Membrane plasma separation through small-area, hollow-fiber filters

Area of Science:

• Biomedical Engineering
• Fluid Dynamics
• Materials Science

Background:

• Small polypropylene hollow-fiber plasma filters are crucial for various medical applications.
• Understanding filtration capabilities and hemolysis risk is essential for optimizing filter design and performance.

Purpose of the Study:

• To investigate the filtration capabilities of small polypropylene hollow-fiber plasma filters.
• To determine the relationship between filtration flux, shear rate, and filter geometry.
• To assess the conditions under which hemolysis occurs and how to prevent it.

Main Methods:

• Experimental investigation of plasma filters with membrane areas from 100 to 1,000 cm2.
• Measurement of filtration flux and transmembrane pressure.
• Analysis of the effect of wall shear rate (gamma w) and fiber length (L) on filtration performance.

Main Results:

• Filtration flux per unit membrane area is approximately proportional to the wall shear rate up to 7,500 s-1.
• Total filtration flow rate increases with fiber length (L^2/3) but shows minimal increase with more fibers due to decreased shear rate.
• Hemolysis threshold increases with shear rate, allowing high blood flow rates in small filters (100 cm2) if fiber length is below a critical value.

Conclusions:

• Filter design can be optimized by balancing membrane area, fiber length, and shear rate to maximize filtration flow.
• Controlling transmembrane pressure and optimizing fiber length in conjunction with shear rate can prevent hemolysis.
• Small-scale hollow-fiber plasma filters can achieve high blood flow rates safely by managing shear rate and fiber dimensions.