The purpose of the recent work is to give a better explanation of how Dean vortices
affect lateral focusing, and to understand how cell morphology can alter the focusing
position compared to spherical particles. The position and extent of the focused region
were investigated using polystyrene fluorescent beads with different bead diameters
(Ø = 0.5, 1.1, 1.97, 2.9, 4.8, 5.4, 6.08, 10.2, 15.8, 16.5 µm) at different flow rates
(0.5, 1, 2 µL/s). Size-dependent focusing generated a precise map of the equilibrium
positions of the spherical beads at the end of the periodically altering channels,
which gave a good benchmark for focusing multi-dimensional particles and cells. The
biological samples used for experiments were rod-shaped Escherichia coli (E. coli),
discoid biconcave-shaped red blood cells (RBC), round or ovoid-shaped yeast, Saccharomyces
cerevisiae, and soft-irregular-shaped HeLa cancer-cell-line cells to understand how
the shape of the cells affects the focusing position at the end of the channel.
