Plasma filtration in Couette flow membrane devices.

Area of Science:

• Biomedical Engineering
• Fluid Dynamics
• Membrane Science

Background:

• Plasma separation from whole blood is crucial for various medical applications.
• Conventional methods like hollow fiber filters have limitations in filtration efficiency.
• Rotating membrane devices offer a potential alternative for improved blood component separation.

Purpose of the Study:

• To investigate the performance of a rotating membrane device for plasma separation.
• To determine the effects of transmembrane pressure (ptm), rotation speed, and membrane characteristics on filtration velocity.
• To elucidate the underlying mechanisms responsible for high filtration rates.

Main Methods:

• A rotating membrane device with a 58 cm2 polymeric membrane was utilized.
• The device generated Couette flow within a 0.9 mm gap at rotation speeds of 3,000-4,000 r/min.
• Experiments were conducted using polycarbonate and nylon membranes with varying pore sizes and transmembrane pressures.

Main Results:

• Maximum filtration velocities ranged from 0.5-0.8 cm/min, 10-20 times higher than hollow fiber filters.
• High performance was attributed to shear rates (approx. 20,000 sec-1) generated by Taylor vortices.
• Filtration velocity showed distinct responses to transmembrane pressure depending on membrane pore size and material.

Conclusions:

• Rotating membrane devices with high shear rates offer superior plasma filtration performance.
• Taylor vortices are the primary mechanism for enhanced filtration, surpassing centrifugal effects.
• Membrane characteristics and operating conditions, such as transmembrane pressure, critically influence device efficacy.