8-9 Jul 2019 Saint Martin d'Heres (France)
Brownian motion in confinement
Maxime Lavaud  1@  , Pierre Soulard  2@  , Vincent Bertin  1, 2@  , Raphaël Sarfati  3@  , Elie Raphaël  4@  , Yann Louyer  1@  , Thomas Salez  1, 5@  , Yacine Amarouchene  1@  
1 : Laboratoire Ondes et Matière dÁquitaine
Centre National de la Recherche Scientifique : UMR5798
2 : Ecole Supérieure de physique et Chimie Industrielle, laboratoire Gulliver
ESPCI Paris, PSL Research University : UMR7083
3 : Department of Chemical and Biological Engineering [Boulder]
4 : Ecole Supérieure de physique et Chimie Industrielle, laboratoire Gulliver
Centre National de la Recherche Scientifique : UMR7083
5 : Global Station for Soft Matter, Global Institution for Co, Hokkaido University, Sapporo, Hokkaido 060-0808, Japan.

Brownian motion in confinement is a paradigm for numerous biological situations. Here, we study the diffusion of micrometer-sized beads in water confined between two walls that are separated by a micrometric distance. Using holographic microscopy, we track the particles in three dimensions with a precision approaching the nanometric range. From statistical analysis performed on the individual trajectories, we extract the local (i.e. not averaged) diffusion coefficient as a function of the position of the bead in the microcavity. The experimental results are in good agreement with the numerical and analytical predictions — which paves the way towards the study of other situations of confinement.


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