Direct measurements of hydrophobic slippage using double-focus fluorescence cross-correlation

Abstract

We report results of direct measurements of velocity profiles in a microchannel with hydrophobic and hydrophilic walls, using a new high precision method of double-focus spacial fluorescence cross-correlation under a confocal microscope. In the vicinity of both walls the measured velocity profiles do not turn to zero by giving a plateau of constant velocity. This apparent slip is proven to be due to a Taylor dispersion, an augmented by shear diffusion of nanotracers in the direction of flow. Comparing the velocity profiles near the hydrophobic and hydrophilic walls for various conditions shows that there is a true slip length due to hydrophobicity. This length, of the order of several tens of nanometers, is independent on electrolyte concentration and shear rate.

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• Boundary slip as a result of a prewetting transition
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Cited by in corpus (34)

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• Electro-osmosis on anisotropic super-hydrophobic surfaces
• Random-roughness hydrodynamic boundary conditions
• Tensorial slip of super-hydrophobic channels
• 'Gas cushion' model and hydrodynamic boundary conditions for superhydrophobic textures
• Transverse flow in thin superhydrophobic channels
• Simulations of slip flow on nanobubble-laden surfaces
• Drag force on a sphere moving towards an anisotropic super-hydrophobic plane
• Anisotropic flow in striped superhydrophobic channels
• Effective slip-length tensor for a flow over weakly slipping stripes
• Flow past superhydrophobic surfaces with cosine variation in local slip length
• Hydrodynamic interaction with super-hydrophobic surfaces
• Transport of ions in hydrophobic nanotubes
• Flows and mixing in channels with misaligned superhydrophobic walls
• Near-wall nanovelocimetry based on Total Internal Reflection Fluorescence with continuous tracking
• Effective hydrodynamic boundary conditions for microtextured surfaces
• Flow in channels with superhydrophobic trapezoidal textures
• Achieving large zeta-potentials with charged porous surfaces
• Slippery and mobile hydrophobic electrokinetics: from single walls to nanochannels
• Boundary conditions at the gas sectors of superhydrophobic grooves
• Studying Flow Close to an Interface by Total Internal Reflection Fluorescence Cross Correlation Spectroscopy: Quantitative Data Analysis
• Statistical mechanical expressions of slip length
• Effective slippage on superhydrophobic trapezoidal grooves
• Lattice-Boltzmann simulations of the drag force on a sphere approaching a superhydrophobic striped plane
• Microscopic determination of macroscopic boundary conditions in Newtonian liquids
• Precursors to Molecular Slip on Smooth Hydrophobic Surfaces
• Advective superdiffusion in superhydrophobic microchannels
• Relation between boundary slip mechanisms and water-like fluid behavior
• Lattice Boltzmann simulations of liquid flilm drainage between smooth surfaces
• Enhanced transport of ions by tuning surface properties of the nanochannel