Retour au site du LAAS-CNRS

Laboratoire d’analyse et d’architecture des systèmes
Choisir la langue : FR | EN

104documents trouvés

18144
01/08/2018

Hybrid vesicles from lipids and block copolymers: phase behavior from the micro-to the nano-scale

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

Lien : https://hal.laas.fr/hal-01810239

Diffusable

Plus d'informations

Abstract

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.

143773
18179
23/05/2018

Simple Synthetic Molecular Hydrogels from Self- Assembling Alkylgalactonamides as Scaffold for 3D Neuronal Cell Growth

A.CHALARD, L.VAYSSE, P.JOSEPH, L.MALAQUIN, S.ASSIE-SOULEILLE, B.LONETTI, J.C.SOL, I.LOUBINOUX, J.FITREMANN

MILE, INSERM, ELIA, I2C, IMRCP

Revue Scientifique : ACS applied materials & interfaces, Vol.10, N°20, pp.17004-17017, Mai 2018 , N° 18179

Lien : https://hal.laas.fr/hal-01810656

Diffusable

Plus d'informations

Abstract

In this work, we demonstrated that the hydrogel obtained from a very simple and single synthetic molecule, N-heptyl-galactonamide was a suitable scaffold for the growth of neuronal cells in 3D. We evidenced by confocal microscopy the presence of the cells into the gel up to a depth of around 200 µm, demonstrating that the latter was permissive to cell growth and enabled a true 3D colonization and organization. It also supported successfully the differentiation of adult human neuronal stem cells (hNSCs) into both glial and neuronal cells and the development of a really dense neurofilament network. So the gel appears to be a good candidate for neural tissue regeneration. In contrast with other molecular gels described for cell culture, the molecule can be obtained at the gram scale by a one-step reaction. The resulting gel is very soft, a quality in accordance with the aim of growing neuronal cells, that requires low modulus substrates similar to the brain. But because of its fragility, specific procedures had to be implemented for its preparation and for cell labeling and confocal microscopy observations. Notably, the implementation of a controlled slow cooling of the gel solution was needed to get a very soft but nevertheless cohesive gel. In these conditions, very wide straight and long micrometric fibers were formed, held together by a second network of flexible narrower nanometric fibers. The two kinds of fibers guided the neurite and glial cell growth in a different way. We also underlined the importance of a tiny difference in the molecular structure on the gel performances: parent molecules, differing by a one-carbon increment in the alkyl chain length, N-hexyl-galactonamide and N-octyl-galactonamide, were not as good as N-heptyl-galactonamide. Their differences were analysed in terms of gel fibers morphology, mechanical properties, solubility, chain parity and cell growth.

143937
18147
03/05/2018

Insight into the Bonding of Silanols to Oxidized Aluminum Surfaces

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

Lien : https://hal.laas.fr/hal-01810862

Diffusable

Plus d'informations

Abstract

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.

143814
18148
27/04/2018

Transport of nano-objects in narrow channels: influence of Brownian diffusion, confinement and particle nature

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

Lien : https://hal.laas.fr/hal-01810125

Diffusable

Plus d'informations

Abstract

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.

143816
17094
01/04/2018

Design and evaluation of a smart insole: application for continuous monitoring of frail people at home

Y.CHARLON, E.CAMPO, D.BRULIN

S4M

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

Diffusable

Plus d'informations

Abstract

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.

141595
18217
22/03/2018

Design and simulation of 10 GHz VCO based on RF MEMS solenoid inductor

N.HABBACHI, H.BOUSSETTA, M.A.KALLALA, A.BOUKABACHE, P.PONS, K.BESBES

Monastir, MILE, MINC

Manifestation avec acte : International Multi-Conference on Systems, Signals and Devices ( SSD ) 2018 du 19 mars au 22 mars 2018, Hammamet (Tunisie), Mars 2018, 5p. , N° 18217

Lien : https://hal.laas.fr/hal-01838589

Diffusable

Plus d'informations

Abstract

This paper reports the design and simulation of 10 GHz VCO based on RF MEMS solenoid inductor. We have investigated four RF MEMS solenoid inductors using FEM software. Indeed, we have studied the effect of different dielectric substrate and metallic coil on inductors responses. Higher performances are obtained using copper coil and SU8 dielectric substrate: SRF= 20.8 GHz, Qmax= 60.9, and L = 2.6 nH at 10 GHz. Therefore, we have designed and investigated a cross-coupled CMOS VCO based on the best RF MEMS solenoid inductor. The obtained results show a wide tuning range TR = 46% comprised between 10 GHz and 14.6 GHz, and a good linearity of frequency variation in response of control voltage. Moreover, output signals present a high voltage upper than 1.2 V and a low phase-noise PN =-102.37 dBc/Hz at 1 MHz. In addition, the spectral analyze show that output peak power reaches 14.56 dBm at a center frequency of 10 GHz and the second harmonic is less than-58.9 dBm. These results prove high spectral signal ability of the proposed RF MEMS CMOS VCO at 10 GHz.

144224
18216
22/03/2018

Modeling of microfluidically tuned capacitor for RF applications

N.HABBACHI, H.BOUSSETTA, M.A.KALLALA, A.BOUKABACHE, P.PONS, K.BESBES

Monastir, MILE, MINC

Manifestation avec acte : International Multi-Conference on Systems, Signals and Devices ( SSD ) 2018 du 19 mars au 22 mars 2018, Hammamet (Tunisie), Mars 2018, 5p. , N° 18216

Lien : https://hal.laas.fr/hal-01838593

Diffusable

Plus d'informations

Abstract

This paper presents the modeling of microfluidically tuned capacitor for RF applications. The designed structure is based on performances variations following DI water displacement between capacitor's electrodes. We have modeled the electric field and the current distribution using FEM tool for different DI water position in microchannels. The obtained results at 4.5 GHz show an important variation of electric field and current distribution that impacts the capacitor performances: the capacitance value is comprised between Cmin = 0.11 pF and Cmax = 5.76 pF, the factor value decreases from Qmax = 84.27 to Qmin = 3.99, and the resonant frequency ranges from 5.67 GHz to 19.8 GHz. Indeed, the capacitance variation reaches Tr = 5136% and the broadband ability is higher than 240%.

144222
18096
01/03/2018

Spatial Analysis of Nanofluidic-Embedded Biosensors for Wash-Free Single-Nucleotide Difference Discrimination

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

Lien : https://hal.laas.fr/hal-01762631

Diffusable

Plus d'informations

Abstract

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.

143275
18069
25/02/2018

Evaporation with the formation of chains of liquid bridges

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

Lien : https://hal.laas.fr/hal-01701199

Diffusable

Plus d'informations

Abstract

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.

142845
18017
08/02/2018

Simulation of Single Particle Displacement Damage in Silicon – Part III: First Principles Characterization of Defect Properties

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

Lien : https://hal.archives-ouvertes.fr/hal-01685608

Diffusable

Plus d'informations

Abstract

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.

142335
Les informations recueillies font l’objet d’un traitement informatique destiné à des statistiques d'utilisation du formulaire de recherche dans la base de données des publications scientifiques. Les destinataires des données sont : le service de documentation du LAAS.Conformément à la loi « informatique et libertés » du 6 janvier 1978 modifiée en 2004, vous bénéficiez d’un droit d’accès et de rectification aux informations qui vous concernent, que vous pouvez exercer en vous adressant à
Pour recevoir une copie des documents, contacter doc@laas.fr en mentionnant le n° de rapport LAAS et votre adresse postale. Signalez tout problème de dysfonctionnement à sysadmin@laas.fr. http://www.laas.fr/pulman/pulman-isens/web/app.php/