Laboratoire d’analyse et d’architecture des systèmes
C.MAGNANI, C.MONTIS, G.MANGIAPIA, A.F.MINGOTAUD, C.MINGOTAUD, C.ROUX, P.JOSEPH, D.BERTI, B.LONETTI
IMRCP, UNIFI, Forschungszentrum, MILE
Revue Scientifique : Colloids and Surfaces B: Biointerfaces, Vol.168, pp.18-28, Août 2018 , N° 18144
In recent years, there has been a growing interest in the formation of copolymers-lipids hybrid self-assemblies, which allow combining and improving the main features of pure lipids-based and copolymer-based systems known for their potential applications in the biomedical field. In this contribution we investigate the self-assembly behavior of dipalmitoylphosphatidylcholine (DPPC) mixed with poly(butadiene-b-ethyleneoxide) (PBD-PEO), both at the micro- and at the nano-length scale. Epifluorescence microscopy and Laser Scanning Confocal microscopy are employed to characterize the morphology of micron-sized hybrid vesicles. The presence of fluid-like inhomogeneities in their membrane has been evidenced in all the investigated range of compositions. Furthermore, a microfluidic set-up characterizes the mechanical properties of the prepared assemblies by measuring their deformation upon flow: hybrids with low lipid content behave like pure polymer vesicles, whereas objects mainly composed of lipids show more variability from one vesicle to the other. Finally, the structure of the nanosized assemblies is characterized through a combination of Dynamic Light Scattering, Small Angle Neutron Scattering and Transmission Electron Microscopy. A vesicles-to-wormlike transition has been evidenced due to the intimate mixing of DPPC and PBD-PEO at the nanoscale. Combining experimental results at the micron and at the nanoscale improves the fundamental understanding on the phase behavior of copolymer-lipid hybrid assemblies, which is a necessary prerequisite to tailor efficient copolymer-lipid hybrid devices.
M.POBERZNIK, D.COSTA, A.HEMERYCK, A.KOKALJ
Ljubljana, IRCP, M3, Institut Jožef Stefan
Revue Scientifique : Journal of Physical Chemistry C, Vol.122, N°17, pp.9417-9431, Mai 2018 , N° 18147
In the context of elucidating the mechanism by which siloxane-based sol–gel coatings adhere to the surface, the adsorption of a model silanol molecule, CH3Si(OH)3, and its oligomers (up to the trimer) on oxidized and fully hydroxylated aluminum substrates is described using density functional theory (DFT). To link our calculations with the synthesis of siloxane-based sol–gel coatings, the focus is given on the condensation mechanism. We find that the formation of a monodentate bonding mode with the hydroxylated surface via the condensation mechanism is exothermic by ≥0.5 eV in all considered cases. In contrast, the formation of a bidentate bonding mode is exothermic only for the trimer. However, taking entropic contributions into account, we find that the formation of the bidentate bonding mode is exergonic already for the dimer due to favorable entropic effects of a liberated water molecule during the reaction. In contrast, the reaction entropy is unfavorable for the monodentate formation because the effects of the immobilized silanol molecule counteract and surpass those of the liberated water molecule. The monodentate to bidentate transformation is therefore determined by the interplay between entropy and energy, and we find that the longer the oligomer chain, the more likely is the bidentate formation due to increasingly favorable reaction energies. These results further reveal that for the silanol monomer, additional molecule–surface chemical bonds do not form via the condensation mechanism due to the strained configuration it has to adopt in the bidentate bonding mode.
O.LIOT, M.SOCOL, L.GARCIA, J.THIERY, A.FIGAROL, A.F.MINGOTAUD, P.JOSEPH
MILE, IPBS, IMRCP
Revue Scientifique : Journal of Physics: Condensed Matter, Vol.30, N°23, 23400p., Avril 2018 , N° 18148
This paper presents experimental results about transport of dilute suspensions of nano-objects in silicon-glass micrometric and sub-icrometric channels. Two kinds of objects are used: solid, rigid latex beads and spherical capsule-shaped, soft polymersomes. They are tracked using fluorescence microscopy. Three parameters are studied: confinement (ratio between particle diameter and channel depth), Brownian diffusion and particle nature. The aim of this work is to understand how these different parameters affect the transport of suspensions in narrow channels and to understand the different mechanisms at play. Concerning the solid beads we observe the appearance of two regimes, one where the experimental mean velocity is close to the expected one and another where this velocity is lower. This is directly related to a competition between confinement, Brownian diffusion and advection. These two regimes are shown to be linked to the homogeneity of particles distribution in the channel depth, which we experimentally deduce from velocity distributions. This inhomogeneity appears during the entrance process into the sub-micrometric channels, as for hydrodynamic separation or deterministic lateral displacement. Concerning the nature of the particles we observed a shift of transition towards the second regime likely due to the relationships between shear stress and polymersomes mechanical properties which could reduce the inhomogeneity imposed by the geometry of our device.
Y.CHARLON, E.CAMPO, D.BRULIN
Revue Scientifique : Expert Systems with Applications, Vol.95, pp.57-71, Avril 2018, DOI https://doi.org/10.1016/j.eswa.2017.11.024 , N° 17094
The objectives of this work are to develop a technological solution designed to support active aging of frail older individuals and to conduct a first evaluation of the devices. We wish to bring a reflection in the field of connected health by setting up a remote medical follow-up. In this context, the connected object presented in this article aims at implementation a longitudinal follow-up of the walk by a health professional. Continuous remote data analysis applies behavior learning methods by modeling walking habits and allows the detection of deviations by application of thresholds defined by the expert. We propose an instrumented shoe insole to provide such monitoring (number of steps, distance covered and gait speed). In this perspective, we designed a low power microelectronic device integrated into the thickness of an insole in order to demonstrate the technical feasibility of such a device in laboratory and in living conditions. The project called “FOOT-TEST” is funded by the DIRECCTE of the Midi-Pyrenees Region in France. This project brought together a manufacturer who specializes in the design of foot-care systems, geriatricians and our laboratory specialized in electronics to propose a technical solution adapted to frail individuals. Two smart insole prototypes have been produced and a first evaluation of the smart insole in real use conditions has been performed. According to user feedback, the smart insole seems to be much easier to use than commercial connected pedometers. Moreover, in terms of performance, the smart insole provides better results. In this paper, we present specifications of the device, technological choices and the design of two versions of the smart insole, methods used to measure desired settings, a first evaluation of the system and, finally, preliminary conclusions and work in progress.
J.CACHEUX, M.BRUT, A.BANCAUD, P.CORDELIER, T.LEICHLE
MEMS, M3, MILE, CRCT-INSERM
Revue Scientifique : ACS Sensors, Vol.3, N°3, pp.606-611, Mars 2018 , N° 18096
In this work, we demonstrate that the analysis of spatially resolved nanofluidic-embedded biosensors permits the fast and direct discrimination of single-nucleotide difference (SND) within oligonucleotide sequences in a single step interaction. We design a sensor with a linear dimension much larger than the channel depth in order to ensure that the reaction over the whole sensor is limited by the convection rate. Thus, the targets are fully collected, inducing a nonuniform spatial hybridization profile. We also use the nanoscale height of the channel, which enables us to minimize the amount of labeled molecules flowing over the sensor and hence to reduce the fluorescence background, to carry out real-time hybridization detection by fluorescence microscopy. Taken together, these design rules allow us to show that the spatial hybridization profile depends on the duplex affinity, and we speculate that the on and off-rate constants can be inferred during target injection, which is not possible in local analysis where the dissociation step through rinsing must be conducted. We finally manage to discriminate a GT mismatch on a microRNA sequence by optimizing the interaction temperature and the probe design after a few minutes of interaction in a single step protocol. This work may be applied to any biosensing transduction scheme with spatial resolution, e.g., surface plasmon resonance imaging, integrated into nanofluidic channels for applications where high oligonucleotide sequence selectivity and short analysis times are required.
C.CHEN, P.JOSEPH, S.GEOFFROY, M.PRAT, P.DURU
IMFT, MILE, LMDC
Revue Scientifique : Journal of Fluid Mechanics, Vol.837, pp.703-728, Février 2018 , N° 18069
The objective of the present work is to study the drying of a quasi-2D model porous medium, thereafter called micromodel, initially filled with a pure liquid. The micromodel consists of cylinders measuring 50 µm in both height and diameter, radially arranged as a set of neighbouring spirals and sandwiched between two horizontal, flat plates. As drying proceeds, air invades the pore space and elongated liquid films trapped by capillary forces form along the spirals. These films consist of " chains " of liquid bridges connecting neighbouring cylinders. They provide an hydraulic connectivity between the central, bulk liquid cluster and the external rim of the cylinders pattern, where evaporation is taking place during a first constant evaporation-rate drying stage. The first goal of the present paper is to describe experimentally the phase distribution during drying, notably the liquid films evolution, which controls the evaporation kinetics (e.g. the depinning of the films from the external rim signs the end of the constant evaporation rate period). Then, a visco-capillary model for the drying process is presented. It is based on numerical simulations of a liquid film capillary shape and of the viscous flow within a film. The model shows a reasonably good agreement with the experimental data. Thus, the present study is a step towards direct modelling of the films effect on the drying of more complex porous media (e.g. packing of beads) and should be of interest for multiphase flow applications in porous media, involving transport within liquid films.
A.JAY, A.HEMERYCK, N.RICHARD, L.MARTIN SAMOS, M.RAINE, A.LE ROCH, N.MOUSSEAU, V.GOIFFON, P.PAILLET, P.PAILLET, M.GAILLARDIN, P.MAGNAN
ISAE, M3, CEA-DAM, UNG, UdeM
Revue Scientifique : IEEE Transactions on Nuclear Science, 8p., Février 2018, DOI 10.1109/TNS.2018.2790843 , N° 18017
A first principles study of the defects generated by displacement cascades in silicon is performed. This work is particularly focused on two defect configurations; the di-vacancy and the tri-interstitial, both identified in previous Molecular Dynamics (MD) and kinetic Activation Relaxation Technique (k-ART) simulations [1, 2]. By combining structural, energy and migration properties evaluated within the framework of the standard Density Functional Theory (DFT) and electronic properties calculated within the G 0 W 0 approximation, a reconstruction of the corresponding thermally-activated electrical signal generated by each defect is obtained. Their contribution to Dark Current (DC) and Dark Current Random Telegraph Signal (DC-RTS) measured in image sensors is then discussed.
B.CHAMI, M.SOCOL, R.MALBEC, A.BANCAUD
Affiche/Poster : MICROFLUIDICS2017 - Ecole thématique ( ) 2017 du 25 juin au 30 juin 2017, Carcans Maubuisson (France), Février 2018, 1p. , N° 17515
H.RANCHON, J.CACHEUX, B.REIG, O.LIOT, P.TEERAPANICH, T.LEICHLE, P.JOSEPH, A.BANCAUD
MILE, MEMS, TEAM
Revue Scientifique : Langmuir, Vol.34, N°4, pp.1394-1399, Janvier 2018 , N° 18012
We investigate the pressure-driven transport of particles 200 or 300 nm in diameter in shallow microfluidic channels ∼1 μm in height with a bottom wall characterized by a high roughness amplitude of ∼100 nm. This study starts with the description of an assay to generate cracks in hydrophilic thin polymer films together with a structural characterization of these corrugations. Microfluidic chips of variable height are then assembled on top of these rough surfaces, and the transport of particles is assessed by measuring the velocity distribution function for a set of pressure drops. We specifically detect anomalous transport properties for rough surfaces. The maximum particle velocity at the centerline of the channel is comparable to that obtained with smooth surfaces, but the average particle velocity increases nonlinearly with the flow rate. We suggest that the change in the boundary condition at the rough wall is not sufficient to account for our data and that the occurrence of contacts between the particle and the surface transports the particle away from the wall and speeds up its motion. We finally draw perspectives for the separation by field-flow fractionation.
B.SARPI, R.ZIRMI, M.PUTERO, M.BOUSLAMA, A.HEMERYCK, S.VIZZINI
IM2NP, LATAGE, LSM, M3
Revue Scientifique : Applied Surface Science, Vol.423, N°Part B, pp.522-527, Janvier 2018 , N° 17312
Using Auger Electron Spectroscopy (AES), Scanning Tunneling Microscopy/Spectroscopy (STM/STS) and Low Energy Electron Diffraction (LEED), we report an in-situ study of amorphous magnesium silicide (Mg2Si) ultra-thin films grown by thermally enhanced solid-phase reaction of few Mg monolayers deposited at room temperature (RT) on a Si(100) surface. Silicidation of magnesium films can be achieved in the nanometric thickness range with high chemical purity and a high thermal stability after annealing at 150 °C, before reaching a regime of magnesium desorption for temperatures higher than 350 °C. The thermally enhanced reaction of one Mg monolayer (ML) results in the appearance of Mg2Si nanometric crystallites leaving the silicon surface partially uncovered. For thicker Mg deposition nevertheless, continuous 2D silicide films are formed with a volcano shape surface topography characteristic up to 4 Mg MLs. Due to high reactivity between magnesium and oxygen species, the thermal oxidation process in which a thin Mg2Si film is fully decomposed (0.75 eV band gap) into a magnesium oxide layer (6–8 eV band gap) is also reported.