title: Impact of Water-Depletion Layer on Transport in Hydrophobic Nanochannels.
abstract: Recent experiments showed that by fabricating nanofluidic channels with hydrophobic materials, the measured amplitudes of both electroosmotic flow (EOF) and ionic current deviated significantly from the conventional electrokinetic modeling indication. Among these unexpected observations, the complicated dependence of EOF on the surface charge concentration of the channel wall remains most confusing. In this work we give a complete and unified picture for the phenomena by outlining the competing two mechanisms in the water-depletion layer around the channel wall: the decreasing trend of fluidic flow due to the redistribution of net charges, and the increasing trend because of the reduced solution viscosity there. Our quantitative evaluation illustrates that the alternate dominating by the two mechanisms leads to the observed transport behaviors. Furthermore, by considering the decreasing of ionic mobility in the depletion layer, our calculations show quantitative agreement with the latest experiments using BN nanotube channels.
authors.affiliation: School of Optical and Electronic Information, Huazhong University of Science and Technology , LuoYu Road, Wuhan 430074, China.|The Institute of Scientific and Industrial Research, Osaka University , 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Yuhui
authors.initials: Y
authors.lastname: He
authors.affiliation: The Institute of Scientific and Industrial Research, Osaka University , 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Makusu
authors.initials: M
authors.lastname: Tsutsui
authors.affiliation: School of Optical and Electronic Information, Huazhong University of Science and Technology , LuoYu Road, Wuhan 430074, China.
authors.forename: Xiang Shui
authors.initials: XS
authors.lastname: Miao
authors.affiliation: The Institute of Scientific and Industrial Research, Osaka University , 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Masateru
authors.initials: M
authors.lastname: Taniguchi