AC Electroosmotic Pumping in Nanofluidic Funnels

Kneller, Andrew R.; Haywood, Daniel G.; Jacobson, Stephen C.

doi:10.1021/acs.analchem.6b00839

Cited by 26 publications

(24 citation statements)

References 34 publications

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“…EFR was first demonstrated using pyramidal pore mica membranes [ 31 , 32 ]. Later studies have shown EFR in conical pore polymeric membranes [ 33 ] and photolithographed nanotunnels [ 34 ].…”

Section: Introductionmentioning

confidence: 99%

From Ion Current to Electroosmotic Flow Rectification in Asymmetric Nanopore Membranes

Experton

Martin

2017

Nanomaterials

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Asymmetrically shaped nanopores have been shown to rectify the ionic current flowing through pores in a fashion similar to a p-n junction in a solid-state diode. Such asymmetric nanopores include conical pores in polymeric membranes and pyramidal pores in mica membranes. We review here both theoretical and experimental aspects of this ion current rectification phenomenon. A simple intuitive model for rectification, stemming from previously published more quantitative models, is discussed. We also review experimental results on controlling the extent and sign of rectification. It was shown that ion current rectification produces a related rectification of electroosmotic flow (EOF) through asymmetric pore membranes. We review results that show how to measure and modulate this EOF rectification phenomenon. Finally, EOF rectification led to the development of an electroosmotic pump that works under alternating current (AC), as opposed to the currently available direct current EOF pumps. Experimental results on AC EOF rectification are reviewed, and advantages of using AC to drive EOF are discussed.

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Section: Introductionmentioning

confidence: 99%

From Ion Current to Electroosmotic Flow Rectification in Asymmetric Nanopore Membranes

Experton

Martin

2017

Nanomaterials

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“…The required asymmetry occurs, for example, in nano-funnels, 12 or in tracketched membranes with conical nano-pores, [13][14][15] and, indeed, net ACEO pumping has been demonstrated experimentally for such systems. However, for the concentration polarization to be sufficiently strong, the smallest dimension of the nano-channel cannot be too large compared to the Debye screening length, otherwise the concentration polarization is "suppressed" by electroosmosis itself.…”

Section: Introductionmentioning

confidence: 96%

Asymmetric electroosmotic pumping across porous media sandwiched with perforated ion-exchange membranes

et al. 2017

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To have non-zero net flow in AC electroosmotic pumps, the electroosmosis (EO) has to be non-linear and asymmetric. This can be achieved due to ionic concentration polarization. This is known to occur close to micro-/nano-interfaces provided that the sizes of the nanopores are not too large compared to the Debye screening length. However, operation of the corresponding EO pumps can be quite sensitive to the solution concentration and, thus, unstable in practical applications. Concentration polarization of ion-exchange membranes is much more robust. However, the hydraulic permeability of the membrane is very low, which makes EO flows through them extremely small. This communication shows theoretically how this problem can be resolved via making scarce microscopic perforations in an ion-exchange membrane and putting it in series with an EO-active nano-porous medium. The problem of coupled flow, concentration and electrostatic-potential distributions is solved numerically by using finite-element methods. This analysis reveals that even quite scarce perforations of micron-scale diameters are sufficient to observe practically-interesting EO flows in the system. If the average distance between the perforations is smaller than the thickness of the EO-active layer, there is an effective homogenization of the electrolyte concentration and hydrostatic pressure in the lateral direction at some distance from the interface. The simulations show this distance to be somewhat lower than the half-distance between the perforations. On the other hand, when the surface fraction of perforations is sufficiently small (below a fraction of a percent) this "homogeneous" concentration is considerably reduced (or increased, depending on the current direction), which makes the EO strongly non-linear and asymmetric. This analysis provides initial guidance for the design of high-productivity and inexpensive AC electroosmotic pumps.

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“…Nanofluidics is a branch of fluid mechanics that deals with fluid flow and transport phenomena through nanoscale geometries and has lots of applications in medicine, biology, genetics, material science, and energy conversion technologies [1][2][3][4][5][6][7][8][9][10]. Electrokinetic phenomena are wildly used in nanofluidic devices to perform many tasks such as generating flow field in nanochannels [11][12][13], transport of ions [13][14][15], and manipulating DNAs in the nanoconfinements [16]. The electrokinetics will also affect cell membrane transport through natural or artificial nanopores created on cell membranes [7][8][9]17].…”

Section: Introductionmentioning

confidence: 99%

An improved hybrid continuum‐atomistic four‐way coupled model for electrokinetics in nanofluidics

2019

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In this study, an efficient hybrid continuum‐atomistic method is proposed to study electrokinetic transport of aqueous solutions in nanofluidics. The aqueous phase is considered as a continuous phase containing immersed ion particles. The behavior of the system is then simulated through utilization of an improved hybrid continuum‐atomistic four‐way coupled approach, including the MultiPhase Particle‐In‐Cell method for the short‐ranged interaction between the ion particles, the Brownian force for the collision between the aqueous phase molecules and the ion particles, and a wall force accounting for the short‐ranged interaction of ions and walls. The validation of the proposed model with the results of Molecular Dynamics simulations suggests that this model can be a promising approach for studying the electrokinetic phenomena in more complicated geometries where the Molecular Dynamics approach is computationally prohibitive. Finally, the effects of electrokinetic parameters, such as the height of the channel, the external electric field, and bulk ionic concentration, on the electroosmotic flow in a nanochannel are investigated and discussed.

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AC Electroosmotic Pumping in Nanofluidic Funnels

Cited by 26 publications

References 34 publications

From Ion Current to Electroosmotic Flow Rectification in Asymmetric Nanopore Membranes

From Ion Current to Electroosmotic Flow Rectification in Asymmetric Nanopore Membranes

Asymmetric electroosmotic pumping across porous media sandwiched with perforated ion-exchange membranes

An improved hybrid continuum‐atomistic four‐way coupled model for electrokinetics in nanofluidics

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