Nano-physique des fluides aux interfaces
Présentation
Notre activité de recherche est centrée sur l’étude des propriétés hydrodynamiques à l’échelle nanométrique des fluides confinés en utilisant un microscope de force atomique.
Cette thématique se trouve à la pointe des recherches actuelles en nano-fluidique où les problèmes de confinements et les interactions fluides-interfaces sont importantes.
Plusieurs facteurs influencent la Rhéologie d’un fluide proche d’une paroi, comme la rugosité de l’interface, la nature chimique de la surface et la présence des impuretés.
Les membres de la thématique NAFI
La thématique est composée de:
- Abdelhamid MAALI, DR
- Rodolphe BOISGARD, MdC
- Zaicheng ZHANG, Post-Doc
- Muhammad ARSHAD, PhD
- Hao Zhang, PhD
Thèmes de recherches
- Structuration en monocouche et viscosité d’un liquide nano-confiné.
- Hydrodynamique à l’échelle nanométrique : glissement de l’eau sur des surfaces solides.
- Réponse rhéologique de solutions de polymères dans un écoulement confinée.
- Réponse viscoélastique des interfaces liquide-air et liquide-solid mou.
- Etude de l’écoulement de l’air nano-confiné : Glissement, Transpiration thermique et Force de Knudsen.
- Frottement entre microparticules à l’échelle nanometriques.
Results:
- The contactless measurement of viscoelastic properties of soft PDMS layer using dynamic atomic force microscope
We have performed the contactless measurement of the viscoelastic property of polymer thin films in wide range of frequencies. The experiment was done in a liquid environment using dynamic Atomic Force Microscope (AFM) method. The nanoscale flow induced by the oscillation of the colloidal probe provides a precise hydrodynamic force acting on the soft thin film. From the measured mechanical response, we obtain the storage and loss moduli of the thin film. The experimental results are in good agreement with theoretical prediction for all the working frequencies. The result paves the way for the frequency response study of viscoelastic properties of the soft surfaces, like, nanobubbles, live cells and tissues.
- An experimental study on the role of friction in non-Brownian suspensions rheology:
We have performed a quantitative experimental validation of Lobry’s [1] model linking viscosity to friction and, in particular, shear thinning to load dependent friction coefficient. For this purpose, we have measured by using an AFM the pairwise friction coefficient of polystyrene particles, immersed in a Newtonian liquid, for different normal loads [2] . The friction coefficient obtained is then introduced into the viscosity model proposed by Lobry et al. The viscosity of suspensions consisting of these same particles dispersed in the liquid used for AFM measurements is then measured for several particle volume fractions. The very good agreement between the measured viscosity values and those predicted by the model with the coefficient of friction measured by AFM as input data [2], shows unambiguously the relevance of the scenario proposed by Lobry model [1].
[1] L. Lobry, E. Lemaire, F. Blanc, S. Gallier and F. Peters, Journal of Fluid Mechanics, ,860, 682, 2019.
[2] M. Arshad, A. Maali, C. Claudet, L. Lobry, F. Peters, and E. Lemaire, submitted.
We performed a non-contact atomic-force microscopy measurements of the hydrodynamic interactions between a rigid sphere and an air bubble in water at the micro-scale. The size of the bubble is found to have a significant effect on the response due to the long-range capillary deformation of the airliquid interface. To rationalize the experimental data, we develop a viscocapillary lubrication model accounting for the finite-size effect. The comparison between experiments and theory allows us to measure the air-liquid surface tension, without contact, paving the way towards robust non-contact tensiometry of polluted air-liquid interfaces.
We have performed the measurements of resonant thermal capillary oscillations of a hemispherical liquid gas interface obtained using a half bubble deposited on a solid substrate. The thermal motion of the hemispherical interface is investigated using an atomic force microscope cantilever that probes the amplitude of vibrations of this interface versus frequency. The spectrum of such nanoscale thermal oscillations of the bubble surface presents several resonance peaks and reveals that the contact line of the hemispherical bubble is pinned on the substrate. The analysis of these peaks allows to measure the surface viscosity of the bubble interface. Minute amounts of impurities are responsible for altering the rheology of the pure water surface.
We have performed 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 force increases as the gap is reduced and shows a saturation at small gap. The results are in excellent agreement with scaling arguments and a 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, an empirical scaling law for the observed saturation of the lift force is given and discussed.
The “free” water surface is generally prone to contamination with surface impurities be they surfactants, particles or other surface active agents. The presence of such impurities can modify flow boundary near such interfaces in a drastic manner. Here we show that vibrating a small sphere mounted on an AFM cantilever near a gas bubble immersed in water, is an excellent probe of surface contamination. Both viscous and elastic forces are exerted by an air-water interface on the vibrating sphere even when very low doses of contaminants are present. The viscous drag forces show a cross-over from no-slip to slip boundary conditions while the elastic forces show a nontrivial variation as the vibration frequency changes. We provide a simple model to rationalize these results and propose a simple way of evaluating the concentration of such surface impurities.
Thermal noise measurements of a vibrating sphere close to micro-sized air bubbles in water with an atomic force microscope. The sphere was glued at the end of a cantilever with a resonance frequency of few kHz. The sub-Angstrom thermal motion of the micro-sphere reveals an elasto-hydrodynamic coupling between the sphere and the air-bubble. The results are in perfect agreement with a model incorporating macroscopic capillarity and fluid flow on the bubble surface with full slip boundary conditions.
Recent Publications
- Z. Zhang, Y. Wang, Y. Amarouchene, R. Boisgard, H. Kellay, A. Würger and A. Maali
Near-field probe of thermal capillary fluctuations of a hemispherical bubble
arXiv:2009.03637.
- V. Bertin*, Z. Zhang*, R. Boisgard, C. Grauby-Heywang, E. Raphaël, T. Salez, and A. Maali
Non-contact rheology of finite-size air-water interfaces
- Z. Zhang, V. Bertin, M. Arshad, E. Raphael, T. Salez and A. Maali
Direct measurement of the elastohydrodynamic lift force at the nanoscale
Phys. Rev. Lett. 124, 054502
Doi.
- Abdelhamid Maali, Rodolphe Boisgard, Hamza Chraibi, Zaicheng Zhang, Hamid Kellay, et al..
Visco-elastic drag forces and crossover from no-slip to slip boundary conditions for flow near air-water interfaces.
Physical Review Letters, American Physical Society, 2017, 118 (8), pp.084501.
Doi. Hal - Yuliang Wang, Binglin Zeng, Hadush Tedros Alem, Zaicheng Zhang, Elisabeth Charlaix, Abdelhamid Maali.
Visco-capillary response of gas bubbles probed by thermal noise atomic force measurement.
Langmuir, American Chemical Society, 2017, in press
Doi. Hal - Abdelhamid Maali, Stéphane Colin, Bharat Bhushan.
Slip length measurement of gas flow.
Nanotechnology, Institute of Physics, 2016, 27 (37), pp.374004 (1-12).
Doi. Hal - Abdelhamid Maali, Rodolphe Boisgard.
Precise damping and stiffness extraction in acoustic driven cantilever in liquid.
Journal of Applied Physics, American Institute of Physics, 2013, 114 (14), pp.144302 (1-5).
Doi. Hal - Ahmad Darwiche, François Ingremeau, Yacine Amarouchene, Abdelhamid Maali, Isabelle Dufour, et al.
Rheology of polymer solutions using colloidal-probe atomic force microscopy.
Physical Review E : Statistical, Nonlinear, and Soft Matter Physics, American Physical Society, 2013, 87 (6), 062601 (10p.).
Doi. Hal - Abdelhamid Maali, Bharat Bhushan.
Nanobubbles and their role in slip and drag.
Journal of Physics: Condensed Matter, IOP Publishing, 2013, 25 (18), pp.184003 (1-12).
Doi. Hal - Yunlu Pan, Bharat Bhushan, Abdelhamid Maali.
Slip Length Measurement of Confined Air Flow on Three Smooth Surfaces.
Langmuir, American Chemical Society, 2013, 29 (13), pp.4298-4302.
Doi. Hal - Abdelhamid Maali, Y. Pan, Bharat Bhushan, E. Charlaix.
Hydrodynamic drag-force measurement and slip length on microstructured surfaces.
Physical Review E : Statistical, Nonlinear, and Soft Matter Physics, American Physical Society, 2012, 85 (6), pp.066310.
Doi. Hal - Isabelle Dufour, Abdelhamid Maali, Yacine Amarouchene, Cédric Ayela, Benjamin Caillard, et al..
The Microcantilever: a Versatile Tool for Measuring the Rheological Properties of Complex Fluids.
Journal of sensors, 2012, 2012, 719898 (9 p.).
Doi. Hal - Abdelhamid Maali, Bharat Bhushan.
Measurement of Slip Length on Superhydrophobic Surfaces.
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, Royal Society, The, 2012, 370 (1967), pp.2304-2320.
Doi. Hal - Anastase Hakizimana, Abdelhamid Maali, Touria Cohen-Bouhacina.
Structuration et nanorhéologie d’un liquide confiné: étude par AFM dynamique..
Rwanda Journal, 2011, 20 (1), pp.51-66.
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