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Drops, vesicles and red blood cells: Deformability and behavior under flow

Abstract : Drops, vesicles and red blood cells are soft, deformable, structured and micron-size (1-100 microns in diameter) objects. This objective of this work is the determination of the participation of each mechanical property of the objects studied (surface tension, elasticity, viscosity...) from their behavior under flow. We looked more precisely at the response of these objects under confined (or semi-confined) flow using a microfluidic approach.
The production of surfactant at the interface of a drop flowing influences its shape and its dynamics. The study details among other things, the effects of surfactant concentration and device geometry.
The production of vesicles with complex mechanical properties tunable by action of the temperature is presented. We also investigate the impact of the sol/gel transition of DMPC lipid membrane on their behavior under external strss (osmotic pressure, flow...)
In the case of red blood cells under shear flow, two types of motion are known : the tumbling motion and the tank-treading motion. We highlight a new feature of the tank-treading motion, the particle oscillates periodically. We also studied the behavior of red blood cells flowing in close-fitting capillaries. We establish a shape diagram versus the speed of the object, the external viscosity and the dimensions of the capillary. We have developed a system able to measure the pressure drop associated to the flow of a unique cell in a close fitting channel. This measurement allows the correlation of the signal obtained with the mechanical properties of the objects. We illustrate this approach with red and white blood cells. Finally, we studied the pathologic case of the thrombosis with a concentrated suspension of cells.
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Contributor : Magalie Faivre <>
Submitted on : Wednesday, January 24, 2007 - 6:42:38 PM
Last modification on : Friday, January 18, 2019 - 2:36:18 PM
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  • HAL Id : tel-00126365, version 1




Magalie Faivre. Drops, vesicles and red blood cells: Deformability and behavior under flow. Biological Physics []. Université Joseph-Fourier - Grenoble I, 2006. English. ⟨tel-00126365⟩



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