Control of two-phase flow in microfluidics using out-of-phase electroconvective streaming

Liu, Weiyu; Ren, Yukun; Tao, Ye; Chen, Xiaoming; Yao, Baoquan; Hui, Meng; Bai, Lin

doi:10.1063/1.5003973

Cited by 46 publications

(35 citation statements)

References 37 publications

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“…The aqueous solution is preferentially selected here as the suspension medium, so that the flow field is governed by the standard Navier–Stokes equation for a Newtonian fluid :

ρ \frac{\partial u}{\partial t} + ρ (u \cdot \nabla) u = \nabla \cdot [- p I + η (\nabla u + {((), \nabla u)}^{normalT})] + F,

\nabla \cdot u = 0,

where ρ = 1000 kg/m 3 is the liquid mass density, p is the static pressure, I is the unit tensor, η is the liquid dynamic viscosity, and F is a source term representing any external force exerted on the liquid bulk. In the present analysis, we take into consideration the possible existence of an extended space charge layer undergoing Coulomb force :

F = ρ_{f} E = F (c_{1} - c_{2}) E

…”

Section: Methodsmentioning

confidence: 99%

On ion transport regulation with field‐effect nonlinear electroosmosis control in microfluidics embedding an ion‐selective medium

et al. 2020

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On ion transport regulation with field-effect nonlinear electroosmosis control in microfluidics embedding an ion-selective mediumWe study herein numerically the use of induced-charge electrokinetic phenomena to enable a flexible control of ion transport of dilute electrolyte in a straight ion concentration polarization system. The effect of three convection modes of induced-charge electrokinetic phenomena, including induced-charge electroosmosis, flow-field effect transistor, and alternating-current electroosmosis (ACEO), on convective arrestment of diffusive wave-front propagation is investigated by developing a cross-scale and fully coupled transient numerical simulation model, wherein multiple frequency electrochemical polarization and nonlinear diffuse charge dynamics in spatiotemporally varying solution conductivity are taken into account. We demonstrate by detailed comparative simulation studies that ACEO vortex flow field above a metal strip array arranged along the anodic chamber's bottom surface serves as the most efficient way for adjusting the salt density distribution at micrometer and even millimeter dimension, due to its high flexibility in controlling the stirring flow state with the introduction of two extra electrical parameters. The specific operating status is determined by whether the electrode array is floating in potential (induced-charge electroosmosis) or biased to ground (flow-field effect transistor) or forced to oscillate at another Fourier mode (ACEO). These results prove useful for on-chip electric current control with electroconvective stirring.

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“…The aqueous solution is preferentially selected here as the suspension medium, so that the flow field is governed by the standard Navier–Stokes equation for a Newtonian fluid :

ρ \frac{\partial u}{\partial t} + ρ (u \cdot \nabla) u = \nabla \cdot [- p I + η (\nabla u + {((), \nabla u)}^{normalT})] + F,

\nabla \cdot u = 0,

F = ρ_{f} E = F (c_{1} - c_{2}) E

…”

Section: Methodsmentioning

confidence: 99%

On ion transport regulation with field‐effect nonlinear electroosmosis control in microfluidics embedding an ion‐selective medium

et al. 2020

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“…It is presumed that the applied AC voltage has a single Fourier component oscillating at the base frequency, i.e.,

, where

capped with a tilde symbol signifies the complex phasor amplitude of electrostatic potential

[ 65 ]. The tilde symbol ~ is dropped henceforward for convenience of expression.…”

Section: Methodsmentioning

confidence: 99%

On AC-Field-Induced Nonlinear Electroosmosis next to the Sharp Corner-Field-Singularity of Leaky Dielectric Blocks and Its Application in on-Chip Micro-Mixing

et al. 2018

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Induced-charge electroosmosis has attracted lots of attention from the microfluidic community over the past decade. Most previous researches on this subject focused on induced-charge electroosmosis (ICEO) vortex streaming actuated on ideally polarizable surfaces immersed in electrolyte solutions. Starting from this point, we conduct herein a linear asymptotic analysis on nonlinear electroosmotic flow next to leaky dielectric blocks of arbitrary electrical conductivity and dielectric permittivity in harmonic AC electric fields, and theoretically demonstrate that observable ICEO fluid motion can be generated at high field frequencies in the vicinity of nearly insulating semiconductors, a very low electrical conductivity, of which can evidently increase the double-layer relaxation frequency (inversely proportional to the solid permittivity) to be much higher than the typical reciprocal RC time constant for induced double-layer charging on ideally polarizable surfaces. A computational model is developed to study the feasibility of this high-frequency vortex flow field of ICEO for sample mixing in microfluidics, in which the usage of AC voltage signal at high field frequencies may be beneficial to suppress electrochemical reactions to some extent. The influence of various parameters for developing an efficient mixer is investigated, and an integrated arrangement of semiconductor block array is suggested for achieving a reliable mixing performance at relatively high sample fluxes. Our physical demonstration with high-frequency ICEO next to leaky dielectric blocks using a simple channel structure offers valuable insights into the design of high-throughput micromixers for a variety of lab-on-a-chip applications.

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“…Under the Debye–Huckel limit, the electrostatic potential field in the bulk fluid and dielectric membrane are both governed by the Laplace equation with zero volumetric free charge density [ 55 , 56 , 57 , 58 , 59 ]:

…”

Section: Methodsmentioning

confidence: 99%

On the Bipolar DC Flow Field-Effect-Transistor for Multifunctional Sample Handing in Microfluidics: A Theoretical Analysis under the Debye–Huckel Limit

Liu

Ren

et al. 2018

Micromachines

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We present herein a novel method of bipolar field-effect control on DC electroosmosis (DCEO) from a physical point of view, in the context of an intelligent and robust operation tool for stratified laminar streams in microscale systems. In this unique design of the DC flow field-effect-transistor (DC-FFET), a pair of face-to-face external gate terminals are imposed with opposite gate-voltage polarities. Diffuse-charge dynamics induces heteropolar Debye screening charge within the diffuse double layer adjacent to the face-to-face oppositely-polarized gates, respectively. A background electric field is applied across the source-drain terminal and forces the face-to-face counterionic charge of reversed polarities into induced-charge electroosmotic (ICEO) vortex flow in the lateral direction. The chaotic turbulence of the transverse ICEO whirlpool interacts actively with the conventional plug flow of DCEO, giving rise to twisted streamlines for simultaneous DCEO pumping and ICEO mixing of fluid samples along the channel length direction. A mathematical model in thin-layer approximation and the low-voltage limit is subsequently established to test the feasibility of the bipolar DC-FFET configuration in electrokinetic manipulation of fluids at the micrometer dimension. According to our simulation analysis, an integrated device design with two sets of side-by-side, but upside-down gate electrode pair exhibits outstanding performance in electroconvective pumping and mixing even without any externally-applied pressure difference. Moreover, a paradigm of a microdevice for fully electrokinetics-driven analyte treatment is established with an array of reversed bipolar gate-terminal pairs arranged on top of the dielectric membrane along the channel length direction, from which we can obtain almost a perfect liquid mixture by using a smaller magnitude of gate voltages for causing less detrimental effects at a small Dukhin number. Sustained by theoretical analysis, our physical demonstration on bipolar field-effect flow control for the microfluidic device of dual functionalities in simultaneous electroconvective pumping and mixing holds great potential in the development of fully-automated liquid-phase actuators in modern microfluidic systems.

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Control of two-phase flow in microfluidics using out-of-phase electroconvective streaming

Cited by 46 publications

References 37 publications

On ion transport regulation with field‐effect nonlinear electroosmosis control in microfluidics embedding an ion‐selective medium

On ion transport regulation with field‐effect nonlinear electroosmosis control in microfluidics embedding an ion‐selective medium

On AC-Field-Induced Nonlinear Electroosmosis next to the Sharp Corner-Field-Singularity of Leaky Dielectric Blocks and Its Application in on-Chip Micro-Mixing

On the Bipolar DC Flow Field-Effect-Transistor for Multifunctional Sample Handing in Microfluidics: A Theoretical Analysis under the Debye–Huckel Limit

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