FIG. 1.

Schematic illustration of particle focusing in flow through curved channels. Randomly distributed particles are first affected by dominant lift forces in the straight channel. In this section, the particles start to focus vertically along the height of the channel. When the particles enter the curvature, counter rotating Dean vortices will force the particles to occupy a single lateral focusing point (xf) when exiting the curvature. Inset: Cross-section of the channel showing the presence of Dean vortices and how the dominant forces acting on a particle forcing it to focus in a distinct lateral position exiting the curved channel. Among the lift forces in flow through low aspect ratio, the vertical lift forces dominate and will tend to focus particles vertically on top and bottom while the Dean forces then move participles towards the lateral focusing position.