title: Capillary force on a micrometric sphere trapped at a fluid interface exhibiting arbitrary curvature gradients.
abstract: We report theoretical predictions and measurements of the capillary force acting on a spherical colloid smaller than the capillary length that is placed on a curved fluid interface of arbitrary shape. By coupling direct imaging and interferometry, we are able to measure the in situ colloid contact angle and to correlate its position with respect to the interface curvature. Extremely tiny capillary forces down to femtonewtons can be measured with this method. Measurements agree well with a theory relating the capillary force to the gradient of Gaussian curvature and to the mean curvature of the interface prior to colloidal deposition. Numerical calculations corroborate these results.
authors: Université Montpellier 2, Laboratoire Charles Coulomb, UMR 5521, F-34095 Montpellier Cedex 5, France.
authors: Christophe
authors: C
authors: Blanc
authors: Denys
authors: D
authors: Fedorenko
authors: Michel
authors: M
authors: Gross
authors: Martin
authors: M
authors: In
authors: Manouk
authors: M
authors: Abkarian
authors: Mohamed Amine
authors: MA
authors: Gharbi
authors: Jean-Baptiste
authors: JB
authors: Fournier
authors: Paolo
authors: P
authors: Galatola
authors: Maurizio
authors: M
authors: Nobili
mesh_terms: D003102:Colloids / Q000737:chemistry*; D007368:Interferometry / Q000379:methods; D008956:Models, Chemical; D013500:Surface Tension
chemical_list: D003102:Colloids