Cross-Sectional Distributions of Platelet-Sized Particles in Blood Flow through Microchannels

Abstract

In blood flow through microvessels, platelets are known to have enhanced concentrations near the vessel wall, which is the so-called “near-wall excess”. In the present study, the spatial distribution of platelet-sized polystyrene particles in red cell suspension flowing through microchannels with a square cross-section of 50 μm width was measured by a confocal laser scanning microscope. The measurements were performed at the flow rate of 1.0 μL/min for various particle diameters (d = 1.0 - 4.8 μm) and various volume fractions of red cells (hematocrit; Hct = 0 - 40 %). In the absence of red cells, the particles were uniformly distributed in the channel cross-section. For all cases studied, their distributions were also uniform at the inlet of the channel. At downstream cross-sections, high concentrations of particles near the channel wall were obtained in the presence of red cells. This tendency was enhanced for higher hematocrits and larger particles. The cross-sectional distribution of the particles revealed enhanced particle probability near the channel corners rather than near the center of the channel faces, suggesting that the particles are focused mainly close to the corners due to the square cross-section of the channel.