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Publications de l'équipe MEMS

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47documents trouvés

18117
01/06/2018

A review on mechanical considerations for chronically-implanted neural probes

C.BERGAUD, A.LECOMTE, E.DESCAMPS

MEMS, MICA

Revue Scientifique : Journal of Neural Engineering, Vol.15, N°3, Juin 2018 , N° 18117

Lien : https://hal.laas.fr/hal-01764292

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Abstract

This review intends to present a comprehensive analysis of the mechanical considerations for chronically-implanted neural probes. Failure of neural electrical recordings or stimulation over time has shown to arise from foreign body reaction and device material stability. It seems that devices that match most closely with the mechanical properties of the brain would be more likely to reduce the mechanical stress at the probe/tissue interface, thus improving body acceptance. The use of low Young's modulus polymers instead of hard substrates is one way to enhance this mechanical mimetism, though compliance can be achieved through a variety of means. The reduction of probe width and thickness in comparison to a designated length, the use of soft hydrogel coatings and the release in device tethering to the skull, can also improve device compliance. Paradoxically, the more compliant the device, the more likely it will fail during the insertion process in the brain. Strategies have multiplied this past decade to offer partial or temporary stiffness to the device to overcome this buckling effect. A detailed description of the probe insertion mechanisms is provided to analyze potential sources of implantation failure and the need for a mechanically-enhancing structure. This leads us to present an overview of the strategies that have been put in place over the last ten years to overcome buckling issues. Particularly, great emphasis is put on bioresorbable polymers and their assessment for neural applications. Finally, a discussion is provided on some of the key features for the design of mechanically-reliable, polymer-based next generation of chronic neuroprosthetic devices.

143461
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

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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
18070
01/02/2018

Measuring Interfacial Polymerization Kinetics Using Microfluidic Interferometry

A.NOWBAHAR, V.MANSARD, J.MECCA, T.ARROWOOD, T.SQUIRES

Univ. of California, MEMS, The Dow Chemical

Revue Scientifique : Journal of the American Chemical Society, Vol.140, N°9, pp.3173-3176, Février 2018 , N° 18070

Lien : https://hal.archives-ouvertes.fr/hal-01734561

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Abstract

Interfacial polymerization is used in a range of elds, both academic and industrial, for the production of bers, capsules , and lms. Despite its widespread use, measuring the reaction kinetics of interfacial polymerization has remained a challenge. For example, reaction kinetics for polyamide reverse osmosis membranes are dicult to obtain and rarely reported due to the thinness of lms, and rapidity of their formation at the liquid-liquid interface. Here, polyamide lm formation is studied using a microuidic, interferometry-based technique to measure monomer concentration near the interface as the reaction occurs. Our results are consistent with a polymeriza-tion reaction that is initially controlled by a reaction-diusion boundary layer within the organic phase. Using simple scaling arguments to analyze our data, we report the rst measurements of the reaction rate constant for this system.

142873
18012
30/01/2018

Accelerated transport of particles in confined channels with high roughness amplitude

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

Lien : https://hal.archives-ouvertes.fr/hal-01682628

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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.

142202
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.

140318
17595
26/10/2017

Rapid discrimination of single-nucleotide differences through the spatial analysis of a nanofluidic-embedded biosensor

J.CACHEUX, M.BRUT, A.BANCAUD, P.CORDELIER, T.LEICHLE

MEMS, M3, MILE, CRCT-INSERM

Manifestation avec acte : International Conference on Miniaturized Systems for Chemistry and Life Sciences ( MicroTas ) 2017 du 22 octobre au 26 octobre 2017, Savannah (USA), Octobre 2017, 2p. , N° 17595

Lien : https://hal.laas.fr/hal-01699274

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Abstract

We demonstrate that the spatial analysis of nanofluidic-embedded biosensors permits the fast and direct discrimination of single-nucleotide difference (SND) within microRNA sequences in a single step interaction. We first show that the spatial hybridization profile depends on the duplex affinity, and we speculate that the affinity constant 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.

142847
16584
24/10/2017

Probing electrical activity of single neurons based on 1D nanostructures: from extra to intracellular interfacing.

A.CASANOVA, MC.BLATCHE, F.MATHIEU, A.LECESTRE, C.FERRE, D.GONZALES DUNIA, L.NICU, G.LARRIEU

MPN, I2C, TEAM, INSERM, EXT, MEMS

Manifestation avec acte : IEEE Nanotechnology Materials and Devices Conference ( IEEE NMDC ) 2016 du 09 octobre au 12 octobre 2016, Toulouse (France), Octobre 2017, 2p. , N° 16584

Lien : https://hal.laas.fr/hal-01462968

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The struggle against neurodegenerative diseases is one of the major challenges in the near future and the global understanding of these diseases goes through a better expertise at the single cell level of basic mechanisms involved in neuronal networks. We need to investigate closer to the cellular material and in this way, miniaturization of electronic components and emergence of nano-biotechnology open new perspectives. Indeed, we are now able to fabricate high sensitive nano-devices to follow neuronal activities. Here, we will present two different approaches to interface neurons, a first one based on a nano-FET for extracellular recordings and a second one using vertical nanowire arrays (nano-electrodes) for intracellular measurements.

141337
17439
01/10/2017

Structural and mechanical characterization of hybrid metallic-inorganic nanosprings

N. S.HABTOUN, S.HOUMADI, B.REIG, E.POUGET, D.DEDOVET, M.H.DELVILLE, R.ODA, F.CRISTIANO, C.BERGAUD

MEMS, TEAM, CBMN, ICMCB-CNRS, MPN

Revue Scientifique : Materials Research Express, Vol.4, N°10, 105023p., Octobre 2017 , N° 17439

Lien : https://hal.archives-ouvertes.fr/hal-01651965

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Silica nanosprings (NS) are fabricated by a sol–gel deposition of silica precursors onto a template made of self-assembled organic chiral nanostructures. They are deposited and assembled on microstructured silicon substrates, and then metallized and clamped in a single lithography-free step using a focused ion beam (FIB). The resulting suspended hybrid metallic/inorganic NS are then characterized with high-resolution transmission electron microscopy (HRTEM) and scanning TEM/energy-dispersive X-ray spectroscopy (STEM/EDX), showing the atomic structure of the metallic layer. Three-point bending tests are also carried out using an atomic force microscope (AFM) and supported by finite element method (FEM) simulation with COMSOL Multiphysics allowing the characterization of the mechanical behavior and the estimation of the stiffness of the resulting NS. The information obtained on the structural and mechanical properties of the NS is discussed for future nano-electro-mechanical system (NEMS) applications.

141703
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.

Diffusion restreinte

140098
17501
01/07/2017

A bistable microelectromechanical system actuated by spin-crossover molecules

M.DMANRIQUE JUAREZ, F.MATHIEU, V.SHALABAEVA, J.CACHEUX, S.RAT, L.NICU, T.LEICHLE, L.SALMON, G.MOLNAR, A.BOUSSEKSOU

MEMS, I2C, LCC

Revue Scientifique : Angewandte Chemie International Edition, Vol.56, N°28, pp.8074-8078, Juillet 2017 , N° 17501

Lien : https://hal.archives-ouvertes.fr/hal-01687804

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We report on a bistable MEMS device actuated by spin-crossover molecules. The device consists of a freestanding silicon microcantilever with an integrated piezoresistive detection system, which was coated with a 140 nm thick film of the [Fe(HB(tz)3)2] (tz=1,2,4-triazol-1-yl) molecular spin-crossover complex. Switching from the low-spin to the high-spin state of the ferrous ions at 338 K led to a reversible upward bending of the cantilever in agreement with the change in the lattice parameters of the complex. The strong mechanical coupling was also evidenced by the decrease of approximately 66 Hz in the resonance frequency in the high-spin state as well as by the drop in the quality factor around the spin transition.

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