Cross-Flow Filtration of Plasma From Blood From a Microchannel

Wednesday, October 19, 2011: 9:20 AM
203 B (Minneapolis Convention Center)
Xiangnan Ye1, Levy Amar1, Michael Hill1, James Jones2, Jacob Baggerman3, Cees van Rijn3 and Edward F. Leonard1, (1)Chemical Engineering, Columbia University, New York, NY, (2)Department of Medicine -- St. Lukes'/Roosevelt Hospital, Columbia University, New York, NY, (3)Aquamarijn Micro Filtration, Zutphen, Netherlands

Steady cross-flow filtration of plasma through microsieves from blood in a microchannel is an important part of several biomedical applications under development, including a new artificial kidney.  Erythrocytes, which comprise the largest volume fraction of all particulates in blood, are believed to create the controlling resistance at the sieve surface.  Maximum steady-state filtration flux has been observed to be a function of wall shear rate, as predicted by any conventional cross-flow filtration theory, but to show weak dependence on erythrocyte concentration, contrary to theory based on convective diffusion.  Maximum filtration flux has also been observed to be a function of sieve pore size and shape (in spite of their very low flow resistance) as well as sieve surface coating.  

Recent experiments have correlated macroscopic measurements (filtration rates, transmembrane pressures) with direct observation of erythrocyte behavior at the filtering surface.  At low filtration rates (low transmembrane pressures), erythrocytes roll across the filter surface, but at higher filtration rates (higher transmembrane pressures), erythrocytes are observed sticking to the sieve surface.  Post-filtration SEM’s, even those obtained at very low transmembrane pressures, reveal significant capture and deformation of erythrocytes in the filter pores.  Careful balances among sieve design (which can be precisely defined by photolithography), surface treatments of sieves, and flow conditions, allow filtration fluxes at rates exceeding 0.1 cm3/cm2-min.

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See more of this Session: Theories and Applications of Cross Flow Filtration
See more of this Group/Topical: Separations Division