title: Dynamic superconcentration at critical-point double-layer gates of conducting nanoporous granules due to asymmetric tangential fluxes.
abstract: A transient 10(6)-fold concentration of double-layer counterions by a high-intensity electric field is demonstrated at the exit pole of a millimeter-sized conducting nanoporous granule that permits ion permeation. The phenomenon is attributed to a unique counterion screening dynamics that transforms half of the surface field into a converging one toward the ejecting pole. The resulting surface conduction flux then funnels a large upstream electro-osmotic convective counterion flux into the injecting hemisphere toward the zero-dimensional gate of the ejecting hemisphere to produce the superconcentration. As the concentrated counterion is ejected into the electroneutral bulk electrolyte, it attracts co-ions and produce a corresponding concentration of the co-ions. This mechanism is also shown to trap and concentrate co-ion microcolloids of micron sizes too (macroions) and hence has potential application in bead-based molecular assays.
authors.forename: Shau-Chun
authors.initials: SC
authors.lastname: Wang
authors.forename: Hsien-Hung
authors.initials: HH
authors.lastname: Wei
authors.forename: Hsiao-Ping
authors.initials: HP
authors.lastname: Chen
authors.forename: Min-Hsuan
authors.initials: MH
authors.lastname: Tsai
authors.forename: Chun-Ching
authors.initials: CC
authors.lastname: Yu
authors.forename: Hsueh-Chia
authors.initials: HC
authors.lastname: Chang
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