Transverse flow in thin superhydrophobic channels

TL;DR

This paper provides theoretical guidelines for optimizing transverse flow in superhydrophobic channels with textured surfaces, aiming to enhance microfluidic mixing and electrokinetic effects.

Contribution

It introduces a theoretical framework for maximizing transverse flow by optimizing surface texture parameters in superhydrophobic channels.

Findings

Strong transverse flows achievable with aligned striped surfaces

Optimization of slip lengths and pattern orientations enhances flow

Potential applications in microfluidic mixing and electrokinetics

Abstract

We provide some general theoretical results to guide the optimization of transverse hydrodynamic phenomena in superhydrophobic channels. Our focus is on the canonical micro- and nanofluidic geometry of a parallel-plate channel with an arbitrary two-component (low-slip and high-slip) coarse texture, varying on scales larger than the channel thickness. By analyzing rigorous bounds on the permeability, over all possible patterns, we optimize the area fractions, slip lengths, geometry and orientation of the surface texture to maximize transverse flow. In the case of two aligned striped surfaces, very strong transverse flows are possible. Optimized superhydrophobic surfaces may find applications in passive microfluidic mixing and amplification of transverse electrokinetic phenomena.