Geometric pumping in autophoretic channels

TL;DR

This paper demonstrates that channel geometry alone can induce and control net flow in microfluidic channels via autophoretic effects, without the need for chemical patterning, supported by numerical and analytical analysis.

Contribution

It reveals that geometric design alone can drive autophoretic flow in microchannels, eliminating the need for chemical patterning of the walls.

Findings

Channel geometry alone can generate net flow.

Flow rate depends on geometric characteristics.

Analytical and numerical results are consistent.

Abstract

Many microfluidic devices use macroscopic pressure differentials to overcome viscous friction and generate flows in microchannels. In this work, we investigate how the chemical and geometric properties of the channel walls can drive a net flow by exploiting the autophoretic slip flows induced along active walls by local concentration gradients of a solute species. We show that chemical patterning of the wall is not required to generate and control a net flux within the channel, rather channel geometry alone is sufficient. Using numerical simulations, we determine how geometric characteristics of the wall influence channel flow rate, and confirm our results analytically in the asymptotic limit of lubrication theory.