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Micro Total Analysis System (µTAS) devices frequently need to deal with bio-particle suspensions in solution and separation of certain bio-particles is often desirable. Separation of plasma from the whole blood has become increasingly popular in clinical diagnostics. Using a finite volume method, Volume of Fluid (VOF) and Discrete Phase (DP) governing equations for multiphase flow are used to delineate the effect of non-Newtonian shear-thinning viscosity of blood from Newtonian viscosity of water. It is observed that the Red Blood Cells (RBC) accumulate at the front of the blood column due to the effect of non-Newtonian viscosity, while the opposite is observed in water. For the selected parameters, 20% of the plasma is observed to be separated from the whole blood, while, in contrast, for a 98% diluted blood 45% of the plasma can be separated. Increase in the particle density and size has resulted in a better separation of the beads from the water for a given magnitude of pressure and number of pulses. For a given pressure, increasing the number of pressure pulses provides more separation and with a low number of applied pulses, higher pressures provide better separation. The present calculations can be adopted to design the flow parameters necessary for the instantaneous separation of plasma from the whole and the diluted blood for µTAS; thus reducing the number of experimental studies. The present method can also be used for calculating the separation of other bio-particles in aqueous solutions. |
