful of reports in the field of microscale EK separations have considered the effects of EP (3) in detail: five recent developments by our group [7,8,23,25,36] and the recent work of Rouhi et al [37] and Tottori et al [33]. Until recently, correction factors [38] were commonly added to mathematical models to improve the accuracy of modeling predictions.…”

Section: Methodsmentioning

confidence: 99%

Fine-Tuning Electrokinetic Injections Considering Nonlinear Electrokinetic Effects in Insulator-Based Devices

et al. 2021

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The manner of sample injection is critical in microscale electrokinetic (EK) separations, as the resolution of a separation greatly depends on sample quality and how the sample is introduced into the system. There is a significant wealth of knowledge on the development of EK injection methodologies that range from simple and straightforward approaches to sophisticated schemes. The present study focused on the development of optimized EK sample injection schemes for direct current insulator-based EK (DC-iEK) systems. These are microchannels that contain arrays of insulating structures; the presence of these structures creates a nonuniform electric field distribution when a potential is applied, resulting in enhanced nonlinear EK effects. Recently, it was reported that the nonlinear EK effect of electrophoresis of the second kind plays a major role in particle migration in DC-iEK systems. This study presents a methodology for designing EK sample injection schemes that consider the nonlinear EK effects exerted on the particles being injected. Mathematical modeling with COMSOL Multiphysics was employed to identify proper voltages to be used during the EK injection process. Then, a T-microchannel with insulating posts was employed to experimentally perform EK injection and separate a sample containing two types of similar polystyrene particles. The quality of the EK injections was assessed by comparing the resolution (Rs) and number of plates (N) of the experimental particle separations. The findings of this study establish the importance of considering nonlinear EK effects when planning for successful EK injection schemes.

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Ultrafast electrokinetics

Cited by 31 publications

References 18 publications

Recent advances in direct current electrokinetic manipulation of particles for microfluidic applications

Recent advances in direct current electrokinetic manipulation of particles for microfluidic applications

Nonlinear Electrophoresis of Highly Charged Nonpolarizable Particles

Fine-Tuning Electrokinetic Injections Considering Nonlinear Electrokinetic Effects in Insulator-Based Devices

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