High-speed imaging determines fluid dynamics of blood plasma

Using high-speed cameras, researchers at Saarland University (www.uni-saarland.de) and the University of Pennsylvania (www.upenn.edu) have shown that the plasma in blood is a non-Newtonian fluid.

Until recently, it had been assumed that the non-Newtonian characteristics exhibited by blood were mainly due to the presence of the red blood cells, which account for about 45% of the blood's volume. Previously, blood plasma was generally regarded as playing no active role; researchers had assumed that since it contains about 92% water, it would behave in a similar fashion.

Saarland University experimental physicist and professor Christian Wagner and professor Paulo E. Arratia of the University of Pennsylvania showed this was not the case after studying the flow dynamics of blood.

At Saarland University, experiments were conducted in which blood plasma was placed between two plates and the plates drawn apart. High-speed M3 series cameras from IDT (www.idtpiv.com), fitted with CFI Plan Achromat microscope lenses from Nikon Instruments (www.nikoninstruments.com) attached via an InfiniTube system from Edmund Optics (www.edmundoptics.com), captured the formation of threads and drops at 2128 frames/sec, demonstrating that blood plasma exhibits both viscous and elastic behavior when deformed; the fluid dynamics prove that the plasma deviates from the behavior of water.

Wagner's team also showed that blood plasma influences the creation of vortices in flowing blood. These vortices may facilitate the formation of deposits on blood vessel walls, which could influence blood-clot formation.

In one of the experiments, the research team let plasma flow through a narrow channel of the kind found in constricted arteries or in a stent. Vortices were detected at both the end and the entrance of the narrow channel, and their formation was determined to be a direct result of the viscoelastic flow properties of the blood plasma.