Laboratoire d’analyse et d’architecture des systèmes
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
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.
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.
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
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.
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
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.
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
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.
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
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.
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.
J.CACHEUX, P.CORDELIER, T.LEICHLE
Affiche/Poster : Meeting of European Pancreatic Club ( EPC ) 2017 du 28 juin au 01 juillet 2017, Budapest (Hongrie), Juillet 2017 , N° 17537
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
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.
A.LECOMTE, A.LECESTRE, D.BOURRIER, MC.BLATCHE, L.JALABERT, E.DESCAMPS, C.BERGAUD
MEMS, TEAM, I2C
Revue Scientifique : Microelectronic Engineering, Vol.177, pp.70-73, Juin 2017 , N° 17182
We report on the plasma etching of thick (~23µm) Parylene C structures. Parylene C is a transparent polymer that benefits from high biocompatibility, flexibility and chemical inertness, and has gained increased attention over the years in the biomedical field. In the manufacturing process, highly defined structuration steps of Parylene C are essential, but techniques based on laser, scalpel and wet etching have shown to be unsuitable for properly cut structures. Plasma etching remains nowadays the most widespread option, though fast etching rate, lack of residues and high aspect ratios are still hard to achieve. To overcome these issues, the selection of both mask material and plasma conditions is crucial. Here, three masks-metal, positive and negative photoresists-are tested as stencils, and several plasma parameters are briefly studied in order to obtain the highest etching rate while maintaining good coverage. We showed that increasing the RF power up to a considerable 2800W while maintaining a moderate physical contribution (bias power, pressure, temperature), is optimal in the achievement of fast PaC etching without inducing thermal stress. Besides, the addition of a short fluorinated plasma in the midst of the process is shown to alleviate residues. For the first time, negative photoresist Intervia Bump Plating (BPN) coating followed by ICP 1-RIE 2 are used in order to pattern Parylene C-based structures, with a clean cut, vertical profile and fast etching rate (~0.87±0.06 µm/min) and a selectivity of 0.5. This solution was carried out to release unitary Parylene-based neural probes from a silicon wafer. Finally, cytotoxicity assays on these neural implants were performed to make sure that no trace of mask or stripper residues would jeopardize device biocompatibility.