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dc.contributor.authorBazant, Martin Z.
dc.contributor.authorKilic, Mustafa Sabri
dc.contributor.authorStorey, Brian D.
dc.contributor.authorAjdari, Armand
dc.date.accessioned2012-02-15T14:06:01Z
dc.date.available2012-02-15T14:06:01Z
dc.date.issued2009-10
dc.identifier.issn0001-8686
dc.identifier.urihttp://hdl.handle.net/1721.1/69106
dc.description.abstractThe venerable theory of electrokinetic phenomena rests on the hypothesis of a dilute solution of point-like ions in quasi-equilibrium with a weakly charged surface, whose potential relative to the bulk is of order the thermal voltage (kT/e ≈ 25 mV at room temperature). In nonlinear electrokinetic phenomena, such as AC or induced-charge electro-osmosis (ACEO, ICEO) and induced-charge electrophoresis (ICEP), several V ≈ 100 kT/e are applied to polarizable surfaces in microscopic geometries, and the resulting electric fields and induced surface charges are large enough to violate the assumptions of the classical theory. In this article, we review the experimental and theoretical literatures, highlight discrepancies between theory and experiment, introduce possible modifications of the theory, and analyze their consequences. We argue that, in response to a large applied voltage, the “compact layer” and “shear plane” effectively advance into the liquid, due to the crowding of counterions. Using simple continuum models, we predict two general trends at large voltages: (i) ionic crowding against a blocking surface expands the diffuse double layer and thus decreases its differential capacitance, and (ii) a charge-induced viscosity increase near the surface reduces the electro-osmotic mobility; each trend is enhanced by dielectric saturation. The first effect is able to predict high-frequency flow reversal in ACEO pumps, while the second may explain the decay of ICEO flow with increasing salt concentration. Through several colloidal examples, such as ICEP of an uncharged metal sphere in an asymmetric electrolyte, we show that nonlinear electrokinetic phenomena are generally ion-specific. Similar theoretical issues arise in nanofluidics (due to confinement) and ionic liquids (due to the lack of solvent), so the paper concludes with a general framework of modified electrokinetic equations for finite-sized ions.en_US
dc.description.sponsorshipNational Science Foundation (U.S.) (contract DMS-0707641)en_US
dc.language.isoen_US
dc.publisherElsevieren_US
dc.relation.isversionofhttp://dx.doi.org/10.1016/j.cis.2009.10.001en_US
dc.rightsCreative Commons Attribution-Noncommercial-Share Alike 3.0en_US
dc.rights.urihttp://creativecommons.org/licenses/by-nc-sa/3.0/en_US
dc.sourceProf. Bazant via Erja Kajosaloen_US
dc.titleTowards an understanding of induced-charge electrokinetics at large applied voltages in concentrated solutionsen_US
dc.typeArticleen_US
dc.identifier.citationBazant, Martin Z. et al. “Towards an understanding of induced-charge electrokinetics at large applied voltages in concentrated solutions.” Advances in Colloid and Interface Science 152.1-2 (2009): 48-88.en_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Chemical Engineeringen_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Mathematicsen_US
dc.contributor.approverBazant, Martin Z.
dc.contributor.mitauthorBazant, Martin Z.
dc.contributor.mitauthorKilic, Mustafa Sabri
dc.relation.journalAdvances in Colloid and Interface Scienceen_US
dc.eprint.versionAuthor's final manuscripten_US
dc.type.urihttp://purl.org/eprint/type/JournalArticleen_US
eprint.statushttp://purl.org/eprint/status/PeerRevieweden_US
dspace.orderedauthorsBazant, Martin Z.; Kilic, Mustafa Sabri; Storey, Brian D.; Ajdari, Armanden
mit.licenseOPEN_ACCESS_POLICYen_US
mit.metadata.statusComplete


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