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Laboratoire d’analyse et d’architecture des systèmes

Publications de l'équipe MEMS

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18283
01/08/2018

Direct laser fabrication of meso-scale 2D and 3D architectures with micrometric feature resolution

A.ACCARDO, R.COURSON, R.RIESCO ALVAREZ, V.RAIMBAULT, L.MALAQUIN

ELIA, TEAM, MEMS, MICA

Revue Scientifique : Additive Manufacturing, Vol.22, pp.440-446, Août 2018 , N° 18283

Lien : https://hal.laas.fr/hal-01875364

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Abstract

The realization of 2D and 3D meso-scale architectures is an area of research involving a wide range of disciplines ranging from materials science, microelectronics, phononics, microfluidics to biomedicine requiring millimeter to centimeter-sized objects embedding micrometric features. In the recent years, several technologies have been employed to provide optimal features in terms of object size flexibility, printing resolution, large materials library and fabrication speed. In this work, we report a fully customizable single-photon absorption 3D fabrication methodology based on direct laser fabrication. To validate this approach and highlight the versatility of the setup, we have fabricated a comprehensive ensemble of 2D and 3D designs with potential applications in biomimetics, 3D scaffolding and microfluidics. The high degree of tunability of the reported fabrication system allows tailoring the laser power, slicing and fabrication speed for each single area of the design. These unique features enable a rapid prototyping of millimeter to centimeter-sized objects involving 3D architectures with true freestanding subunits and micrometric feature reproducibility. The presented strategy fills indeed the current technological gap related to the development of meso-scale architectures required in multidisciplinary fields of research.

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18167
01/07/2018

Micromachining-Compatible, Facile Fabrication of Polymer Nanocomposite Spin Crossover Actuators

M.DMANRIQUE JUAREZ, F.MATHIEU, A.LABORDE, S.RAT, V.SHALABAEVA, P.DEMONT, O.THOMAS, L.SALMON, T.LEICHLE, L.NICU, G.MOLNAR, A.BOUSSEKSOU

MEMS, I2C, TEAM, LCC, CIRIMAT, LSIS, ENSAM, Lille

Revue Scientifique : Advanced Functional Materials, Vol.28, N°29, Juillet 2018, DOI 10.1002/adfm.201801970 , N° 18167

Lien : https://hal.laas.fr/hal-01816709

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[Fe II (Htrz) 2 (trz)](BF 4) spin crossover particles of 85 nm mean size were dispersed in an SU-8 polymer matrix and spray-coated onto silicon microcantilevers. The subsequent photo-thermal treatment of the polymer resist led to micrometer thick, smooth and homogeneous coatings, which exhibited well-reproducible actuation upon the thermally-induced spin transition. The actuation amplitude as a function of temperature was accurately determined by combining an integrated piezoresisitive detection with external optical interferometry, which allowed for the assessment of the associated actuation force (9.4 mN), stress (28 MPa), strain (1.0 %) and work density (140 mJ/cm 3) through a stratified beam model. The dynamical mechanical characterization of the films evidenced an increase of the resonance frequency and a concomitant decrease of the damping in the high temperature phase, which arise due to a combined effect of the thickness and mechanical property changes. The spray-coating approach was also successfully extended to scale up the actuators for the cm-range on a polymer substrate providing perspectives for biomimetic soft actuators.

143894
18168
05/06/2018

Self-Aligned Functionalization Approach to Order Neuronal Networks at the Single-Cell Level

A.CASANOVA, MC.BLATCHE, C.FERRE, H.MARTIN, D.GONZALES DUNIA, L.NICU, G.LARRIEU

MPN, I2C, INSERM, MEMS

Revue Scientifique : Langmuir, Vol.34, N°22, pp.6612-6620, Juin 2018 , N° 18168

Lien : https://hal.laas.fr/hal-01816434

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Abstract

Despite significant progress, our knowledge of the functioning of the central nervous system still remains scarce to date. A better understanding of its behavior, in either normal or diseased conditions, goes through an increased knowledge of basic mechanisms involved in neuronal function, including at the single-cell level. This has motivated significant efforts for the development of miniaturized sensing devices to monitor neuronal activity with high spatial and signal resolution. One of the main challenges remaining to be addressed in this domain is, however, the ability to create in vitro spatially ordered neuronal networks at low density with a precise control of the cell location to ensure proper monitoring of the activity of a defined set of neurons. Here, we present a novel self-aligned chemical functionalization method, based on a repellant surface with patterned attractive areas, which permits the elaboration of low-density neuronal network down to individual cells with a high control of the soma location and axonal growth. This approach is compatible with complementary metal-oxide–semiconductor line technology at a wafer scale and allows performing the cell culture on packaged chip outside microelectronics facilities. Rat cortical neurons were cultured on such patterned surfaces for over one month and displayed a very high degree of organization in large networks. Indeed, more than 90% of the network nodes were settled by a soma and 100% of the connecting lines were occupied by a neurite, with a very good selectivity (low parasitic cell connections). After optimization, networks composed of 75% of unicellular nodes were obtained, together with a control at the micron scale of the location of the somas. Finally, we demonstrated that the dendritic neuronal growth was guided by the surface functionalization, even when micrometer scale topologies were encountered and we succeeded to control the extension growth along one-dimensional-aligned nanostructures with sub-micrometrical scale precision. This novel approach now opens the way for precise monitoring of neuronal network activity at the single-cell level.

143896
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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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
17633
06/12/2017

Integration of FinFETs and 3D nanoprobes devices on a common bio-platform for monitoring electrical activity of single neurons

A.CASANOVA, MC.BLATCHE, F.MATHIEU, L.BETTAMIN, H.MARTIN, D.GONZALEZ-DUNIA, L.NICU, G.LARRIEU

MPN, I2C, INSERM, MEMS

Manifestation avec acte : International Electron Devices Meeting ( IEDM ) 2017 du 02 décembre au 06 décembre 2017, San Francisco (USA), Décembre 2017 , N° 17633

Lien : https://hal.laas.fr/hal-01816371

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Abstract

Our knowledge of the functioning of the central nervous system still remains scarce to date. A better understanding of its behavior, in either normal or diseased conditions, goes through an increased knowledge of basic mechanisms involved in neuronal function, including at the single cell resolution. In that scope, the miniaturization of electronic components and emergence of nano-biotechnology open new perspectives to follow neuronal activities at the single cell level. Here, we propose to co-integrate very high surface-to-volume ratio active (Fin-FETs) and passive devices (vertical nanowire-probes) on the same platform to monitor electrical activity of single mammalian neurons. Very high signal noise ratio has been demonstrated, especially in intracellular configuration (up to 80). The bio-platform was used to examine the effect of bio-chemical and electrical stimulations on neuronal activity.

143900
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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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
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