(416a) Separation of Plasma From Blood by Crossflow Filtration through Nanoporous Filters From a Microchannel

Current theories of crossflow filtration assume the existence of a bulk flow of uniform concentration from which particles are filtered through a thin boundary layer at the wall. Crossflow filtration from a microchannel strains this assumption, as the boundary layer will fill the entire microchannel. This is further complicated if one wishes to use layered flows of differing composition in the microchannel; then a single bulk concentration does not exist. The use of nanoporous filters with low flow resistance adds to the complexity, as the pressure drop down the microchannel needs to be balanced against the pressure drop across the filter to avoid backflow of filtrate.

A model of steady crossflow filtration from a microchannel through nanoporous filters at low Reynolds numbers was developed, showing the effect of inlet concentration distribution, dimensionless filter length and Peclet number. This model is currently proving useful in the design of a microfluidic membraneless artificial kidney which must be able to separate plasma from blood at high flows.