Pumping and mixing in active pores

TL;DR

This paper demonstrates that chemically patterned active pores can function as micro/nano-pumps and mixers through spontaneous symmetry breaking driven by advection, with flow characteristics tunable by geometry and chemistry.

Contribution

It introduces a novel mechanism for fluid pumping and mixing in symmetric pores based on advection-induced symmetry breaking, supported by numerical and analytical analysis.

Findings

Active pores can pump fluids without asymmetry due to spontaneous symmetry breaking.

Flow oscillations with tunable frequency can occur under certain conditions.

Flow symmetry loss enhances mixing at low Reynolds numbers.

Abstract

We show both numerically and analytically that a chemically patterned active pore can act as a micro/nano-pump for fluids, even if it is fore-aft symmetric. This is possible due to a spontaneous symmetry breaking which occurs when advection rather than diffusion is the dominant mechanism of solute transport. We further demonstrate that, for pumping and tuning the flow rate, a combination of geometrical and chemical inhomogeneities is required. For certain parameter values, the flow is unsteady, and persistent oscillations with a tunable frequency appear. Finally, we find that the flow may lose its axial symmetry and hence promotes mixing in the low Reynolds number regime.