The description of hydrodynamic interactions between a particle and the surrounding liquid, down to the nanometer scale, is of primary importance since confined liquids are ubiquitous in many natural and technological situations. In this paper we combine three nonconventional atomic force microscopes to study hydrodynamics around microand nanocylinders. These complementary methods allow the independent measurement of the added mass and friction terms over a large range of probe sizes, fluid viscosities, and solicitation conditions. A theoretical model based on an analytical description of the velocity field around the probe shows that the friction force depends on a unique parameter, the ratio of the probe radius to the thickness of the viscous boundary layer. We demonstrate that the whole range of experimental data can be gathered in a master curve, which is well reproduced by the model. This validates the use of these atomic force microscopy modes for a quantitative study of hydrodynamics and opens the way to the investigation of other sources of dissipation in simple and complex fluids down to the submicron scale.
We present a self-contained study of the dynamics of oscillating nanomenisci
anchored on nanometric topographical defects around a cylindrical nanofiber --
radius below 100 nm. Using frequency-modulation atomic force microscopy
(FM-AFM), we show that the friction coefficient surges as the contact angle is
decreased. We propose a theoretical model within the lubrification
approximation that reproduces the experimental data and provides a
comprehensive description of the dynamics of the nanomeniscus. The dissipation
pattern in the vicinity of the contact line and the anchoring properties are
discussed as a function of liquid and surface properties in addition to the
sollicitation conditions
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