scholarly journals Continuous electroosmotic sorting of particles in grooved microchannels

Soft Matter ◽  
2017 ◽  
Vol 13 (41) ◽  
pp. 7498-7504 ◽  
Author(s):  
Alexander L. Dubov ◽  
Taras Y. Molotilin ◽  
Olga I. Vinogradova
Keyword(s):  
Electroosmotic Flow ◽  
Spherical Particles ◽  
Microfluidic Channels

A novel fractionation concept is proposed for spherical particles in grooved microfluidic channels with an electroosmotic flow.

Solute Dispersion by Electroosmotic flow in Nonuniform Microfluidic Channels

2001 ◽  
pp. 615-616 ◽  
Author(s):  
M. T. Blom ◽  
E. F. Hasselbrink ◽  
H. Wensink ◽  
A. van den Berg
Keyword(s):  
Electroosmotic Flow ◽  
Microfluidic Channels ◽  
Solute Dispersion

Light-induced thermoosmosis about conducting ellipsoidal nanoparticles

2019 ◽  
Vol 475 (2223) ◽  
pp. 20180040 ◽  
Author(s):  
Touvia Miloh
Keyword(s):  
Surface Temperature ◽  
Electroosmotic Flow ◽  
Spherical Particles ◽  
Conducting Liquid ◽  
Metallic Nanoparticle ◽  
Continuous Laser ◽  
Surface Slip ◽  
Physical Problems ◽  
Recent Advancement ◽  
Freely Suspended

We consider the central problem of a non-spherical (ellipsoidal) polarizable (metallic) nanoparticle freely suspended in a conducting liquid phase which is irradiated (heated) by a laser under the Rayleigh (electrostatic) approximation. It is shown that, unlike the case of perfectly symmetric (spherical) particles, the surface temperature of general orthotropic particles exposed to continuous laser irradiation is not uniform! Thus, the induced surface slip (Soret type) velocity may lead to a self-induced thermoosmotic flow (sTOF) about the particle, in a similar manner to the electroosmotic flow driven by the Helmholtz—Smoluchowski slippage. Using the recent advancement in the theory of Lamé functions and ellipsoidal harmonics, we analytically present new solutions for two key physical problems. (i) Heat conduction and temperature distribution inside and outside a conducting laser-irradiated homogeneous tri-axial ellipsoid which is subjected to uniform Joule heating. (ii) Creeping (Stokes) sTOF around a fixed impermeable metallic ellipsoidal nanoparticle driven by a Soret-type surface slip velocity (i.e. proportional to the surface-temperature gradient).

scholarly journals Force and torque on spherical particles in micro-channel flows using computational fluid dynamics

2016 ◽  
Vol 3 (7) ◽  
pp. 160298 ◽  
Author(s):  
Jin Suo ◽  
Erin E. Edwards ◽  
Ananyaveena Anilkumar ◽  
Todd Sulchek ◽  
Don P. Giddens ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cell Adhesion ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Spherical Particles ◽  
Microfluidic Channels ◽  
Cfd Modelling ◽  
Cfd Simulations ◽  
Hemodynamic Force

To delineate the influence of hemodynamic force on cell adhesion processes, model in vitro fluidic assays that mimic physiological conditions are commonly employed. Herein, we offer a framework for solution of the three-dimensional Navier–Stokes equations using computational fluid dynamics (CFD) to estimate the forces resulting from fluid flow near a plane acting on a sphere that is either stationary or in free flow, and we compare these results to a widely used theoretical model that assumes Stokes flow with a constant shear rate. We find that while the full three-dimensional solutions using a parabolic velocity profile in CFD simulations yield similar translational velocities to those predicted by the theoretical method, the CFD approach results in approximately 50% larger rotational velocities over the wall shear stress range of 0.1–5.0 dynes cm −2 . This leads to an approximately 25% difference in force and torque calculations between the two methods. When compared with experimental measurements of translational and rotational velocities of microspheres or cells perfused in microfluidic channels, the CFD simulations yield significantly less error. We propose that CFD modelling can provide better estimations of hemodynamic force levels acting on perfused microspheres and cells in flow fields through microfluidic devices used for cell adhesion dynamics analysis.

Lateral Migration of Neutrally-Buoyant Particles in a Square Microchannel at Low Reynolds Numbers

2009 ◽  
Author(s):  
Byung Rae Cho ◽  
Young Won Kim ◽  
Jung Yul Yoo
Keyword(s):  
Reynolds Numbers ◽  
Spherical Particles ◽  
Channel Cross Section ◽  
Microfluidic Channels ◽  
Lateral Migration ◽  
Low Reynolds Numbers ◽  
Low Reynolds ◽  
Square Microchannel ◽  
External Forces ◽  
Neutrally Buoyant

Lateral migration of particles has drawn a lot of attention in suspension community for the last 50 years. Since there is no need for extra external forces, lateral migration of particles plays an important role in constructing microfluidic devices in diverse engineering applications. In this paper, an experimental study on lateral migration of neutrally-buoyant spherical particles transported through a square microchannel is carried out using a fluorescent microscope at low Reynolds numbers. Fluorescent microspheres with diameters of d = 6 μm, 10 μm, and 16 μm are adopted as the test particles, which yield channel-to-particle size ratios of 13.3, 8 and 5, respectively. Spatial distributions of the particles in dilute suspension are visualized at different Reynolds numbers. It is shown that particles are uniformly distributed over the channel cross-section at relatively low Reynolds numbers. As the Reynolds number increases, however, particles migrate inward from the wall and away from the central axis of the channel, so that consequently they accumulate at an equilibrium position, exhibiting the so-called “tubular pinch effect”, first observed by Segre´ and Silberberg as early as in 1962. Experimental results obtained in this work offer design rules for microfluidic channels that play important roles of particle separation or particle focusing.

scholarly journals Joule heating and its effects on electroosmotic flow in microfluidic channels

2006 ◽  
Vol 34 ◽  
pp. 925-930 ◽  
Author(s):  
G Y Tang ◽  
D G Yan ◽  
C Yang ◽  
H Q Gong ◽  
C J Chai ◽  
...  
Keyword(s):  
Joule Heating ◽  
Electroosmotic Flow ◽  
Microfluidic Channels

Probing Electric Fields Inside Microfluidic Channels during Electroosmotic Flow with Fast-Scan Cyclic Voltammetry

2004 ◽  
Vol 76 (17) ◽  
pp. 4945-4950 ◽  
Author(s):  
Samuel P. Forry ◽  
Jacqueline R. Murray ◽  
Michael L. A. V. Heien ◽  
Laurie E. Locascio ◽  
R. Mark Wightman
Keyword(s):  
Cyclic Voltammetry ◽  
Electric Fields ◽  
Electroosmotic Flow ◽  
Microfluidic Channels ◽  
Fast Scan Cyclic Voltammetry

scholarly journals Electroosmotic flow of biorheological micropolar fluids through microfluidic channels

2018 ◽  
Vol 30 (2) ◽  
pp. 89-98 ◽  
Author(s):  
Mithilesh Kumar Chaube ◽  
Ashu Yadav ◽  
Dharmendra Tripathi ◽  
O. Anwar Bég
Keyword(s):  
Electroosmotic Flow ◽  
Microfluidic Channels ◽  
Micropolar Fluids

Geometry Effect on the Electrokinetic Instability of the Electroosmotic Flow in Microfluidic Channels

2008 ◽  
Author(s):  
Yee Cheong Lam ◽  
Gongyue Tang ◽  
Deguang Yan
Keyword(s):  
Threshold Voltage ◽  
Electroosmotic Flow ◽  
Fluorescent Imaging ◽  
Microfluidic Channels ◽  
Channel Geometry ◽  
Electrolyte Conductivity ◽  
Electrokinetic Instability ◽  
Micro Channels ◽  
Onset Voltage ◽  
Abrupt Contraction

To study the effect of geometry on electroosmotic flow in micro channels, we fabricated PDMS-glass microchannels of different designs, which have patterned channels with abrupt contraction of different sizes. Using fluorescent imaging technology, we demonstrated the effect of geometry on the instability of DC driven electroosmotic flow in microfluidic channels. For certain geometry and conductivity of the electrolyte solution (Sodium Bicarbonate), there is a threshold voltage for electroosmotic instability, exhibiting itself as “ripple”. Generally, the factors which affect the threshold voltage include channel width, channel geometry, and electrolyte conductivity. Narrower channel resulted in higher onset voltage. As conductivity of the electrolyte increases, the threshold voltage tends to increase. Early transition to unstable electroosmotic flow in microfluidic channels was observed under relatively low Re.

Electroosmotic Flow in “Click” Surface Modified Microfluidic Channels

2006 ◽  
Author(s):  
Shaurya Prakash ◽  
Timothy M. Long ◽  
Jonathan Wan ◽  
Jeffrey S. Moore ◽  
Mark A. Shannon
Keyword(s):  
Surface Charge ◽  
Photoelectron Spectroscopy ◽  
Electroosmotic Flow ◽  
Separation Efficiency ◽  
High Surface ◽  
High Surface Area ◽  
Attenuated Total Reflection ◽  
Covalent Attachment ◽  
Microfluidic Channels ◽  
Linear Polymers

A rapid, facile, and modular surface modification scheme for the covalent attachment of pre-formed polymer moieties to self-assembled monolayers via ‘click’ chemistry within glass microfluidic channels (3 cm long, 110 μm wide and 15 μm deep) is described. The effect that different moieties have on the electroosmotic flow (EOF) within the microchannels is evaluated. The application of linear polymers such as poly(ethylene glycol) (PEG) generates hydrophilic surfaces that reduce the analyte-wall interactions, thereby increasing separation efficiency and improving resolution, especially in bio-separations. Dendritic polymers such as poly(amido amine) (PAMAM) on channel walls can provide high-surface area structures with tunable surface charge depending on the generation of the dendrimer coating. Modified surfaces are characterized by X-ray photoelectron spectroscopy (XPS), Fourier Transform Infrared-Attenuated Total Reflection spectroscopy (FTIR-ATR), and contact angle measurements. EOF measurements in modified and unmodified channels provide information about wall-analyte interactions. A PAMAM dendrimer coated channel presents an amine terminated surface with a positive charge in contrast to a negatively charged bare-glass surface. Use of surface coatings can lead to an increase of the EOF by 15% as is the case for an azide terminated surface or reverse the direction of EOF as is the case for the PAMAM coatings by changing the surface charge polarity.

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