(168c) Continuous Separation of Plasma From Blood: Cross-Flow Filtration Using a Microsieve

Continuous separation of plasma from whole blood is an essential part of many clinical diagnostic and treatment procedures. With the use of a lithographically well-defined silicon nitride membrane (0.8 μm diameter pores, 750 nm thick) supported on a perforated silicon wafer, human blood was successfully filtered in a microchannel (100 μm height and 5 mm width) in a cross-flow configuration. Trans-membrane pressure (TMP) was monitored during continuous filtration at increasing rates in successive experiments to allow estimation of the maximum sustainable flux. Extensive data under varied conditions, including inlet red cell concentration and plasma shear rate inside the microchannel (determined by flow rate), support the recent model developed by Hill and Leonard [1]. In addition, experimental challenges, such as microsieve sealing and wetting and verification of channel dimensions, are discussed and addressed. Several methods are also proposed to improve the microsieve's performance, including back-pulsation, alteration of pore density, variation of channel configuration upstream of the filter, and microsieve surface treatment.

[1] Hill, M. and Leonard, E.F., "Cross Flow Filtration of a Suspension with Arbitrary Concentration Profile in a Microchannel", submitted, AIChE J, 3/2010 (See also abstract submitted for this session.)