Particle Sorting In a Mini Step-Split-Flow Thin Channel: Influence of Hydrodynamic Shear on Transversal Migration

Abstract

A mini splitterless-split-flow thin fractionation (SPLITT) device has been developed to achieve fast separations of micrometer-sized species. In this device, inlet and outlet steps have replaced the splitters, which are common to conventional SPLITT channels. By elimination of the splitters, it becomes straightforward to reduce channel dimensions while maintaining the classic method of fabrication. Reduced dimension channels allow high axial velocity at relatively low flow rate. These high axial velocities generate an enhancement of inertial lift forces and hydrodynamic shear-induced diffusion. Experiments carried out with particulate and biological species in a mini step-SPLITT channel demonstrate that these hydrodynamic effects yield highly enriched fractions of smaller species from binary mixtures.

Separation of Leishmania-infected macrophages by step-SPLITT fractionation

“…These effects favour a non-specific cross over, i.e. cross-stream migration of particles independently of any external field [6]. Indeed, a few works deal with these important topics and because this study is the first one devoted specifically to macrophages infected with Leishmania, it is not possible to consider a theoretical approach for predicting separations; the complexity of that task deserves a thorough study that is beyond this work.…”

“…The fluidic separation chamber called step-SPLITT channel or s-SPLITT [5,6], is a Hele-Shaw-like cell, i.e. high aspect ratio B/w > 10, with B the breadth and w the thickness, provided with two inlets and two outlets as schematized in Fig.…”

“…However the 70% infection level is only achieved at 24 h post-infection, longer periods are associated with infection level drop and measurements such a nitric oxide production required minimum 48 h post-infection. For this purpose we used the technique called gravitational step-split flow lateral transport thin fractionation (s-SPLITT) [5,6] in order to deplete the population of uninfected cells, from mixtures of uninfected and infected macrophages obtained by primary infection process. The s-SPLITT device is a new development of the classical SPLITT fractionation channel proposed by Giddings [7], which belongs to a family of separation techniques called by Giddings F+ [8].…”

Inertial microfluidics for continuous particle filtration and extraction

“…The randomly dispersed particles at the input align along the microchannel vertical sidewalls and can be filtered using a three-outlet system drag forces due to the curvilinear channel geometries were employed for particle filtration application. The wall-induced lift force-based migration was successfully employed to demonstrate particle separation in a split-flow thin fractionation (SPLITT) device (Callens et al 2008). In traditional SPLITT system, a sheath flow is established near the upper wall of the microchannel, causing particles to migrate across the compressed streamlines based on an external force field (e.g., gravitational).…”

The use of a linear Halbach array combined with a step-SPLITT channel for continuous sorting of magnetic species

“…We present two innovations: 1) the use of a linear Halbach array [6] for generating a very uniform magnetic field and gradient, and 2) the use of a splitterless SPLITT channel, or step-SPLITT channel, [7] having walls thinner than those of conventional channels. Their combination results in the magnetic step-SPLITT device (Mg-s-SPLITT), that is well adapted to high throughput separations and to microfluidic sorting.…”