Dispersion control in pressure-driven flow through bowed rectangular microchannels

TL;DR

This study demonstrates how deforming the upper wall of a rectangular microchannel can control dispersion in pressure-driven flow, aligning experimental results with theoretical predictions to optimize flow characteristics.

Contribution

It introduces a novel method for manipulating dispersion in microchannels through controlled wall deformation, validated by experiments and numerical models.

Findings

Optimal deformation reduces dispersion at specific aspect ratios.

Experimental results agree with numerical and theoretical predictions.

Wall deformation significantly influences solute spreading in microchannels.

Abstract

In fully-developed pressure-driven flow, the spreading of a dissolved solute is enhanced in the flow direction due to transverse velocity variations in a phenomenon now commonly referred to as Taylor-Aris dispersion. It is well understood that the characteristics of the dispersion are sensitive to the channel's cross-sectional geometry. Here we demonstrate a method for manipulation of dispersion in a single rectangular microchannel via controlled deformation of its upper wall. Using a rapidly prototyped multi-layer microchip, the channel wall is deformed by a controlled pressure source allowing us to characterize the dependence of the dispersion on the deflection of the channel wall and overall channel aspect ratio. For a given channel aspect ratio, an optimal deformation to minimize dispersion is found, consistent with prior numerical and theoretical predictions. Our experimental measurements are also compared directly to numerical predictions using an idealized geometry.