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17186
01/11/2017

In vitro and in vivo biostability assessment of chronically-implanted Parylene C neural sensors

A.LECOMTE, A.DEGACHE, E.DESCAMPS, L.DAHAN, C.BERGAUD

MEMS, IMS Bordeaux, CRCA

Revue Scientifique : Sensors and Actuators B: Chemical, Vol.251, pp.1001-1008, Novembre 2017 , N° 17186

Lien : https://hal.laas.fr/hal-01528604

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Abstract

Parylene C has rapidly gained attention as a exible biomaterial for a new generation of chronic neural probes. However, polymeric material failure in the form of delamination, swelling or tearing, often compromises device biostability in the long term. This work constitutes a rst step towards lifetime assessment of Parylene C implanted devices. We have conceived a Parylene C-based neural probe with PEDOT-nanostructured gold electrodes for the recording of brain activity. The material response to its biological environment was studied through in vitro soaking tests and in vivo wireless recordings in mice brain, both carried out for up to 6 months. Impedance monitoring and SEM images indicate that over the length of this trial, none of the implants presented with apparent signs of material degradation. Packaging reliability was a predominant factor in device failure, with a certain number of faulty connection appearing over time. This parameter aside, all soaked devices were stable in Articial Cerebro-Spinal Fluid, with impedances within 10% of their initial value after 6 months at 37°C. Besides, at least 70% of the implanted device were able to accurately record wirelessly high amplitude hippocampal Local Field Potentials from freely-moving mice, with steady Signal-to-Noise Ratio. In other terms, Parylene C implantable sensors responded minimally to articial and actual physiological conditions during a period of 6 months, which makes them promising candidates for reliable, chronically implanted sensors in the biomedical eld.

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17313
21/09/2017

Modification of the spontaneous seat-to-stand transition in cycling with bodyweight and cadence variations

B.WATIER, A.COSTES, N.TURPIN

GEPETTO, Toulouse III, CRIR

Rapport LAAS N°17313, doi 10.1016/j.jbiomech.2017.08.003, Septembre 2017

Lien : https://hal.laas.fr/hal-01584024

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Abstract

When a high power output is required in cycling, a spontaneous transition by the cyclist from a seated to a standing position generally occurs. In this study, by varying the cadence and cyclist bodyweight, we tested whether the transition is better explained by the greater power economy of a standing position or by the emergence of mechanical constraints that force cyclists to stand. Ten males participated in five experimental sessions corresponding to different bodyweights (80%, 100%, or 120%) and cadences (50 RPM, 70 RPM, or 90 RPM). In each session, we first determined the seat-to-stand transition power (SSTP) in an incremental test. The participants then cycled at 20%, 40%, 60%, 80%, 100%, or 120% of the SSTP in the seated and standing positions, for which we recorded the saddle forces and electromyogram (EMG) signals of eight lower limb muscles. We estimated the cycling cost using an EMG cost function (ECF) and the minimal saddle forces in the seated position as an indicator of the mechanical constraints. Our results show the SSTP to vary with respect to both cadence and bodyweight. The ECF was lower in the standing position above the SSTP value (i.e., at 120%) in all experimental sessions. The minimal saddle forces varied significantly with respect to both cadence and bodyweight. These results suggest that optimization of the muscular cost function, rather than mechanical constraints, explain the seat-to-stand transition in cycling.

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17159
19/09/2017

Integration of tunablr liquid crystal microcells on 1.55um photodetector arrays using nanoimprint technology

B.SADANI, B.BOISNARD, C.LEVALLOIS, C.PARANTHOEN, S.BOUCHOULE, L.DUPONT, T.CAMPS, J.B.DOUCET, V.BARDINAL

MICA, MILE, INSA Rennes, C2N, TEAM

Manifestation avec acte : International Conference on Micro and Nano Engineering ( MNE ) 2017 du 19 septembre au 22 septembre 2017, Braga (Portugal), Septembre 2017, 1p. , N° 17159

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Abstract

Associating the voltage-dependent birefringence of liquid crystals to III-V materials constitutes a promising way for the fabrication of widely tunable optical devices needed for future compact communications systems and optical sensors. In this work, liquid crystal microcells are efficiently integrated on 1.55μm photodiode arrays owing to the use of a nanoimprint setup for surface relief alignment grating fabrication and for liquid-crystal microcell sealing. Fabricated devices present a tuning range of 106nm for only 14V applied and without any current consumption.

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17288
12/09/2017

Effect of growth-induced X-ray exposure on the transport, magneto-transport and luminescence properties of blue-OLEDs

R.MONFLIER, L.SALVAGNAC, A.CHERIF, F.SEKLI, E.BEDEL-PEREIRA, I.SEGUY, J.F.BOBO

MPN, TEAM, MICA, CEMES/CNRS

Rapport LAAS N°17288, Septembre 2017, 20p.

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140776
17158
03/09/2017

Uniform fabrication of MOEMS arrays using dry thick resist films

T.CAMPS, S.ABADA, B.REIG, J.B.DOUCET, R.COURSON, L.SALVI, E.DARAN, V.BARDINAL

MICA, TEAM

Affiche/Poster : Eurosensors 2017 du 03 septembre au 06 septembre 2017, Paris (France), Septembre 2017, 2p. , N° 17158

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17238
01/09/2017

Evaluating depth distribution of excimer laser induced defects in silicon using micro-photoluminescence spectroscopy

R.MONFLIER, T.TABATA, M.TURPIN, A.BENYOUCEF, F.CRISTIANO, K.HUET, F.MAZZAMUTO, A.LA MAGNA, S.LOMBARDO, J.ROUL, E.BEDEL-PEREIRA

MPN, SCREEN-LASSE, CNR-IMM, Catania, I2C

Rapport LAAS N°17238, Septembre 2017, 1p.

Lien : https://hal.archives-ouvertes.fr/hal-01555348

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Abstract

Laser Thermal Annealing (LTA) has been demonstrated to be an effective method to create heavily doped regions required for ultra-shallow junctions, in which dopants are typically introduced by ion implantation. More generally, laser annealing is very attractive due to the localised nature of the annealing process (both on the wafer surface and in depth), allowing dopants to be activated while preserving the integrity of the surrounding areas. Similarly, it is generally accepted that the laser induced damage, if any, is also localised and is reduced when using ultrashort pulses. However, the depth distribution of the laser induced damage has been rarely investigated in detail, with few works reporting on the subsurface doping and damage in laser-doped Si solar cells [1, 2].

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17208
30/08/2017

Notice technique : Spectrométrie des électrons Auger

Q.GRAVELIER, A.ARNOULT, G.LACOSTE, F.MESNILGRENTE, L.ASTIE

TEAM, MICA

Rapport LAAS N°17208, Août 2017, 10p.

Lien : https://hal.archives-ouvertes.fr/hal-01542695

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Résumé

La spectroscopie des électrons Auger (AES : « Auger electron spectroscopy ») induite par les électrons, est une technique d’analyse des surfaces qui permet l’identification des éléments à la surface des solides (à l’exception de H et He) qui constituent les toutes premières couches atomiques (quelques nanomètres). Son principe repose sur le principe de l’effet Auger, en l’analysant les énergies cinétiques, caractéristiques des éléments dont ils sont issus, des électrons en surface. C’est énergies sont induites par un faisceau d’électrons d’incidences normal, focalisé sur la surface du substrat, de quelques kiloélectronvolts, dans une enceinte sous ultravide, équipé d’un analyseur d’électrons. Cette notice technique a pour but de présenter le spectromètre du LAAS-CNRS aux personnes souhaitant l’utiliser et sert d’appuis au personnel formateur. Un exemplaire de ce formulaire restera à disposition des utilisateurs à proximité de l’équipement.

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17193
19/07/2017

Multi-photon direct laser writing and 3D imaging of polymeric freestanding architectures for cell colonization

A.ACCARDO, MC.BLATCHE, R.COURSON, I.LOUBINOUX, C.THIBAULT, L.MALAQUIN, C.VIEU

ELIA, I2C, TEAM, INSERM

Revue Scientifique : Small, Vol.13, N°27, 1700621p., Juillet 2017 , N° 17193

Lien : https://hal.archives-ouvertes.fr/hal-01534024

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Abstract

The realization of 3D architectures for the study of cell growth, proliferation and differentiation is a task of fundamental importance for both technological and biological communities involved in the development of biomimetic cell culture environments. Here we report the combination of 3D freestanding scaffolds realized by multi-photon direct laser writing (DLW), seeded with neuroblastoma cells, and their multi-technique characterization using advanced 3D fluorescence imaging techniques. The high accuracy of the fabrication process (≈ 200 nm) provides a much finer control of the meso-, micro-and nano-scale features compared to other 3D printing technologies based on fused deposition modeling, inkjet printing, selective laser sintering or polyjet technology. Scanning electron microscopy (SEM) provided detailed insights about the morphology of both cells and cellular Complete Manuscript interconnections around the 3D architecture. On the other hand, the nature of the seeding in the inner core of the 3D scaffold, inaccessible by conventional SEM imaging, was unveiled by light sheet fluorescence microscopy and multi-photon confocal imaging which highlighted an optimal cell colonization both around and within the 3D scaffold as well as the formation of long neuritic extensions. The results open appealing scenarios for the use of the developed 3D fabrication/3D imaging protocols in several neuroscientific contexts.

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17140
13/07/2017

Nanoscale boundary conditions and wetting scrutinized at picometer dynamical forcing

J.P.AIME, J.P.SALVETAT, M.FAUCHER, T.ONDARCUHU, D.THERON, B.LEGRAND

IECB, CRPP, Pessac, IEMN Villeneuve, CEMES/CNRS, MEMS

Rapport LAAS N°17140, Juillet 2017, 15p.

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17157
01/07/2017

Nanoscale investigations on interchain organization in thin films of polymer-liquid crystal blend

C.VILLENEUVE-FAURE, D.LE BORGNE, V.VENTALON, I.SEGUY, K.MOINEAU CHANE CHING, E.BEDEL-PEREIRA

LAPLACE, LCC, MICA, MPN

Revue Scientifique : The Journal of Chemical Physics, Vol.147, N°1, 014701p., Juillet 2017, doi http://dx.doi.org/10.1063/1.4991415 , N° 17157

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Abstract

Optimized nanomorphology in organic thin active layers is crucial for good performance in organic solar cells. However, the relation between morphology and electronic properties at nanoscale remains not completely understood. Here, we study the effect of film thickness and temperature annealing on the ordering of poly(3-hexylthiophene) chains when the polymer is blended with a columnar liquid crystalline molecule. Electronic absorption, atomic force microscopy measurements, and Raman spectroscopy show that morphology and chain ordering of the blend depend on the film thickness. We highlight the benefit of using a liquid crystal in organic blends, opening the way to use simple processing methods for the fabrication of organic electronic devices.

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