Anisotropic electro-osmotic flow over super-hydrophobic surfaces

Abstract

Patterned surfaces with large effective slip lengths, such as super-hydrophobic surfaces containing trapped gas bubbles, have the potential to greatly enhance electrokinetic phenomena. Existing theories assume either homogeneous flat surfaces or patterned surfaces with thin double layers (compared to the texture correlation length) and thus predict simple surface-averaged, isotropic flows (independent of orientation). By analyzing electro-osmotic flows over striped slip-stick surfaces with arbitrary double-layer thickness, we show that surface anisotropy generally leads to a tensorial electro-osmotic mobility and subtle, nonlinear averaging of surface properties. Interestingly, the electro-osmotic mobility tensor is not simply related to the hydrodynamic slip tensor, except in special cases. Our results imply that significantly enhanced electro-osmotic flows over super-hydrophobic surfaces are possible, but only with charged liquid-gas interfaces.

10 pages

References in corpus (10)

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Cited by in corpus (22)

• Effective slip in pressure-driven flow past super-hydrophobic stripes
• Wetting, roughness and flow boundary conditions
• Electro-hydrodynamics near Hydrophobic Surfaces
• Electro-osmosis on anisotropic super-hydrophobic surfaces
• Tensorial slip of super-hydrophobic channels
• Effective slip boundary conditions for arbitrary one-dimensional surfaces
• 'Gas cushion' model and hydrodynamic boundary conditions for superhydrophobic textures
• Transverse flow in thin superhydrophobic channels
• Drag force on a sphere moving towards an anisotropic super-hydrophobic plane
• Scaling laws for slippage on superhydrophobic fractal surfaces
• Exact solutions and physical analogies for unidirectional flows
• Effective slip-length tensor for a flow over weakly slipping stripes
• Hydrodynamic interaction with super-hydrophobic surfaces
• Regimes of Wetting Transitions on Superhydrophobic Textures Conditioned by Energy of Receding Contact Lines
• Flow in channels with superhydrophobic trapezoidal textures
• Achieving large zeta-potentials with charged porous surfaces
• Surface and zeta potentials of charged permeable nanocoatings
• Growth morphology and symmetry selection of interfacial instabilities in anisotropic environments
• Effect of Electro-Osmotic Flow on Energy Conversion on Superhydrophobic Surfaces
• An electrokinetic route to giant augmentation in load bearing capacity of compliant microfluidic channels
• Effect of Ionic Advection on Electroosmosis over Charge Modulated Surfaces: Beyond the Weak Field Limit
• A multi-scale model for electrokinetic transport in networks of micro-scale and nano-scale pores