Mois : avril 2016

The subject of the Ph.D. thesis is in the domains of (electro)microfluidics and (bio)nanotechnology. The project will work towards developing methods for extracting information on the chemical and biological state of microfluidic samples (e.g. the presence of biomarkers) by analyzing the behaviour of individual metallic nanoparticles injected into the sample. These particles are characterised by their stochastic microscopic movements, their optical signal and their response to the microscale electric field.

More information : SATIE-ENS-Rennes-thesis-offer-2016

While the pervaporation process leading to dense materials is well understood [4, 5], several issues remain unsolved: they concern the mechanical instabilities that often occur during the solidification. In most of the investigated cases (dispersions, polymers, inks, …), the evaporation of the solvent indeed significantly deforms the pervaporation matrix, leading to the delamination of the material from the substrate and very often, fracture and crack eventually form. Such an outcome is quite deleterious to the good quality of the final material, both for its characterization and its application.
We wish to understand (and to master) the combined roles of i) the microfluidic matrix and ii) the dispersed fluid undergoing evaporation on the properties of the final printed micro-structures.
Importantly, the high confinement of the pervaporation technique is likely to play a crucial role as compared to the traditional case of the drying of thin films, but the two techniques share important similarities which we will exploit next in the film-making processes in order to produce large-scale materials.

More informations : 2015_AMADEus_047

They often require a preliminary step of separation in order to isolate microbial cells, presumed pathogens, from the other particle components and/or to concentrate them before identification. The samples often contain a mixture of suspended particles and several micro-organisms species with different morphologies and sizes. An easy and portable way to achieve preliminary sorting or separation of these micro-organisms can be done based on their migration under flow in micro-channels.

More information : Post-doc-migration-complex-shape-particles-FERMaT

A geometry of particular interest concerns flows in a Hele-Shaw cell, i.e. a channel whose depth is much smaller than its width and length. This classical problem has been studied in depth, both theoretically and experimentally. While the theoretical solutions predict that the relative velocity of an inviscid bubble should be twice the velocity of the outer fluid, this is never observed in practice. Instead, bubbles travel at lower speeds than the outer fluid. Moreover, complex recirculation patterns are observed for bubbles rising in a quiescent outer fluid [5]. All of these observations point out the effect of an uneven surfactant coverage of the interface and its redistribution due to the fluid motion.

More informations : PostdoctoralPositionLIONS

Dans le domaine des sciences des matériaux, les microréacteurs sont utilisés principalement pour la séparation et l’extraction sélective des ions métalliques ou pour la synthèse de nanomatériaux. L’équipe Colloïdes Inorganiques au sein du laboratoire PHENIX a démontré l’efficacité des procédés microfluidiques et des microréacteurs dans la synthèse de nanomatériaux à base d’oxydes de fer simples ou multifonctionnels.

Plus d’informations : offre de thèse _AAH