The internal flow in an evaporating human blood plasma drop

Area of Science:

• Fluid dynamics
• Biophysics
• Biochemistry

Background:

• Evaporation-driven flows in sessile drops are crucial in biological and industrial processes.
• Blood plasma evaporation exhibits distinct internal flow dynamics compared to simple liquids like water.
• Plasma proteins at the interface significantly influence surface tension gradients and flow behavior.

Purpose of the Study:

• To visualize and understand the real-time internal fluid flow within an evaporating blood plasma drop.
• To elucidate the mechanism of natural convection and its role in plasma drop evaporation.
• To investigate how different plasma proteins affect Marangoni flow suppression.
• To analyze the combined effects of natural convection and capillary flow on material transport and desiccation patterns.

Main Methods:

• Real-time observation of internal flow in evaporating plasma drops.
• Numerical simulations to support experimental findings on natural convection.
• Comparative studies on Marangoni flow suppression by various plasma proteins.
• Analysis of the interplay between capillary flow and natural convection.

Main Results:

• Natural convection within evaporating plasma drops was experimentally observed and numerically validated.
• Plasma proteins were identified as the cause of Marangoni flow suppression, differentiating plasma from water evaporation.
• Varying efficiencies of Marangoni convection suppression were noted among different plasma proteins.
• The synergistic interaction between capillary flow and natural convection governs material transport and the final dried pattern.

Conclusions:

• The unique desiccation patterns of blood plasma drops result from the interplay between natural convection and capillary flow, driven by Marangoni flow suppression.
• Understanding these fluid dynamics is key to controlling material deposition and pattern formation in biological samples.