Separations of spherical and disc-shaped polystyrene particles and blood components (red blood cells and platelets) using pinched flow fractionation device with a tilted sidewall and vertical focusing channels (t-PFF-v)

Shape-based separation capabilities of a novel pinched flow fractionation device with a tilted sidewall and vertical focusing channels (t-PFF-v) were demonstrated for (1) spherical and disc-shaped polystyrene (PS) particles; (2) platelets (PLT) and red blood cells (RBC); and (3) singlet, doublet, and triplet clusters of disc-shaped PS particles. The tilted sidewalls and vertical focusing channels of the t-PFF-v device allowed us to perform enhanced separation of non-spherical particles. Using this t-PFF-v device with a Wp (pinched segment width) of 20 μm and 15 μm, not only spherical (diameter of 2 μm) and disc-shaped (thickness of ∼2 μm, diameter of ∼5.0 μm) PS particles but also PLTs and RBCs from diluted blood were well separated with good separation resolutions (Rdisc,sphere = 1.40 and RPLT,RBC = 1.28). Additionally, time-lapse images of flowing particles indicated that both disc-shaped PS particles and RBCs are probably having type I orientation in the pinched segment (i.e., leaning against the tilted sidewalls at the pinched segment). Moreover, we observed streamlines of singlet, doublet, and triplet clustered disc-shaped PS particles, which suggested that these clustered particles could be well separated according to their aspect ratio. The doublet or triplet clustered PS particles are probably lay on the floor and rotated at the pinched segment (type II orientation). We believe that this shape-based separation capability achieved by the t-PFF-v device can be utilized for many application areas, such as medical, biological, material and colloidal sciences.