Shear-dependent microvortices in liquid–liquid flow-focusing geometry: A theoretical, numerical, and experimental study

Abstract

In this work, we describe the mechanism of particle trapping and release at the flow-focusing microfluidic droplet generation junction, utilizing the hydrodynamic microvortices generated in the dispersed phase. This technique is based solely on our unique flow-focusing geometry and the flow control of the two immiscible phases and, thus, does not require any on-chip active components. The effectiveness of this technique to be used for particle trapping and the subsequent size selective release into the droplets depends on the fundamental understanding of the nature of the vortex streamlines. Here, we utilized theoretical, computational, and experimental fluid dynamics to study in detail these microvortices and parameters affecting their formation, trajectory, and magnitude.

Validation and Verification of Cavitation in Microchannels by using an Open Source Computational Tool

“…On the other hand, cavity formation within a microchannel can have several applications in particle and cell manipulation due to the vortex formation around them. Some studies in literature focused on forming microvortices within microfluidic channels by utilizing a cavity-like channel geometry for such applications [5][6][7][8][9]. For instance, Kamalakshakurup showed the controlled formation of microvortices to trap microparticles [5], Shen et al studied the circulating particles in microvortices [6], Kim et al utilized the formation of vortices for rapid mixing of reagents in production of hybrid nanoparticles [7], Shen et al showed trapping of particles by using microcavities within a microchannel [8,9].…”

“…Some studies in literature focused on forming microvortices within microfluidic channels by utilizing a cavity-like channel geometry for such applications [5][6][7][8][9]. For instance, Kamalakshakurup showed the controlled formation of microvortices to trap microparticles [5], Shen et al studied the circulating particles in microvortices [6], Kim et al utilized the formation of vortices for rapid mixing of reagents in production of hybrid nanoparticles [7], Shen et al showed trapping of particles by using microcavities within a microchannel [8,9]. Formation of cavity by controlling flow can also be useful for these studies which would eliminate the need for complex geometries.…”