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Journal Articles New Journal of Physics Year : 2011

Sedimentation of vesicles: from pear-like shapes to microtether extrusion

Manouk Abkarian
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Annie Viallat
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Abstract

We study the sedimentation of buoyant giant lipid vesicles in a quiescent fluid at velocities ranging from 5 to 20 μm/s. Floppy vesicles are deformed by the flow. Their bottom (upstream) part remains spherical while their top (downstream) part narrows down and elongates along the direction of motion, resulting in pear-like shapes or in the reversible formation of a micron-size tube at the vesicle top. The sedimentation velocity of vesicle is very similar to that of a rigid sphere. Using a thermodynamic approach, we show that the hydrodynamic force acting at the top of a floppy vesicle can exceed the critical force needed to draw a membrane tube. We predict that the tube radius scales as the power 1/3 of the ratio of the bending energy to the typical hydrodynamic stress, ηU/R where η is the fluid viscosity, U is the sedimentation velocity and R the vesicle radius. This result is consistent with the reported experimental data. The tensions of vesicles exhibiting a tube and of pear-like shape are deduced from the thermodynamic approach
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Dates and versions

hal-00583690 , version 1 (06-04-2011)

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Huang Zen-Hong, Manouk Abkarian, Annie Viallat. Sedimentation of vesicles: from pear-like shapes to microtether extrusion. New Journal of Physics, 2011, 13, pp.035026. ⟨10.1088/1367-2630/13/3/035026⟩. ⟨hal-00583690⟩
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