Scale invariant hydrodynamic focusing and sorting of inertial particles by size in spiral micro channels

Abstract

The hydrodynamic separation of spherical particles in flows at low Reynolds numbers is a very active area of research in microfluidic engineering due to the many important biomedical applications. In particular, curved channels such as spiral channels are of growing interest because the lift and drag force exerted on inertial particles can be used to hydrodynamically separate the particles. In this paper we present a scale invariant classification of the lateral focusing of particles in highly curved spiral micro channels with a square cross section. We then use this scale invariant classification to demonstrate the separation of particles in two-particle mixtures across a large range of sizes. We thus show that our results can be used to systematically design the geometry of devices and select flow parameters to separate particles by size in a mixture.

Limitation of spiral microchannels for particle separation in heterogeneous mixtures: Impact of particles’ size and deformability

“…Separation and sorting of cells is an important bioprocess across medical, environmental and biotechnology applications, where existing technologies like centrifugation and filtration have several drawbacks [1][2][3]. Microfluidic approaches to cell sorting and separation can be divided into active, which exploit external forces e.g., electrical, acoustic, optical or magnetic fields, and passive, which utilise channel geometry and hydrodynamic forces [4].…”

On the Three-Dimensional Structure of the Flow through Deterministic Lateral Displacement Devices and Its Effects on Particle Separation

“…In this case, microfluidics-assisted processes are typically used for separating and sorting the dispersed phase based on some physical feature of the particles (e.g., size, electric charge, shape and so on). In certain regimes, quantified by sufficiently large values of the particle Reynolds number Re p = ρ u − v /µ (ρ, µ and u being the density, viscosity and local velocity of the supending fluid, respectively, and v being the instantaneous particle velocity), the transport features of the embedded particles can be controlled exploiting their inertia, which makes them deviate from the streamlines of the underlying suspending flow [9,10]. At vanishing values of Re p , that is, in the the overdamped regime [11], particles tend to trace over the streamlines of the carrier flow and approaches alternative to inertial effects must be used to control their motion.…”

Recent Advances and Future Perspectives on Microfluidic Liquid Handling

“…For both diagnostic and therapeutic purposes, high-throughput label-free microfluidic cell sorters are in great demand. Using the passive hydrodynamic approach, Tallapragada et al [ 87 ] proposed a scale-independent method to separate and encapsulate inertial particles, specifically pancreatic islets, in serpentine microchannels. Finally, microfluidic chromatographic platforms have also opened up new avenues for separation chemistry, especially for protein purification [ 88 ].…”