Controlling sample and particle behaviour in microfluidic systems using acoustic forces

Abstract

Acoustic forces have been widely used to control microparticles within microfluidic systems. Such acoustofluidic systems have been very successful in tasks such as cell sorting, however, to date efforts have been mostly limited to single phase systems. Just as the contrast in acoustic impedance between a fluid and suspended particle means that acoustic forces can be exerted on the particle, a contrast also exists at the interface between two immiscible fluids. This work explores ways in which such acoustically generated forces can be used in digital (two phase) microfluidic systems. Digital microfluidic systems have gathered significant interest because of the potential of single cell analysis and on-chip chemical reactions. In the paradigm of a lab-on-a-chip, each droplet is analogous to a test tube; however, due to the rapidity of producing large numbers of droplets, reaction based systems can run into difficulties as each test tube contains the same sample. In order to gain control over droplet behavio...