Université PSL



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Wetting and spreading
Bonn D., Eggers J., Iindekeu J., Meunier J., Rolley E.
REVIEWS OF MODERN PHYSICS - 81(2) :739-805 - DOI:10.1103/RevModPhys.81.739 - 2009
Wetting phenomena are ubiquitous in nature and technology. A solid substrate exposed to the environment is almost invariably covered by a layer of fluid material. In this review, the surface forces that lead to wetting are considered, and the equilibrium surface coverage of a substrate in contact with a drop of liquid. Depending on the nature of the surface forces involved, different scenarios for wetting phase transitions are possible; recent progress allows us to relate the critical exponents directly to the nature of the surface forces which lead to the different wetting scenarios. Thermal fluctuation effects, which can be greatly enhanced for wetting of geometrically or chemically structured substrates, and are much stronger in colloidal suspensions, modify the adsorption singularities. Macroscopic descriptions and microscopic theories have been developed to understand and predict wetting behavior relevant to microfluidics and nanofluidics applications. Then the dynamics of wetting is examined. A drop, placed on a substrate which it wets, spreads out to form a film. Conversely, a nonwetted substrate previously covered by a film dewets upon an appropriate change of system parameters. The hydrodynamics of both wetting and dewetting is influenced by the presence of the three-phase contact line separating ``wet'' regions from those that are either dry or covered by a microscopic film only. Recent theoretical, experimental, and numerical progress in the description of moving contact line dynamics are reviewed, and its relation to the thermodynamics of wetting is explored. In addition, recent progress on rough surfaces is surveyed. The anchoring of contact lines and contact angle hysteresis are explored resulting from surface inhomogeneities. Further, new ways to mold wetting characteristics according to technological constraints are discussed, for example, the use of patterned surfaces, surfactants, or complex fluids.
Development of oligonucleotide microarray involving plasma polymerized acrylic acid” Thin Solid Films
R. Jafari , M. Tatoulian, D. Le Clerre, L. Talini, F. Richard, F. Arefi-Khonsari
Thin Solid Films - 517(19) :5763-8 - DOI:10.1016/j.tsf.2009.03.217 - 2009
This paper presents the manufacturing of biochips by using the COOH– derived polymer coating deposited by plasma polymerization of acrylic acid. This technology is based on depositing a thin layer obtained by plasma polymerization of acrylic acid which allows a further covalent immobilization of biomolecules on glass substrates. The plasma power value was optimized to maximize the stability of plasma polymerized acrylic acid (PPAA) coatings in water, which has a very important role for such applications. In order to obtain a covalent immobilization of DNA probes on the PPAA coated surface, the activation protocol of carboxylic function was carried out with the help of N-Hydroxy Succinimide and 1-Ethyl-3-(3-DimethylAminopropyl) Carbodiimide. The efficiency of PPAA coated in microarray applications was compared with two types of commercial slides. Such surfaces have shown very interesting results in terms of relative density of attached DNA probe molecules and signal-to-background ratio measured for target DNA hybridization. Nonspecific DNA bonding measurements showed only a small amount of nonspecific physisorption between the DNA probe and the PPAA-activated surfaces. This work shows that the plasma polymerization technique can be successfully applied to produce a high-quality glass surface for the manufacturing of DNA arrays.
In situ quantitative measurement of concentration profiles in a microreactor with submicron resolution using multiplex CARS microscopy
Dawn Schafer, Jeff A. Squier, Jan van Maarseveen, Daniel Bon, Mischa Bonn, Michiel Mu¨ller
JACS - 130(35) :11592-3 - DOI:10.1021/ja804158n - 2008
In situ quantitative imaging of concentration profiles of reactants and products inside a microfluidic reactor is achieved, with submicron spatial resolution with mM sensitivity and on ms time scales, for a given position. The label-free approach relies on quantitative vibrational spectroscopy, using Coherent Anti-Stokes Raman scattering microscopy in a spectrally resolved fashion, and is demonstrated on an elementary acid-base reaction.
Stable Modification of PDMS surface properties by plasma polymerization: Application to the formation of double emulsions in microfluidic systems
Vanessa Barbier, Michaël Tatoulian, Hong Li, Farzaneh Arefi-Khonsari ,Armand Ajdari and Patrick Tabeling
Langmuir - 22(12) :5230-2 - DOI:10.1021/la053289c - 2006
We describe a method based on plasma polymerization for the modification and control of the surface properties of poly(dimethylsiloxane) (PDMS) surfaces. By depositing plasma polymerized acrylic acid coatings on PDMS, we succeeded to fabricate stable (several days) hydrophilic and patterned hydrophobic/hydrophilic surfaces. We used this approach to generate direct and (for the first time in this material) double emulsions in PDMS microchannels.

14 publications.