scholarly journals Electroosmotic Flow of Viscoelastic Fluid through a Constriction Microchannel

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 417
Author(s):  
Jianyu Ji ◽  
Shizhi Qian ◽  
Zhaohui Liu
Keyword(s):  
Electric Field ◽  
Newtonian Fluid ◽  
Viscoelastic Fluid ◽  
Apparent Viscosity ◽  
Applied Electric Field ◽  
Electroosmotic Flow ◽  
Microfluidic Channel ◽  
Critical Value ◽  
Poisson Boltzmann ◽  
Boltzmann Model

Electroosmotic flow (EOF) has been widely used in various biochemical microfluidic applications, many of which use viscoelastic non-Newtonian fluid. This study numerically investigates the EOF of viscoelastic fluid through a 10:1 constriction microfluidic channel connecting two reservoirs on either side. The flow is modelled by the Oldroyd-B (OB) model coupled with the Poisson–Boltzmann model. EOF of polyacrylamide (PAA) solution is studied as a function of the PAA concentration and the applied electric field. In contrast to steady EOF of Newtonian fluid, the EOF of PAA solution becomes unstable when the applied electric field (PAA concentration) exceeds a critical value for a fixed PAA concentration (electric field), and vortices form at the upstream of the constriction. EOF velocity of viscoelastic fluid becomes spatially and temporally dependent, and the velocity at the exit of the constriction microchannel is much higher than that at its entrance, which is in qualitative agreement with experimental observation from the literature. Under the same apparent viscosity, the time-averaged velocity of the viscoelastic fluid is lower than that of the Newtonian fluid.

Synergistic use of electroosmotic flow and magnetic forces for nucleic acid extraction

The Analyst ◽  
2020 ◽  
Vol 145 (6) ◽  
pp. 2412-2419 ◽  
Author(s):  
Rachel N. Deraney ◽  
Lindsay Schneider ◽  
Anubhav Tripathi
Keyword(s):  
Nucleic Acid ◽  
Electric Field ◽  
Microfluidic Chip ◽  
Applied Electric Field ◽  
Electroosmotic Flow ◽  
Acid Extraction ◽  
Nucleic Acid Extraction ◽  
Magnetic Forces ◽  
Extraction And Purification

NA extraction and purification utilitzing a microfluidic chip with applied electric field to induce electroosmotic flow opposite the magnetic NA-bound bead mix.

ELECTRIC-FIELD-INDUCED LAMELLAR STRUCTURES IN MAGNETIC FLUIDS — A 2D DIFFUSION MODEL

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2341-2344 ◽  
Author(s):  
BRETT RILEY ◽  
ANIKET BHATTACHARYA ◽  
MICHAEL JOHNSON ◽  
XIAODONG DUAN ◽  
WEILI LUO
Keyword(s):  
Phase Separation ◽  
Electric Field ◽  
Diffusion Model ◽  
Magnetic Fluid ◽  
Applied Electric Field ◽  
Continuity Equation ◽  
Fluid Layer ◽  
Critical Value ◽  
Lamellar Structures ◽  
2D Simulation

A lamellar pattern can form in a thin magnetic fluid layer when the applied electric field is above a critical value. A 2D simulation is performed to study the field-induced phase separation and the pattern by using the mass continuity equation. The simulation produces the similar structure in field but does not match the experimental growth law.

Two-Fluid Electroosmotic Flow in Microchannels

2008 ◽  
Author(s):  
T. N. Wong ◽  
Y. Gao ◽  
C. Wang ◽  
C. Yang ◽  
N. T. Nguyen ◽  
...  
Keyword(s):  
Electric Field ◽  
Applied Electric Field ◽  
Electroosmotic Flow ◽  
Viscosity Ratio ◽  
Experimental Investigations ◽  
Fluid Interface ◽  
Surface Charges ◽  
Interface Position ◽  
Proposed Model ◽  
Two Fluid

This paper presents theoretical and experimental investigations of the pressure-driven two-liquid flow in microchannels with the electroosmosis effect. For a fully developed, steady state, laminar flow of two liquids combined the pressure gradient, electroosmosis and surface charges at the liquid-liquid interface, we have derived analytical solutions that relate the velocity profiles and flow rates to the liquid holdup, the aspect ratio of the microchannel, the viscosity ratio of the two liquids and the externally applied electric field. It was shown that adjusting the externally applied electric field could control the fluid interface position precisely. The prediction from the proposed model compares very well with measured data.

Symmetry Breaking in ER and MR Fluids Under Shear

2000 ◽  
Author(s):  
R. Tao ◽  
J. Zhang ◽  
Y. Shiroyanagi ◽  
X. Tang ◽  
X. Zhang
Keyword(s):  
Symmetry Breaking ◽  
Electric Field ◽  
Shear Strain ◽  
Applied Electric Field ◽  
Shear Force ◽  
Critical Value ◽  
Mr Fluids

Abstract The behavior of an electtorheological (ER) chain under a shear force is investigated theoretically and experimentally. Contrary to the conventional assumption that the ER chain under a shear force becomes slanted and breaks at the middle, we have found that there is symmetry breaking. When the shear strain is small, the chain becomes slanted with a space gap between the first and second particles (or between the last and next last particles). As the shear strain increases, the gap becomes wider and wider. When the shear strain exceeds a critical value, the chain breaks at the gap. The experiment also confirms that an ER chain under the shear breaks at either end, not at the middle. This symmetry breaking reflects the space’s anisotropy, which is the result of the applied electric field.

ELECTRORHEOLOGICAL FLUIDS UNDER SHEAR

2001 ◽  
Vol 15 (06n07) ◽  
pp. 918-929 ◽  
Author(s):  
R. Tao ◽  
J. Zhang ◽  
Y. Shiroyanagi ◽  
X. Tang ◽  
X. Zhang
Keyword(s):  
Symmetry Breaking ◽  
Electric Field ◽  
Shear Strain ◽  
Applied Electric Field ◽  
Shear Force ◽  
Critical Value ◽  
Electrorheological Fluids

The behavior of an electrorheological (ER) chain under a shear force is investigated theoretically and experimentally. Contrary to the conventional assumption that the ER chain under a shear force becomes slanted and breaks at the middle, we have found that there is symmetry breaking. When the shear strain is small, the chain becomes slanted with a space gap between the first and second particles (or between the last and next last particles). As the shear strain increases, the gap becomes wider and wider. When the shear strain exceeds a critical value, the chain breaks at the gap. The experiment also confirms that an ER chain under the shear breaks at either end, not at the middle. This symmetry breaking reflects the space's anisotropy, which is the result of the applied electric field.

scholarly journals Numerical Investigation of Nanostructure Orientation on Electroosmotic Flow

Micromachines ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 971
Author(s):  
An Eng Lim ◽  
Yee Cheong Lam
Keyword(s):  
Electric Field ◽  
Field Distribution ◽  
Applied Electric Field ◽  
Electroosmotic Flow ◽  
Electric Field Distribution ◽  
Flow Direction ◽  
Fluid Velocity ◽  
Orientation Angle ◽  
Dependent Behavior ◽  
Velocity Region

Electroosmotic flow (EOF) is fluid flow induced by an applied electric field, which has been widely employed in various micro-/nanofluidic applications. Past investigations have revealed that the presence of nanostructures in microchannel reduces EOF. Hitherto, the angle-dependent behavior of nanoline structures on EOF has not yet been studied in detail and its understanding is lacking. Numerical analyses of the effect of nanoline orientation angle θ on EOF to reveal the associated mechanisms were conducted in this investigation. When θ increases from 5° to 90° (from parallel to perpendicular to the flow direction), the average EOF velocity decreases exponentially due to the increase in distortion of the applied electric field distribution at the structured surface, as a result of the increased apparent nanolines per unit microchannel length. With increasing nanoline width W, the decrease of average EOF velocity is fairly linear, attributed to the simultaneous narrowing of nanoline ridge (high local fluid velocity region). While increasing nanoline depth D results in a monotonic decrease of the average EOF velocity. This reduction stabilizes for aspect ratio D/W > 0.5 as the electric field distribution distortion within the nanoline trench remains nearly constant. This investigation reveals that the effects on EOF of nanolines, and by extrapolation for any nanostructures, may be directly attributed to their effects on the distortion of the applied electric field distribution within a microchannel.

Influence of the Electrophoretic Motion of Particle Suspensions on the Bulk Electroosmotic Flow of Water Through Fused Silica Capillaries

2005 ◽  
Author(s):  
J. Young ◽  
D. Maynes ◽  
B. W. Webb
Keyword(s):  
Chemical Composition ◽  
Electric Field ◽  
Applied Electric Field ◽  
Electroosmotic Flow ◽  
Charged Particles ◽  
Fused Silica ◽  
Particle Type ◽  
Fused Silica Capillaries ◽  
Silica Capillaries ◽  
Positively Charged

The influence of microparticles on electroosmotic flow was investigated experimentally. Experiments were conducted using four different particle types of varying chemical composition, surface charge and polarity. Each particle type was tested at five different volume fractions ranging from 0.001 – 0.025. With a constant applied electric field, positively charged particles enhanced the electroosmotic flow by as much as 800%. The enhancement depended on particle composition, size and concentration. For negatively charged particles, the bulk electroosmotic flow was retarded with the largest reductions being 35%.

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