8-9 Jul 2019 Saint Martin d'Heres (France)
Direct Measurement of the Elastohydrodynamic Lift Force at the Nanoscale
Zaicheng Zhang  1@  , Vincent Bertin, Muhammad Arshad, Elie Raphaël  2@  , Thomas Salez  1@  , Abdelhamid Maali  3@  
1 : Laboratoire Ondes et Matière dÁquitaine
Centre National de la Recherche Scientifique : UMR5798, Université de Bordeaux : UMR5798
2 : UMR Gulliver  (Gulliver)  -  Website
CNRS : UMR7083, ESPCI ParisTech
ESPCI - 10 rue Vauquelin - 75231 Paris cedex 05 -  France
3 : Laboratoire Ondes et Matièree d'Aquitaine  (LOMA)
UMR5798 CNRS-Université Bordeaux1

we report on the first direct measurement of the elastohydrodynamic lift force acting on a sphere moving within a viscous liquid, near and along a soft substrate under nanometric confinement. Using atomic force microscopy, the lift force is probed as a function of the gap size, for various driving velocities, viscosities, and stiffnesses. The results are in excellent agreement with scaling arguments and a novel quantitative model developed from the soft lubrication theory, in linear elasticity, and for small compliances. For larger compliances, or equivalently for smaller confinement length scales, a saturation of the lift force is observed and its empirical scaling law is discussed.

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