An experimental study of electro-osmotic flow in rectangular microchannels

Sadr, Reza; Yoda, Minami; Zheng, Zhi; Conlisk, A. T.

doi:10.1017/s0022112004008626

Cited by 156 publications

(98 citation statements)

References 30 publications

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“…Values for varying from 0.15 to 0.5 have been suggested by various authors (see Hunter 1981;Scales et al 1992;Szymczyk et al 1999). We will assume here a value of 0.3 which is consistent with results of both Sadr et al (2004) and Yao et al (2003). The zeta-potential of the north and south channels are equal, ζ N = ζ S and the respective zeta-potentials in the west and east channels are a function of gamma…”

Section: Control Volume Analysismentioning

confidence: 71%

Convective instability of electrokinetic flows in a cross-shaped microchannel

Posner¹,

Santiago²

2006

J. Fluid Mech.

128

132

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We present a parametric experimental study of convective electrokinetic instability (EKI) in an isotropically etched, cross-shaped microchannel using quantitative epifluorescence imaging. The base state is a three-inlet, one-outlet electrokinetic focusing flow configuration where the centre sample stream and sheath flows have mismatched ionic conductivities. Electrokinetic flows with conductivity gradients become unstable when the electroviscous stretching and folding of conductivity interfaces grows faster than the dissipative effect of molecular diffusion. Scalar images, critical applied fields required for instability, and temporal and spatial scalar energy are presented for flows with a wide range of applied d.c. electric field and centre-tosheath conductivity ratios. These parameters impose variations of the electric Rayleigh number across four orders of magnitude. We introduce a scaling for charge density in the bulk fluid as a function of local maximum conductivity gradients in the flow. This scaling shows that the flow becomes unstable at a critical electric Rayleigh number (Ra e, = 205) and applies to a wide range of applied field and centre-tosheath conductivity ratios. This work is relevant to on-chip electrokinetic flows with conductivity gradients such as field amplified sample stacking, flow at the intersections of multi-dimensional assays, electrokinetic control and separation of sample streams with poorly specified chemistry, and low-Reynolds number micromixing.

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Section: Control Volume Analysismentioning

confidence: 71%

Convective instability of electrokinetic flows in a cross-shaped microchannel

Posner¹,

Santiago²

2006

J. Fluid Mech.

128

132

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“…A camera or a photodetector will record the movements of the fluorescent dye or particles and calculate the flow velocity values. For example, Sadr et al 46 studied EOF in rectangular channels by using nanoparticles; Jacobson et al 39,41 measured EOF velocity through nanochannels by using Rhodamine dye. EOF in single nanochannels was also investigated by Pennathur and Santiago by imaging Rhodamine B 35 .…”

Section: Eof Velocity Measurement By the Current Slope Methodsmentioning

confidence: 99%

Electroosmotic flow in single PDMS nanochannels

Peng

2016

Nanoscale

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Electroosmotic flow (EOF) velocity in single PDMS nanochannels with a dimension as small as 20 nm is investigated systematically by the current slope method in this paper. A novel method for fabrication of single nanochannels on PDMS surfaces is developed. The effects of channel size, ionic concentration of electrolyte solution and electric field on the EOF velocity in single nanochannels are investigated. The results show that EOF velocity in smaller nanochannels with overlapped electric double layers (EDL) is proportional to the applied electric field but is smaller than the EOF velocity in microchannels under the same applied electric field. EOF velocity in relatively large nanochannels without the overlap of EDLs is independent of the channels size and is the same as that in microchannels under the same applied electric field. Furthermore, in smaller nanochannels with overlapped EDLs, EOF velocity depends on the ionic concentration and also on the channel size. The experimental results reported in this paper are valuable for the future studies of electrokinetic nanofluidics.

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“…• In trying to build our intuition for reduced order modeling of the hydrodynamic interactions between Brownian particles, as needed for example for further study of colloidal ageing, we started to consider and then became further involved with a specific experiment with simpler Brownian effects, the nanoscale particle image velocimetry (nano-PIV or nPIV) measurements in Minami Yoda's group (Mechanical Engineering, Georgia Tech) [7,8], where the predominant interaction modeled is the hydrodynamics between a colloidal particle and the wall. Despite this simplicity, high-order numerical solution of the resulting system of stochastic differential equations by Milstein methods requires the proper construction of numerically evaluated Ito integrals, because the system is not "diagonal" in the stochastic sense (the particle diffusivity in each component depends on only one of the position components).…”

Section: Stochastic Reconstruction For Pivmentioning

confidence: 99%

Final Report: Model interacting particle systems for simulation and macroscopic description of particulate suspensions

Mucha¹

2007

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Review of Proposed Goals: Suspensions of solid particles in liquids appear in numerous applications, from environmental settings like river silt, to industrial systems of solids transport and water treatment, and biological flows such as blood flow. Despite their importance, much remains unexplained about these complicated systems. Mucha's research aims to improve understanding of basic properties of suspensions through a program of simulating model interacting particle systems with critical evaluation of proposed continuum equations, in close collaboration with experimentalists.Natural to this approach, the original proposal centered around collaboration with studies already conducted in various experimental groups. However, as was detailed in the 2004 progress report, following the first year of this award, a number of the questions from the original proposal were necessarily redirected towards other specific goals because of changes in the research programs of the proposed experimental collaborators. Nevertheless, the modified project goals and the results that followed from those goals maintain close alignment with the main themes of the original proposal, improving efficient simulation and macroscopic modeling of sedimenting and colloidal suspensions. In particular, the main investigations covered under this award have included 1. Sedimentation instabilities, including the sedimentation analogue of the Rayleigh-Taylor instability (for heavy, particle-laden fluid over lighter, clear fluid).2. Ageing dynamics of colloidal suspensions at concentrations above the glass transition, using simplified interactions.3. Stochastic reconstruction of velocity-field dependence for particle image velocimetry (PIV).4. Stochastic modeling of the near-wall bias in "nano-PIV".5. Distributed Lagrange multiplier simulation of the "internal splash" of a particle falling through a stable stratified interface.6. Fundamental study of velocity fluctuations in sedimentation.7. Parallelization of Mucha's "sort-and-sweep" sedimentation code.Details about publications and collaborators are provided topic-by-topic in the sections below.

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An experimental study of electro-osmotic flow in rectangular microchannels

Cited by 156 publications

References 30 publications

Convective instability of electrokinetic flows in a cross-shaped microchannel

Convective instability of electrokinetic flows in a cross-shaped microchannel

Electroosmotic flow in single PDMS nanochannels

Final Report: Model interacting particle systems for simulation and macroscopic description of particulate suspensions

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