title: Nonlinear amplification in electrokinetic pumping in nanochannels in the presence of hydrophobic interactions.
abstract: We discover a nonlinear coupling between the hydrophobicity of a charged substrate and electrokinetic pumping in narrow fluidic confinements. Our analyses demonstrate that the effective electrokinetic transport in nanochannels may get massively amplified over a regime of bare surface potentials and may subsequently get attenuated beyond a threshold surface charging condition because of a complex interplay between reduced hydrodynamic resistance on account of the spontaneous inception of a less dense interfacial phase and ionic transport within the electrical double layer. We also show that the essential physics delineated by our mesoscopic model, when expressed in terms of a simple mathematical formula, agrees remarkably with that portrayed by molecular dynamics simulations. The nontrivial characteristics of the initial increment followed by a decrement of the effective zeta potential with a bare surface potential may open up the realm of hitherto-unexplored operating regimes of electrohydrodynamically actuated nanofluidic devices.
authors.affiliation: Department of Mechanical Engineering, Indian Institute of Technology, Kharagpur 721302, India. suman@mech.iitkgp.ernet.in
authors.forename: Suman
authors.initials: S
authors.lastname: Chakraborty
authors.forename: Dipankar
authors.initials: D
authors.lastname: Chatterjee
authors.forename: Chirodeep
authors.initials: C
authors.lastname: Bakli