Hydrodynamic Dispersion of a Neutral Nonreacting Solute in Electroosmotic Flow

Griffiths, Stewart K.; Nilson, Robert H.

doi:10.1021/ac990714w

Cited by 93 publications

(108 citation statements)

References 4 publications

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“…Velocity gradients across the channel cross section are central to dispersion, as they induce a shearing action ͑Taylor, 1953͒. Convective dispersion in microfluidic channels has been reviewed by Squires and Quake ͑2005͒; it is different for pressuredriven and electro-osmotic flow due to their parabolic and plug flow profiles, respectively ͑Griffiths and Nilson, 1999Stein et al, 2006͒. In nanochannels, the previously mentioned electrokinetic effects increase the dispersion rate of counterions and decrease the rate of coions ͑De Leebeeck and Sinton, 2006͒. These authors also showed that the radially limited diffusion of ions by electromigration in response to the wall charge increases the dispersion of all ions relative to neutral species.…”

Section: ͑29͒mentioning

confidence: 99%

Transport phenomena in nanofluidics

2008

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The transport of fluid in and around nanometer-sized objects with at least one characteristic dimension below 100 nm enables the occurrence of phenomena that are impossible at bigger length scales. This research field was only recently termed nanofluidics, but it has deep roots in science and technology. Nanofluidics has experienced considerable growth in recent years, as is confirmed by significant scientific and practical achievements. This review focuses on the physical properties and operational mechanisms of the most common structures, such as nanometer-sized openings and nanowires in solution on a chip. Since the surface-to-volume ratio increases with miniaturization, this ratio is high in nanochannels, resulting in surface-charge-governed transport, which allows ion separation and is described by a comprehensive electrokinetic theory. The charge selectivity is most pronounced if the Debye screening length is comparable to the smallest dimension of the nanochannel cross section, leading to a predominantly counterion containing nanometer-sized aperture. These unique properties contribute to the charge-based partitioning of biomolecules at the microchannel-nanochannel interface. Additionally, at this free-energy barrier, size-based partitioning can be achieved when biomolecules and nanoconstrictions have similar dimensions. Furthermore, nanopores and nanowires are rooted in interesting physical concepts, and since these structures demonstrate sensitive, label-free, and real-time electrical detection of biomolecules, the technologies hold great promise for the life sciences. The purpose of this review is to describe physical mechanisms on the nanometer scale where new phenomena occur, in order to exploit these unique properties and realize integrated sample preparation and analysis systems.

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Section: ͑29͒mentioning

confidence: 99%

Transport phenomena in nanofluidics

2008

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“…However, it provides no direct knowledge of either the mean migration velocity or the effective dispersion coefficient of solutes, where the former determines whether solutes can be separated while the latter governs the resolution [21]. As the hydrodynamic dispersion is proportional to the square of the channel transverse dimension in both pressure- [22,23] and electric field-driven flows [24,25], it becomes trivial in nanochannels even though the variation of fluid velocity across the channel may become very significant [6][7][8][9][11][12][13][14][15]. Moreover, such dispersion has no direct influence on the mean migration velocity of solutes.…”

Section: Solute Transport In Nanofluidic Channelsmentioning

confidence: 99%

Solute separation in nanofluidic channels: Pressure‐driven or electric field‐driven?

Xuan

2007

Electrophoresis

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We demonstrate theoretically that solute separation can be accomplished in pressure-driven flow through nanochannels due to solute-wall interactions. Such pressure-driven separation is efficient in identifying solutes with variable valences. This function complements exactly the electric field-driven separation (i.e., electrophoretic separation) in nanofluidic channels that works well for solutes differing in diffusivity. We also demonstrate the enhanced separation of solutes of either different valence or different diffusivity through the combination of a pressure-driven flow and an electric field-driven backflow in nanofluidic channels. This combined flow, however, has to be used with caution for solutes varying in both valence and diffusivity.

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“…Some of them addressed pressure-driven flow, whereas in some studies electrically driven flow and combined pressure-electrically-driven flow were considered. Assuming low electric potentials at the wall/solution interface, Datta (1990), McEldoon and Datta (1992), and Griffiths and Nilson (1999) evaluated the electroosmotic dispersion coefficient for the circular and plane parallel channels. For higher wall potentials, the electroosmotic dispersion was addressed by Lisin (1992, 1993), Gas et al (1995), Griffiths and Nilson (2000), and Zholkovskij et al (2003).…”

Section: Introductionmentioning

confidence: 99%

Dispersion in electroosmotic flow generated by oscillatory electric field interacting with oscillatory wall potentials

Paul

2011

Microfluid Nanofluid

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An analytical study is presented in this article on the dispersion of a neutral solute released in an oscillatory electroosmotic flow (EOF) through a two-dimensional microchannel. The flow is driven by the nonlinear interaction between oscillatory axial electric field and oscillatory wall potentials. These fields have the same oscillation frequency, but with disparate phases. An asymptotic method of averaging is employed to derive the analytical expressions for the steady-flow-induced and oscillatory-flow-induced components of the dispersion coefficient. Dispersion coefficients are functions of various parameters representing the effects of electric double-layer thickness (Debye length), oscillation parameter, and phases of the oscillating fields. The time-harmonic interaction between the wall potentials and electric field generates steady as well as time-oscillatory components of electroosmotic flow, each of which will contribute to a steady component of the dispersion coefficient. It is found that, for a thin electric double layer, the phases of the oscillating wall potentials will play an important role in determining the magnitude of the dispersion coefficient. When both phases are zero (i.e., full synchronization of the wall potentials with the electric field), the flow is nearly a plug flow leading to very small dispersion. When one phase is zero and the other phase is p, the flow will be sheared to the largest possible extent at the center of the channel, and such a sharp velocity gradient will lead to the maximum possible dispersion coefficient.

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Hydrodynamic Dispersion of a Neutral Nonreacting Solute in Electroosmotic Flow

Cited by 93 publications

References 4 publications

Transport phenomena in nanofluidics

Transport phenomena in nanofluidics

Solute separation in nanofluidic channels: Pressure‐driven or electric field‐driven?

Dispersion in electroosmotic flow generated by oscillatory electric field interacting with oscillatory wall potentials

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