Figure 2
From: High-Reynolds Microfluidic Sorting of Large Yeast Populations
Microfluidic high Reynolds inertial sorting (A) Analytical calculation of shear-induced lift forces acting on 15 μm particle, in a horizontal cross-section of a rectangular channel, as previously shown14. Stable equilibrium points are indicated by black arrows. Numerically derived velocity profile is superimposed. (B) Illustration of centrifugal forces acting on a dense 4 μm particle exposed to two Dean vortices. Stable equilibrium point indicated by black arrows. (C) Long-exposure images of fluorescent beads focused in curved microfluidic channels with 0.9 mm radius of curvature. Inertia focusing predominates in large particles, pushing beads to the concave side of the channel, while Dean vortices traps small particles in the center of the channel. Particle size threshold for inertial focusing increases with fluid velocity. (D,E) Cytometry-based particle analysis of microfluidic outflow compared to unsorted particle mixture. Particles were isolated at 1.5 mL/min flow rate (Re = 215). High purity of small 4.1 μm particles was obtained at convex side (outlet 1) but at low 12 ± 1% yield. Small 4.1 μm particles were primarily focused by Dean vortices to the channel center (outlet 2) with a yield of 55 ± 5%. Purity of 4.1 μm ranged from 79 ± 1% compared to similarly sized 5.56 μm particles, with overlapping distribution (D) to 97 ± 1% when separated from larger 9.95 μm particles (E). Large 5.56 and 9.95 μm particles were primarily pushed toward the concave side of the channel (outlet 4) by opposing shear-induced forces. Purity of larger particles ranged from 76 ± 9% to 90 ± 5% for 9.95 μm and 5.56 μm particles, respectively, with similar yields of 60 ± 9%. (F) Long exposure image of 4.1 μm (green) and 5.56 μm (red) particle streaklines. The green particles are focused to the center of the channel, and red particles are primarily pushed toward the concave edge of the channel. (G) Long exposure image of a heterogeneous yeast sample (blue). The streakline’s highest intensity location (white histogram) coincides with the small bead streakline (4.1 μm, green arrow) rather than the large bead streakline (5.56 μm, red arrows). (H) Photo of the microfluidic device composed of 4 repeats of curved microfluidic channels.
