Acoustic Tweezing and Patterning of Concentration Fields in Microfluidics

TL;DR

This paper presents a theoretical framework for using acoustic forces to manipulate and pattern solute concentration fields in microfluidic systems, enabling stable, controllable configurations and extending acoustic tweezing to concentration manipulation.

Contribution

The authors develop a new theoretical model for acoustic manipulation of concentration fields and demonstrate its application to patterning and tweezing in microfluidics.

Findings

Achieved multi-layer stratification of concentration fields in channels.

Extended acoustic tweezing to manipulate concentration regions.

Demonstrated stable, controllable concentration patterns.

Abstract

We demonstrate theoretically that acoustic forces acting on inhomogeneous fluids can be used to pattern and manipulate solute concentration fields into spatio-temporally controllable configurations stabilized against gravity. A theoretical framework describing the dynamics of concentration fields that weakly perturb the fluid density and speed of sound is presented and applied to study manipulation of concentration fields in rectangular-channel acoustic eigenmodes and in Bessel-function acoustic vortices. In the first example, methods to obtain horizontal and vertical multi-layer stratification of the concentration field at the end of a flow-through channel are presented. In the second example, we demonstrate acoustic tweezing and spatio-temporal manipulation of a local high-concentration region in a lower-concentration medium, thereby extending the realm of acoustic tweezing to include concentration fields.