Mixing with viscoelastic waves at low Reynolds numbers

TL;DR

This paper demonstrates that viscoelastic turbulence in microfluidic channels significantly enhances mixing efficiency at low Reynolds numbers, enabling rapid mixing for chemical and biomedical applications.

Contribution

It introduces the use of viscoelastic turbulence to improve mixing in microfluidic devices, a novel approach for overcoming diffusion limitations without turbulence.

Findings

Viscoelastic turbulence enhances mixing of small molecules and polymers.

It increases reaction rates by folding the solvent through viscoelastic fluctuations.

Optimization strategies improve mixing efficiency and energy use.

Abstract

Mixing at the microfluidic scale is challenging due to the low Reynolds numbers and often high P\'eclet numbers. Without turbulence, mixing relies solely on diffusion, resulting in slow and inefficient mixing. We demonstrate enhanced mixing in a simple Y-shaped microfluidic channel using viscoelastic turbulence in fluids containing macromolecules, suchas DNA and polyethyleneoxide. We investigated mixing at two distinct scales: the mixing of small molecules and the mixing of polymers. We show how the viscoelastic fluctuations fold the solvent, resulting in enhanced reaction rate between two reagents. We also show how the viscoelastic turbulence enhances the mixing of the macromolecules. We discuss optimization strategies taking into account mixing efficiency, mixing time, mixing length and energy efficiency. Viscoelastic turbulence unlocks rapid mixing in microfluidic channels where conventional turbulence cannot operate, offering a versatile platform for applications ranging from chemical synthesis to biomedical assays.