Les thermoplastiques contenant du PDMS ont attiré beaucoup d’attention à cause de leur potentiel dans un large spectre d’applications. Lors du mélange du PDMS avec des thermoplastiques, le problème de la compatibilité ne peut être ignoré. Cette dernière engendre de faibles propriétés mécaniques ainsi qu’une surface rugueuse. Par conséquent, le défi principal des mélanges PDMS/thermoplastique est de trouver un moyen efficace et adapté, comme le mélange réactif in situ, pour compatibiliser les différentes phases. Récemment, nous avons trouvé une réaction intéressante entre l’hydrosilane (SiH) et les groupes carbonyles catalysés par le triruthénium dodecacarbonyle [Ru3(CO)12]. Il a le potentiel pour réaliser cette compatibilisation réactive. Dans un premier temps, nous avons étudié le mécanisme de la réaction d’hydrosilylation catalysée par le ruthénium dans le cas du N-méthylpropionamide. Les composés N-silicatés formés qui peuvent jouer par la suite le rôle de compatibilisant lors du mélange réactif. Dans un deuxième temps, cette réaction d’hydrosilylation a été étendue au mélange réactif de PA12 avec du PDMS terminé hydride en conditions de mélange fondu. La réaction a été réalisée rapidement (en 1 minute) en présence de Ru3 (CO) 12 (1wt%). Ensuite, nous avons étudié la microstructure des deux mélanges. En comparaison avec le mélange non réactif, la dispersion du PDMS dans celui réactif était clairement améliorée puisque la taille des domaines. En outre, dans de telles conditions réactives et en présence du catalyste de ruthénium, une réaction d’oxydation du PDMS-SiH est partiellement observée. Ceci inclue par exemple les propriétés de stabilité thermique, de comportement cristallin, d’énergie de surface et de perméabilité et séparation des gaz. Dans un troisième temps, nous nous sommes intéressés à l’application de la réaction d’hydrosilylation catalysée par le ruthénium aux composites PBT/polyméthylhydrosiloxane (PMHS). Cependant, à cause des températures élevées nécessaires à la mise en forme du PBT (220°C), une réaction de réticulation entre le PBT et le PMHS apparait mais également et une auto-réticulation du PMHS. Enfin, ces résultats montrent une application potentielle et initial de ruthénium hydrosilylation catalysées à compatibilisation réactive entre l'hydropolysiloxane et un polyamide ou un polyester / Polydimethylsiloxane (PDMS) containing thermoplastics have attracted much attention due to their potential in wide range of applications. However, when blending PDMS with thermoplastics, the incompatible problem cannot be ignored. It may results in weak mechanical properties and a rough surface. Therefore, the main challenge of PDMS and thermoplastic blend is to find an efficient and convenient way like in situ reactive blending to realize the compatibilization between tthem. Recently, we found an interesting reaction between hydrosilane (SiH) and carbonyl group catalyzed by triruthenium dodecacarbonyl [Ru3(CO)12]. It has potential to realize such reactive compatibilization. Firstly, we investigated the mechanism of ruthenium catalyzed hydrosilylation reaction of N-methylpropionamide, and found that the formed N-silylated compounds which can work as compatibilizers in later reactive blending. Then this hydrosilylation reaction was extended to the reactive blending of PA12 with hydride terminated PDMS under molten processing conditions. The reaction was carried out quickly (in 1 minute) in the presence of Ru3(CO)12 (1wt%). Compared to the unreacted one, the dispersion of PDMS after reaction was obviously improved. Besides, in such reactive conditions, PDMS-SiH oxidation reaction was partially observed. This phenomenon leads to a second PDMS gel based phase. Properties like thermal stability, crystalline behavior, surface energy and gas permeability and separation of such blends were also studied. Secondly, ruthenium catalyzed hydrosilylation was also applied to PBT and polymethylhydrosiloxane (PMHS) which was processed at higher temperature (220°C). The final material includes the crosslinking network formed between PBT and PMHS and a part of PMHS self-crosslinking forming PMHS gel-like phase due to the higher processing temperature of PBT and high reactivity of PMHS. Finally, these results show a potential and initial application of ruthenium catalyzed hydrosilylation to reactive compatibilization between hydride polysiloxane and polyamide or polyester

Dans l’optique de développement de matériaux performants avec une approche respectueuse de l’environnement, l’obtention de copolymères à blocs de type hard-soft avec une forte proportion de polydiméthylsiloxane (PDMS) en utilisant le procédé d’extrusion est une étape vers des élastomères thermoplastiques d’intérêt. Afin de s’affranchir de la faible réactivité des extrémités de chaînes des longues macromolécules, la voie originale mise en avant consiste en la réalisation de copolymères ayant une partie centrale PDMS courte puis en l’allongement de celle-ci selon les propriétés visées. L’étape critique d’allongement est effectuée à l’aide de bases phosphazènes comme agents de polymérisation de décaméthylcyclopentasiloxane (D5). Dans un premier temps, une approche chemio-rhéologique de la polymérisation du D5 à l’aide de ces superbases a été réalisée. L’acquisition des données intrinsèques de cette réaction permet de mettre au point la modélisation de l’évolution de viscosité du système en cours de réaction, vérifiant ainsi sa compatibilité avec l’utilisation de l’extrusion réactive. Dans un second temps, l’utilisation d’une architecture modèle de PDMS fonctionnalisé en bout de chaîne par des groupements chimiques volumineux de type naphtyl valide l’hypothèse d’allongement du chaînon central par insertion de D5 selon cette catalyse. Finalement, cette approche a été appliquée à des architectures macromoléculaires de type poly(styrène-b-diméthylsiloxane-b-styrène). Dans ce cas, les résultats sont, à cette heure, moins probants. Ceci est potentiellement dû à l’aspect procédé de nos manipulations. Cette dernière observation révèle l’intérêt de l’extrusion dans ce type de synthèse. / Nowadays the development of performing new materials using an environmental friendly route is a challenge. To produce hard-soft block copolymers based on a high polydimethylsiloxane (PDMS) content using reactive extrusion process is a milestone to reach thermoplastic elastomers. Because of the low reactivity of high molecular weight macromolecule chain ends an original route is described. It consists in the synthesis of copolymers containing low central PDMS and then increasing the molecular weight of this central part. This crucial step is performed using phosphazene bases as polymerization agents of decamethylcyclopentasiloxane (D5). Firstly, the polymerization of D5 by phosphazene bases has been investigated by chemiorheological means. To define intrinsic data of this reaction allows modelling the viscosity change during the chemical reaction. Thus, it is observed this polymerization system is compatible with reactive extrusion. Secondly, we investigate the hypothesis of increasing the molecular weight of a short central PDMS part in a triblock copolymer by D5 insertion using the catalysis system previously described. Naphtyl end-chain functionalized PDMS was used as a model. So we confirmed this route as an interesting one to achieve the targeted macromolecular architectures. Finally, we tried to produce poly(styrene-b-dimethylsiloxane-b-styrene) through this way. In this case, early investigations are not so convincing. This may come from the experimental device used. This last observation stresses out the great potential of extrusion process to implement such a route to reach thermoplastic elastomers based on high polysiloxane content.

Ces travaux de thèse concernent l’étude de matériaux supramoléculaires en vue de générer de nouveaux élastomères silicones auto-cicatrisants. Dans un premier temps, l’étude de la bibliographie a permis de recenser les différentes voies intégrant de la chimie supramoléculaire développées dans le domaine des silicones et basées sur les liaisons hydrogène. L’effet des groupements associatifs sur les propriétés rhéologiques et mécaniques des matériaux a été discuté, et les limitations de ces systèmes soulignées. La chimie développée par l’équipe du Dr. Leibler, adaptée par la suite aux silicones par le Pr. Zhang et son équipe, a particulièrement été analysée lors de notre étude de compréhension. Les relations structures/propriétés n’étaient pas clairement élucidées à l’issue de cette étude de la bibliographie. Des études modèles impliquant un PDMS téléchélique aminé ainsi que de l’urée ont donc été réalisées. La caractérisation précise des structures des produits de réaction a permis de mettre en exergue certaines corrélations entre structures (choix du groupement associant, masse molaire du copolymère, fonctionnalité) et propriétés (rhéologiques et mécaniques) qui n’avaient alors pas été démontrées pour ces systèmes. Il a aussi été montré que la force des groupements et les enchevêtrements jouent un rôle primordial. Une chimie différente, inspirée des travaux de Yilgör et al sur les copolymères segmentés, a par la suite été envisagée, en mettant en jeu cette fois la réaction d’aza-Michael. Cette synthèse se démarque du premier système par un meilleur contrôle de la structure macromoléculaire finale. Un silicone supramoléculaire élastomère et auto-cicatrisant a été obtenu en combinant une fonctionnalité importante et une masse molaire finale élevée. Les propriétés mécaniques de ce polymère ont été optimisées par l’ajout de charges plus ou moins renforçantes. L’impact d’un tel renfort sur les propriétés auto-cicatrisantes du système a été discuté. / This PhD thesis focused on the investigation of supramolecular materials in order to generate new self-healing supramolecular silicone elastomers. Firstly, a literature review on silicone materials was realized and we identified the different ways developed in the silicone domain that imply supramolecular chemistry and in particular hydrogen-bonds. The influence of associating groups on rheological and mechanical properties of these materials was discussed, and the restrictions of such systems were highlighted. The chemistry developed by Dr. Leibler and co-workers, later adapted to silicones by Pr Zhang and his team, was deeply investigated during our comprehension study. Relationships between structure and properties were nonetheless not fully elucidated in these studies. Model reactions involving telechelic amino-PDMS and urea were then carried out. The thorough characterization of the final structure of the reaction products highlighted few correlations between structural parameters (choice of the type of associating group, molecular weight of copolymer, functionality) and properties (rheological and mechanical) that had not been demonstrated yet for these systems. We showed that, among others, the strength of the associating groups as well as the entanglements play a fundamental role. A different chemistry, inspired by Yilgör and co-workers’ studies on segmented copolymers, was later considered by carrying out an aza-Michael reaction. This synthesis differs from the previous one by its better control of the final macromolecular structure. A supramolecular silicone elastomer with self-healing abilities was obtained by combining a large functionality together with a high final molecular weight. Mechanical properties of this material were further enhanced through the addition of more or less reinforcing fillers. The influence of such reinforcement on self-healing capacity of this system was discussed.

[pt] Um espectrômetro de massa PDMS-252Cf-TOF (Time-of-Flight Plasma Dessorption Mass Spectrometry) foi usado para analisar amostras condensadas de água pura e misturas de H2O:C2H2, H2O:C2H6 e H2O:N2O, em temperaturas entre 10 e 100 K. Os íons dessorvidos devido ao impacto foram identificados e seus rendimentos de dessorção determinados. Observa-se que a distribuição desses rendimentos em função da massa dos íons pode ser descrita pela soma de duas exponenciais. Este resultado sugere fortemente que ocorrem dois processos de formação de agregados: um, via emissão direta de fragmentos do sólido e outro, via recombinação de fragmentos na fase gasosa. Para H2O puro, os principais agregados dessorvidos são: ((H2O)nH2O+, (H2O)nH3O+, On +, (H2O)nO−, (H2O)nOH− e On −. Para misturas de gelos H2O:C2H2 e H2O:C2H6, são observadas as séries (C2H2)n + e (C2H6)n +. Para H2O:N2O, as séries Nn +, (O)nN2 +, (O)nN2−, (O)nN4−, e (N2)nNO+ são as mais abundantes. A Teoria do Funcional da Densidade (DFT), no nível B3LYP/6-31G, foi usada para calcular a estabilidade molecular dos íons moleculares secundários emitidos. Cálculos para as estruturas C2Hm + (com m = 1 a 6) geraram 26 estruturas estáveis. As curvas de estabilidade por massa/carga obtidas são comparadas com aquelas obtidas experimentalmente para os rendimentos de dessorção por massa/carga para os mesmos íons. Tal metodologia é utilizada para prever as conformações mais prováveis dos íons dessorvidos. / [en] A PDMS-252Cf-TOF (Time-of-Flight Plasma Desorption Mass Spectrometry) mass spectrometer was used to analyze condensed samples of pure water and mixtures of H2O:C2H2, H2O:C2H6 and H2O:N2O, at temperatures between 10 and 100 K. The ions desorbed due to the projectile impact were identified and their desorption yields determined. It is observed that the yield distributions as a function of the mass of the ions can be described by the sum of two exponentials. This result strongly suggests that two processes of aggregate formation occur: one, via direct emission of fragments from the solid and the other, via recombination of fragments in the gas phase. For pure H2O, the main desorbed aggregates are: ((H2O)nH2O+, (H2O)nH3O+, On +, (H2O)nO−, (H2O)nOH− and On −. For mixtures of ices H2O:C2H2 and H2O:C2H6, the series (C2H2)n + and (C2H6)n + are observed. For H2O:N2O, the series Nn +, (O)nN2 +, (O)nN2−, (O)nN4−, and (N2)nNO+ are the most abundant. Density Functional Theory (DFT), at the B3LYP/6-31G level, was used to calculate the molecular stability of emitted secondary molecular ions. Calculations for the C2Hm + structures (with m = 1 to 6) generated 26 stable structures. The stability curves per mass/charge obtained are compared with those obtained experimentally for the desorption yields per mass/charge for the same ions. Such methodology is used to predict the most likely conformations of the desorbed ions.

Ce travail de thèse présente la conception et la réalisation d'un dispositif microfluidique en PDMS (Polydiméthylsiloxane) pour exploration des diagrammes de phase. Le microsystème est basé sur le principe de pervaporation (évaporation à travers une membrane) et comporte des microchambres indépendantes de 5nL de solution dont on fait varier la concentration au court du temps. Il est possible de concentrer jusqu'à l'observation de transitions de phases (démixtion, nucléation, cristallisation, ...). Nous avons montré que la pervaporation est une piste intéressante pour l'exploration de diagrammes de phases. En parallèle, nous avons développé un outil original de mesure in situ en temps réel de la concentration, paramètre essentiel du criblage. Cet outil, basé sur le principe de réfractométrie, a pour avantage d'être non intrusif et ne requiert aucune modification particulière du microsystème. La méthode consiste à utiliser les parois des microcanaux comme éléments optiques. Nous montrons que cette méthode permet de mesurer un coefficient de diffusion et un rapport de viscosité dans une jonction en T sans ajout de traceurs ni utilisation de la fluorescence. Nous avons utilisé cette méthode de mesure de la concentration lors d'expériences sur des systèmes modèles (solutions ioniques, surfactants, polymères, protéines, ...).

In this thesis I present a microfluidic platform developed to control dissolved gases and monitor dissolved oxygen concentrations within the microenvironment of isolated small blood vessels. Dissolved gas concentrations are controlled via permeation through the device substrate material using a 3D network of gas and liquid channels. Dissolved oxygen concentrations are measured on-chip via fluorescence quenching of an oxygen sensitive probe embedded in the device. Dissolved oxygen control was validated using the on-chip sensors as well as a 3D computational model. The platform was used in a series of preliminary experiments using olfactory resistance arteries from the mouse cerebral vascular bed. The presented platform provides the unique opportunity to control dissolved oxygen concentrations at high temporal resolutions (<1 min) and monitor dissolved oxygen concentrations in the microenvironment surrounding isolated blood vessels.

Diseases involving fibrosis cause tens of thousands of deaths per year in the US alone. These diseases are characterized by a large amount of extracellular matrix, causing stiff abnormal tissues that may not function correctly. To take steps towards curing these diseases, a fundamental understanding of how cells interact with their substrate and how mechanical forces alter signaling pathways is vital. Studying the mechanobiology of cells and the interaction between a cell and its extracellular matrix can help explain the mechanisms behind stem cell differentiation, cell migration, and metastasis. Due to the correlation between force, extracellular matrix assembly, and substrate stiffness, it is vital to make in vitro models that more accurately simulate biological stiffness as well as measure the amount of force and extracellular matrix assembly. To accomplish this, blends of two types of poly(dimethylsiloxane) (PDMS) were made and the material properties of these polymer blends were characterized. A field of 5µm or 7µm microscopic pillars (referred to as posts) with a diameter of 2.2µm were fabricated from these blends. Each combination of PDMS blend and post height were calibrated and the stiffness was recorded. Additionally, polymer attachment experiments were run to ensure cells survived and had a normal phenotype on the different blends of PDMS when compared to pure PDMS. Finally, cells were placed onto a field of posts and their forces were calculated using the new stiffness found for each blend of post. Varying the PDMS material stiffness using blends allow posts to be much more physiologically relevant and help to create more accurate in vitro models while still allowing easy and accurate force measurement. More biologically relevant in vitro models can help us acquire more accurate results when testing new drugs or examining new signaling pathways.

Neste trabalho uretanas livres de isocianatos produzidas a partir de um precursor bis(ciclocarbonato) oligomérico contendo segmentos de poli(dimetil siloxano) (CCPDMS) foram sintetizadas. Para tal, utilizou-se diferentes aminas primárias como a 3-aminometil-3,5,5 trimetilciclohexilamina (IPDA) e as monoaminas 3-aminopropil(trietóxisilano) (APTES), feniletilamina (PEA), catecol amina (dopamina) e um decapeptídeo derivado da proteína de adesão de mariscos (mefp-1).O precursor oligomérico CCPDMS foi produzido por fixação de dióxido de carbono em anéis epóxi catalisado por um sal quarternário de amônio, o brometo de tetraetilamônio (BTA). O precursor CCPDMS foi então reagido com as aminas por meio de polimerização por abertura de anel formando hidroxiuretanas derivadas de PDMS (PDMSUr) com diferentes terminações de cadeia. Tendo como terminador de cadeia o APTES, foi possível produzir um material híbrido com domínios inorgânicos de sílica organicamente modificada (ormosil) interligadas com a parte orgânica de PDMS por meio de ligações uretana. Nesta matriz híbrida foram adicionadas diferentes porcentagens mássicas de ácido fosfotúngstico (PWA), variando entre 1% a 55%. Os materiais foram caracterizados quanto à sua estrutura química por técnicas espectroscópicas (Ressonância Magnética Nuclear, Infravermelho, Espectroscopia de Fotoelétrons, MALDI-ToF), propriedade anti-corrosão (espectroscopia de impedância eletroquímica, polarização potenciodinâmica), propriedades superficiais (energia livre superficial, nanoindentação), análise morfológica (Microscopia Eletrônica de Varredura), estabilidade térmica (Análise Termogravimétrica), testes de adesão (pull-off-test e cisalhamento), testes microbiológicos (adesão de bactérias, tecidos e citotoxicidade), além de ensaios de fotocromismo. O polioxometalato PWA conferiu propriedades fotocrômicas aos filmes híbridos de PDMSUr com máxima absorbância de 1,6 u.a após irradiação por luz ultra-violeta (UV). PDMSUr híbridas com ou sem PWA foram testadas como adesivos para vidro, alumínio, aço (SS316L) e liga de titânio (Ti6Al4V) apresentando valores de força de adesão entre 2-7 MPa. Filmes de PDMSUr preparados em diferentes substratos apresentaram comportamento bacteriostático frente à adesão de Escherichia coli (E.coli) e Lactobacillus casei (L.casei). A PDMSUr biomimética terminada por grupos catecóis foi capaz de formar camadas em superfícies metálicas apresentando boa estabilidade frente à remoção da camada depositada por lavagem com etanol. / Free isocyanate urethanes produced from an oligomeric precursor bis(cyclic carbonate) bearing poly(dimethylsiloxane) (CCPDMS) were synthesized in this work. Different primary amines such as 3-Aminomethyl-3,5,5-trimethylcyclohexylamine (IPDA) and monoamines 3-aminopropyltriethoxysilane (APTES), phenylethylamine (PEA), catechol amine (dopamine) and a decapeptide derived from marine mussel foot protein (mefp-1). The precursor cyclic carbonate CCPDMS was obtained from carbon dioxide fixation into epoxy rings catalized by a quaternary ammonium salt, tetraethylamonium bromide (TEAB). The precursor CCPDMS was reacted with the different amines by ring opening polymerization affording the formation of hydroxyurethanes PDMS derived (PDMSUr) with different chain terminations. Using APTES as chain terminator was feasible to obtain a hybrid material containing inorganic domains of organically modified silica (ormosil) interconnected to the organic part PDMS through urethane bond. In this hybrid matrix different mass percentages, varying from 1%wt to 55 wt%, of phosphotungstic acid (PWA) were added. The materials were characterized regarding their chemical structure by spectroscopic techniques (Nuclear Magnetic Resonance, Infrared, and X-ray photoelectron spectroscopy), mass spectrometry (MALDI-ToF and GPC), anti corrosive property (Electrochemical Impedance Spectroscopy and potentiodynamic polarization), surface properties (free surface energy, nanoindentation), morphology (Scanning Electron Microscopy), thermal stability (Thermogravimetric analysis), adhesion strenght measurements (pull-off-test and lap-shear), microbiologic assays (bacteria adhesion, tissue adhesion and citotoxicity test) besides photochromic assays. The polyoxometalate PWA provided photochromic property to the PDMSUr hybrid films presenting a maximum absorbance of 1.6 a.u after ultraviolet (UV) irradiation. Hybrids PDMSUr with or without PWA were tested as adhesive for glass, aluminium, steel (SS316L) and titanium alloy (Ti6Al4V) showing adhesion strength values ranging from 2-7 MPa. PDMSUr films prepared on different substrates showed bacteriostatic behavior against Escherichia coli (E.coli) and Lactobacillus casei (L.casei). The biomimetic PDMSUr catechol endcapped was able to form a layer on metallic surfaces showing good stability after rinsing with ethanol.

My research broadly covers various important aspects of microfluidic devices and biosensors. Specifically, this dissertation reports: (1) a new and effective room temperature method of bonding polydimethylsiloxane (PDMS) microfluidics to substrates such as silicon and glass, (2) a new microfluidic pump concept and implementation specifically designed to repeatedly drive a small sample volume (<1 µL) very rapidly (~500 µL/min) through a sensor-containing flow channel to significantly decrease sensor response time through advection-driven rather than diffusion-driven mass transport, (3) use of a new microfluidic material based on polyethylene glycol diacrylate (PEGDA) to implement impedance-based dynamic nanochannel sensors for protein sensing, and (4) an investigation of galvanoluminescence and how to avoid it for conditions important to fluorescence-based dielectrophoresis (DEP) microfluidic biosensors. Over the last decade, the Nordin research group has developed a lab-on-a-chip (LOC) biosensor based on silicon photonic microcantilever arrays integrated with polydimethylsiloxane (PDMS) microfluidics for protein biomarker detection. Integration requires reliable bonding at room temperature with adequate bond strength between the PDMS element and microcantilever sensor substrate. The requirement for a room temperature process is particularly critical because microcantilevers must be individually functionalized with antibody-based receptor molecules prior to bonding and cannot withstand significant heating after functionalization. I developed a new room temperature bonding method using PDMS curing agent as an intermediate adhesive layer. Two curing agents (Sylgard 184 and 182) were compared, as well as an alternate UV curable adhesive (NOA 75). The bond strength of Sylgard 184 was found to be stronger than Sylgard 182 under the same curing conditions. Overnight room temperature curing with Sylgard 184 yields an average burst pressure of 433 kPa, which is more than adequate for many PDMS sensor devices. In contrast, UV curable epoxy required a 12 hour bake at 50 °C to achieve maximum bond strength, which resulted in a burst pressure of only 124 kPa. In many biosensing scenarios it is desirable to use a small sample volume (<1 µL) to detect small analyte concentrations in as short a time as possible. I report a new microfluidic pump to address this need, which we call a reflow pump. It is designed to rapidly pump a small sample volume back and forth in a flow channel. Ultimately, the flow channel would contain functionalized sensor surfaces. The rapid flow permits use of advection-driven mass transport to the sensor surfaces to dramatically reduce sensor response times compared to diffusion-based mass transport. Normally such rapid flow would have the effect of decreasing the fraction of analyte molecules in the volume that would see the sensor surfaces. By configuring the pump to reflow fluid back and forth in the flow channel, the analyte molecules in the small sample volume are used efficiently in that they have many opportunities to make it to the sensor surfaces. I describe a 3-layer PDMS reflow pump that pumps 300 nL of fluid at 500 µL/min for 15 psi actuation pressure, and demonstrate a new two-layer configuration that significantly simplifies pump fabrication. Impedance-based nanochannel sensors operate on the basis of capturing target molecules in nanochannels such that impedance through the nanochannels is increased. While simple in concept, the response time can be quite long (8~12 hours) because the achievable flow rate through a nanochannel is very limited. An approach to dramatically increase the flow rate is to form nanochannels only during impedance measurements, and otherwise have an array of nanotrenches on the surface of a conventional microfluidic flow channel where they are exposed to normal microfluidic flow rates. I have implemented such a dynamic nanochannel approach with a recently-developed microfluidic material based polyethylene glycol diacrylate (PEGDA). I present the design, fabrication, and testing of PEGDA dynamic nanochannel array sensors, and demonstrate an 11.2 % increase in nanochannel impedance when exposed to 7.2 µM bovine serum albumin (BSA) in phosphate buffered saline (PBS). Recently, LOC biosensors for cancer cell detection have been demonstrated based on a combination of dielectrophoresis (DEP) and fluorescence detection. For fluorescence detection it is critical to minimize other sources of light in the system. However, reported devices use a non-noble metal electrode, indium tin oxide (ITO), to take advantage of its optical transparency. Unfortunately, use of non-noble metal electrodes can result in galvanoluminescence (GL) in which the AC voltage applied to the electrodes to achieve DEP causes light emission, which can potentially confound the fluorescence measurement. I designed and fabricated two types of devices to examine and identify conditions that lead to GL. Based on my observations, I have developed a method to avoid GL that involves measuring the impedance spectrum of a DEP device and choosing an operating frequency in the resistive portion of the spectrum. I also measure the emission spectrum of twelve salt solutions, all of which exhibited broadband GL. Finally, I show that in addition to Au, Cr and Ni do not exhibit GL, are therefore potentially attractive as low cost DEP electrode materials.

Dans cette thèse, nous avons travaillé sur la mise au point de surfaces superhydrophobes modèles dont la mouillabilité peut être contrôlée par un stimulus externe. Composées de forêts de piliers micrométriques élastomères à forts rapports d'aspect dans lesquels sont incorporées des particules magnétiques, les surfaces présentent, via l'application d'un champ magnétique externe, une orientation modulable des piliers, donc une rugosité de surface adaptable. En faisant varier la géométrie, l'élasticité et l'aimantation de ces derniers, nous avons pu mettre en évidence les points suivants. Nous avons vu dans un premier temps qu’en accord avec la littérature, et en l’absence de champ magnétique, l’hystérèse de mouillage augmente avec la fraction de surface. Cependant, elle reste constante lorsque l’élasticité des piliers varie. Résultat déroutant, car à l’échelle du pilier, il existe bel et bien une différence de mobilité des piliers entre les piliers les plus rigides et les plus complaisants qui subissent la traction de la ligne triple.Nous avons ensuite montré que l’orientation des piliers changeait significativement l’angle de glissement via l’application d’un champ magnétique. De plus, le glissement de la goutte sur la surface est favorisé lorsque les piliers sont orientés à l’opposé de la pente. Enfin, nous avons pu contrôler la façon dont une goutte d’eau se déplace sur une surface inclinée en deçà de l’angle de glissement, puisqu’elle n’avance vers le bas de la surface que si une actuation magnétique est appliquée. Ces surfaces seront une source d’étude intéressante pour comprendre comment moduler le mouillage ou l’écoulement de liquide en état fakir. / During this thesis, we have developped superhydrophobic surfaces whose wettability can be controlled by an external magnetic stimulus. Formulating a network of elastomeric and magnetic micro-pillars with high aspect ratio allows the orientation of the pillars through magnetic forces, hence an adaptable surface roughness. Moreover, modulating the geometry, elasticity and magnetization of pillars allowed us to highlight the following conclusions.We have seen first that in agreement with the literature, without magnetic field, the wetting hysteresis increased with the surface fraction. However, it remains constant varying the elasticity of pillars. This conclusion is confusing, because at the pillar scale, there is indeed a difference of mobility between rigid and flexible pillars due to the force exerted by the triple line.We then demonstrated that the deflexion of the pillars can change significantly the sliding angle due to the applied magnetic field. Moreover, sliding of the droplet on such a surface is promoted when pillars are deflected against the slope.Finally, we managed to control the displacement of a droplet on a surface which is tilted with an angle below the sliding angle : it moves forward from the surface only if magnetic actuation is applied. This surfaces will be an attractive source of study in order to understand how to modulate wetting and liquid flow in fakir state.