Ce mémoire de maîtrise traite des circuits actifs amplificateurs dont la conception est faite spécialement pour qu'ils soient intégrés aux métamatériaux électromagnétiques, en particulier à une antenne à ondes de fuite CRLH (Composite right/left-handed). Cette antenne a la particularité de pouvoir varier la direction de son rayonnement sur près de 180 degrés, en changeant simplement la fréquence du signal émis. Par conséquent, elle est une candidate de choix pour les applications radars. Toutefois, étant donné que son gain est relativement faible, des amplificateurs ont été ajoutés entre certaines de ses sections pour créer une antenne active CRLH [Casares-Miranda et al. , 2006]. Malheureusement, cette dernière n'est optimisée que pour une seule fréquence, donc pour un rayonnement dans une seule direction. Lobjectif de ce projet est donc la conception d'amplificateurs qui permettraient que cette antenne active ait un rayonnement optimal à toutes les fréquences. Dans ce texte, la théorie générale des métamatériaux est expliquée pour ensuite se concentrer sur les caractéristiques de l'antenne à ondes de fuite CRLH. Une étude de celle-ci est complétée de manière a déterminer les spécifications nécessaires des circuits amplificateurs qui y seront intégrés. Il est ainsi indiqué que pour fabriquer une antenne à ondes de fuite active idéale, les amplificateurs devraient avoir un gain constant sur toute la bande. Aussi, le déphasage introduit par ceux-ci doit être le plus constant possible sur toute cette bande, donc le délai de groupe de ces circuits doit être minimum. Cependant, un fait intéressant qui est amené par cette étude est qu'en intégrant des déphaseurs dans les circuits amplificateurs, il est possible de fabriquer une antenne à ondes de fuite CRLH active dont on peut obtenir une grande variété de diagrammes de rayonnement sur toute la plage de fréquences. Par conséquent, l'étude, la conception et la fabrication de circuits amplificateurs et déphaseurs sont discutées. Ces circuits sont faits avec des MESFET.

The present thesis work deals with the development of a novel manufacturing protocol for the realization of excimer laser micro-patterned freestanding hydrogel layers (50 to 300 ??m thickness) based on thermo-responsive poly-(N-isopropyl)acrylamide (PNIPAAm) which can operate as temperature-triggered actuators for cells-on-chip applications. PNIPAAm based thin films were synthesized in house and manufactured by an injection/compression moulding based technique in order to obtain flat hydrogels attached to rigid polyvinyl chloride (PVC) substrates to facilitate laser focusing. Laser machining parameters were empirically optimized to fabricate arrays of through-holes with entrance diameter ranging from 30 ??m to 150 ??m and having different exit diameter (from 10 to 20 ??m) on the PNIPAAm employing a stencil aluminum mask. After laser processing, the microstructured layers were detached from the PVC using a chemical treatment and then left to swoll in pure water. The KrF excimer laser machined through-holes could be reversibly modulated in terms of size as a consequence of the polymer volumetric phase transition induced by a temperature change above the critical value of 32 ??C. Thermo-responsiveness characterization was carried out on the detached water swollen freestanding layers using a thermostat bath, by changing the temperature from 18 ??C to 39 ??C and each sample could undergo multiple cycles. As a result of the polymer water loss, the shrinkage of the layer caused the holes to shrink homogeneously, thus reducing their original size of about the 50% in the polymer collapsed state. To prove the functionality of these stimuli-responsive smart surfaces in the frame of cells-on-chip systems, they were integrated in a multilayer microfluidic device to operate as self-regulating cell sorting actuators for single cell assays applications. Using mechanical fastening as the packaging strategy, the hydrated hydrogel was sealed between two micro-milled poly-methyl methacrylate (PMMA) components, which provided the fluid accesses and ducts to the cell suspension to be flown over the thermoresponsive actuator (top layer) and the well to collect the sorted sample (bottom layer). The device is also equipped with a thin transparent heater to control the microfluidic chip temperature. When the system is assembled, the temperature-triggered actuation mechanism was exploited to trap a cellular sample in the shrunken exit hole on the top of the hydrogel layer by applying a negative pressure across the film via the bottom PMMA component when the system is kept at 37 ??C. Subsequently, the sorting of the trapped cell took place through the micro-capillary when the polymer natural relaxation at room temperature towards its initial state occurred; the operational principle of the device was proved using MG63 cells as a model cell line by monitoring the sorting through the size-modulating structures using optical microscopy.

We have investigated electropolymerisation for fabrication of a chemically modified working electrode for the determination of dopamine and catechol neurotransmitters in the presence of ascorbic acid. A variety of film compositions were investigated that would allow discrimination of the neurotransmitters through a combination of electrostatic barrier and the film porosity. The films investigated were based on different compositions of () poly-o-toluidine-co-aniline (POT-co-PA), () poly-o-toluidine-co-o-anisidine (POT-co-POA) and () polyacriflavine (PAF). The POT-co-PA and POT-co-POA gave the most promising result although the POT-co-PA was preferred because of higher current enhancement and better separation of dopamine and catechol neurotransmitters in the presence of ascorbic acid. The uses of electropolymerisation make the investigated films attractive candidates for the fabrication of a chemically modified microelectrode with application in capillary electrophoresis separation with electrochemical detection. The active area of nano particle (Au, Pt and Ag) screen printed electrodes was determined using cyclic voltammogram with ferro/ferricyanide couple. The active surface of the nano particle coated electrode was found surprisingly to be 5% - 65% lower than that geometrically calculated surface area for the electrode. This is ascribed to the limitation of the screen printing approach that was used. A low cost high replication approach that would allow development of a capillary electrophoresis microfluidic chip with electrochemical detection (CE-ECD) on a polymer substrate was investigated. A fluidic top layer was fabricated using hot embossing and an electrode bottom layer by metal patterning on a polymer substrate using metallisation and photolithography.

L'évolution vers le monde des nanotechnologies croît actuellement très rapidement. Ces technologies sont présentes dans de nombreux secteurs d'activités allant de l'automobile à la recherche, mais sont encore bien méconnues dans leurs aspects fondamentaux du domaine industriel et scientifique. Nombreux sont les process industriels faisant appel à la température : chauffage, cuisson, traitement thermique, fusion, etc. Les procédés mis en œuvre pour la contrôler et la réguler forment un ensemble complet, la chaîne de mesure thermique. En première ligne, au cœur du process, le capteur constitue l'élément sensible de cette chaîne. Depuis un demi siècle, les techniques de microscopies évoluent pour caractériser la matière et comprendre les phénomènes locaux. Afin de mieux maîtriser cette compréhension les microscopies thermiques ont vu le jour pour déterminer également à l'échelle locale la température afin de connaître le niveau d'énergie. La sonde utilisée est également au cœur du problème. La conception jusqu'au développement de cette nouvelle sonde s'appuie sur des technologies hybrides basées sur des techniques de dépôts en salles blanches ainsi que sur des techniques classiques d'élaboration de thermocouples. La sonde réalisée, certes intrusive, permet d'allier la mesure de températures aux contacts de matériaux et d'offrir la possibilité d'être une sonde active. Elle pourra notamment compléter les sondes actuellement proposées en microscopie de champ proche.

Mask Projection Stereolithography (MPSLA) is a high resolution manufacturing process that builds parts layer by layer in a photopolymer. In this research, a process planning method to fabricate MPSLA parts with constraints on dimensions, surface finish and build time is formulated. As a part of this dissertation, a MPSLA system is designed and assembled. The irradiance incident on the resin surface when a given bitmap is imaged onto it is modeled as the Irradiance model . This model is used to formulate the Bitmap generation method which generates the bitmap to be imaged onto the resin in order to cure the required layer. Print-through errors occur in multi-layered builds because of radiation penetrating beyond the intended thickness of a layer, causing unwanted curing. In this research, the print through errors are modeled in terms of the process parameters used to build a multi layered part. To this effect, the Transient layer cure model is formulated, that models the curing of a layer as a transient phenomenon, in which, the rate of radiation attenuation changes continuously during exposure. In addition, the effect of diffusion of radicals and oxygen on the cure depth when discrete exposure doses, as opposed to a single continuous exposure dose, are used to cure layers is quantified. The print through model is used to formulate a process planning method to cure multi-layered parts with accurate vertical dimensions. This method is demonstrated by building a test part on the MPSLA system realized as a part of this research. A method to improve the surface finish of down facing surfaces by modulating the exposure supplied at the edges of layers cured is formulated and demonstrated on a test part. The models formulated and validated in this dissertation are used to formulate a process planning method to build MPSLA parts with constraints on dimensions, surface finish and build time. The process planning method is demonstrated by means of a case study.

This report discusses the use of micro-fabrication techniques for creating experimental test sections containing trees of micro-finned conducting pathways, also referred to as constructal trees, for cooling a heat generating substrate. These trees are made of copper and contain branches that bifurcate at 90° angles to form constructal patterns. The patterns for the finalized test sections were created using photolithography techniques, and copper was deposited via thermal evaporation onto a 1 cm² substrate to create the trees. Certain test section design parameters were varied including the geometric complexity of the constructal trees, the volume of copper used between tree complexities, choice of material for the substrate, and the height, or thickness, of the trees. Also described in this report is an experimental methodology and testing apparatus designed to assess the cooling performance of the test sections. This methodology includes using controlled uniform heating applied to the bottom of each test section, while cooled nitrogen is impinged on the tip of the constructal tree to create a heat sink. / text

Microfluidic devices have found applications in a number of areas, such as medical analysis, chemical synthesis, biological study, and drug delivery. Because of the small channel dimensions used in these systems, most microchannels exhibit laminar flow due to their low Reynold’s number, making mixing of fluids very challenging. Mixing at this size scale is diffusion-limited, so inducing chaotic flow patterns can increase the interface surface area between two fluids, thereby decreasing overall mixing time. One method to create a chaotic flow within the channel is through the introduction of internal protrusions into the channel. In such an application protrusions that create a rotational flow within the channel are preferred due to their effectiveness in folding the two fluids over one another. The novel mixer outlined in this paper uses a Ti-Ni shape memory alloy for the creation of protrusions that can be turned controlled through material temperature. Controllability of the alloy allows users to turn the chaotic flow created by the protrusions off and on by varying the temperature of the mixer. This ability contributes to the idea of a continuous microfluidic system that can be turned on only when necessary as well as recycle unmixed fluids while turned off.

Breast implant capsular contracture (CC) formation is a significant clinical complication post augmentation/reconstruction, which often necessitates re-operation. CC, which occurs in over half of patients post augmentation, is the formation of a fibrous internal capsule which constricts around the prosthesis leading to firmness, deformity and pain. The pathoetiology of CC is poorly understood with minimal understanding of the triggers, signalling pathways or dysregulated genes implicated in its formation. Therefore, the first aim of the present thesis was to investigate biomarkers implicated in CC formation, through whole genome microarray, quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and immunohistochemistry (IHC) on capsule samples ranging from normal capsules (Baker Grade 1) to severely contracted capsules (Baker Grade 4). After targeted enrichment analysis, microarray identified 6 genes which were significantly dysregulated in contracted capsules. After further genomic and proteomic validation, two potential diagnostic, prognostic or therapeutic biomarkers for CC, interleukin 8 (IL8) and tissue inhibitor of metalloproteinase 4 (TIMP 4), were identified as being significantly dysregulated in CC. However, the role of each of the multiple cell types which populate a contracted capsule has yet to be determined. Therefore, the role of capsular fibroblasts was investigated using immunocytochemistry, qRT-PCR, cytokine arrays and a fibroblast populated 3D collagen matrix. IL8 and TIMP were investigated, in addition to other pro-fibrotic and pro-inflammation related candidates, to identify the role of breast capsule fibroblasts in CC formation. Normal breast fibroblast populated collagen matrices were significantly more contracted after supplementation with contracted-capsule fibroblast conditioned media, in comparison to normal growth media. It was discovered that breast-derived fibroblasts were potentially instigating and/or perpetuating CC through the transformation of normal breast fibroblasts into contracted capsule fibroblast like cells, via a paracrine signalling mechanism. The results of this work on capsular fibroblasts, and the previous work on capsular tissue, increased our understanding of the cell types and signalling molecules which are dysregulated leading to CC formation. Therefore, a novel silicone implant surface potentially capable of averting CC formation could be fabricated. Acellular dermal matrix (ADM) has been used as an adjunct in breast implant augmentation/reconstruction resulting in reduced rates of CC formation. Therefore, the micro and nanoscale topography of ADM was reproduced in a silicone surface, through a novel fabrication technique utilising comprehensive characterisation of ADM with atomic force microscopy (AFM), maskless grayscale photolithography, modified deep reactive ion etching (DRIE) and replica moulding. The features of ADM were successfully re-created in silicone to within 5 nm (Sa) and 655 nm (Sz), at a length scale of 90x90 µm2. Biological evaluation revealed that ADM PDMS surfaces promoted cell adhesion, proliferation and survival when compared to commercially available implant surfaces while cell adhesion regulating genes were upregulated and pro-inflammatory/pro-fibrotic related genes were downregulated. A reduced inflammatory cytokine response was also observed. This study demonstrates that biomimetic prosthetic implant surfaces might significantly attenuate the acute in vitro foreign body reaction to silicone. In conclusion, the results of the present thesis have enhanced our knowledge and understanding of the pathological cellular and molecular mechanisms leading to CC, in addition to the design and development of a novel, biomimetic implant surface that is potentially capable of averting the identified pathological processes in vivo.

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No. of bitstreams: 2 Dissertação - Thiago Miguel Garcia Cardoso - 2014.pdf: 3179587 bytes, checksum: 5d358a40aa90ef1768cbb11668a1a1db (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2014-12-12 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / This current study describes the development of alternative technologies for the fabrication of microfluidic paper-based analytical devices (μPADs). The first technology refers to the manufacturing of a metal stamp for rapid prototyping of μPADs. Basically, the method uses the heating process to transfer wax to the paper surface. The wax is required to create a hydrophobic barriers thus delimiting microfluidic channels for the fluid transport through lateral flow effect. Some remarkable advantages of the metal stamping process include robustness, portability and simplicity. Paraffin is a hydrophobic and thermoplastic material that can be easily molded. Furthermore, it shows high chemical resistance when exposed to different aqueous and organic solutions. The stamping-based technology allows the fabrication of μPADs at very low cost. The proposed approach exhibited great reproducibility. The relative standard deviation (RSD) for the channel widths measured on 50 independent μPADs revealed a value of 3.5%. The analytical performance of the paper-based device associated with colorimetric detection was tested for the nitrite analysis in clinical, food and environmental samples. The limit of detection (LD) nitrite assays without preconcentration was 11.3 μM. In order to access the nitrite concentration in environmental samples, a preconcentration method was developed allowing to achieve a LD of 5.6 μM. The results obtained were compared to the spectrophotometric technique and the statistical test demonstrated no significant difference between both methodologies. The stamping process have demonstrated high potential to produce μPADs in laboratories with none or minimal instrumentation. Besides the stamping process, another fabrication approach based on the spraying of white glue mixed with a sensitizing agent was also proposed to produce μPADs. To create effective hydrophobic barriers, the white glue was first sprayed on the paper surface though a magnetic mask. Afterwards, the device was exposed to visible light for polymerization of the glue. In order to evaluate the fabrication methodology, 25 devices were produced and the RSD value achieved for the channel widths was 5.7%. The analytical feasibility of the μPADs fabricated with white glue was successfully demonstrated for qualitative assays dedicated to urinalysis (glucose, uric acid, nitrite, pH, BSA, urea, ketones bodies and bilirubin) and pancreatitis assay (amylase and lipase). Both alternative methods based on stamping and spraying has exhibited great potential to be used for production in mass. Moreover, the proposed devices revealed high potential to be broadly explored in biological/clinical, food and environmental applications. / O presente trabalho descreve o desenvolvimento de tecnologias alternativas para fabricação de dispositivos microfluídicos em papel. A primeira tecnologia se refere à confecção de um carimbo metálico para prototipagem de dispositivos microfluídicos em papel. Basicamente, a metodologia baseiase na transferência de parafina para a superfície do papel por um processo de aquecimento. O uso da parafina faz-se necessário para criação da barreira hidrofóbica, no qual delimita canais microfluídicos para o transporte do fluido através do fluxo lateral. As vantagens em utilizar o carimbo estão entre a facilidade de manuseio, a robutez e a portabilidade. Em relação ao uso da parafina, destaca-se como sendo um agente hidrofóbico e termoplástico, que pode ser facilmente moldado, além de ser um material altamente resistente a diferentes compostos químicos. A combinação do uso desses dois materiais, carimbo e parafina, possibilitou a fabricação rápida e barata dos dispositivos microfluídicos à base de papel (μPADs). Para avaliar o desempenho do processo de carimbagem foram fabricados 50 dispositivos no qual o desvio padrão relativo (DPR) encontrado para a largura do canal foi de 3,5%. O desempenho analítico dos μPADs associado a detecção colorimétrica foi avaliado na análise de nitrito em amostras clínicas, alimentícias e ambientais. O limite de detecção da análise de nitrito sem etapa de pré-concentração foi de 11,3 μM, para a análise de amostras ambientais foi desenvolvido uma etapa de pré-concentração, onde foi obtido um limite de detecção de 5,6 μM. Os resultados obtidos foram comparados à técnica de espectrofotometria e o teste estatístico demonstrou que não existe diferença significativa entre os dois métodos. O método de carimbagem demonstrou potencialidade para fabricação dos μPADs em laboratórios com recursos limitados, pois exige um mínimo de instrumentação. Além do processo de carimbagem, uma outra metodologia, também de baixo custo, foi explorada para fabricação dos μPADs. Essa medologia consiste no jateamente de cola branca misturada a um agente sensibilizante serigráfico para fabricação da barreira hidrofóbica. Basicamente, o processo consiste em jatear essa mistura sobre o substrato de papel que foi fixada a uma máscara magnética. Após o jateamento, o dispositivo foi exposto à radiação visível para polimerização da cola e obtenção das barreiras hidrofóbicas. A reprodutibilidade da largura dos canais foi avaliado em 25 microdispositivos e DPR encontrado foi de 5,7%. A potencialidade dos μPADs fabricados por essa metodologia foi avaliada na aplicação em teste para urinálise (glicose, ácido úrico, bilirrubina, nitrito, pH, albumina, ureia e corpos cetônicos) e pancreatite (amilase e lipase). Os dois métodos alternativos de fabricação apresentaram-se viáveis para fabricação dos μPADs e com grande potencialidade para produção em escala industrial. Além disso, demonstraram-se aplicáveis para análise biológicas, alimentícias e ambientais.

Le travail de thèse a consisté à développer des voies originales de microfabrication pour laconception d’électrodes qui pourront être utilisées dans un biocapteur basé sur unetransduction électrochimique. Une des perspectives étant de pouvoir intégrer ce type decapteur dans un microsystème analytique à base microfluidique, nous avons fait le choix duverre comme matériau de base. Par ailleurs, nous avons privilégié les technologies de« lithographie douce » au détriment de voies classiques telles que la photolithographie afin derendre inutile l’accès à des salles à environnement contrôlé ou l’utilisation d’appareillagessophistiqués.Lors de ce travail, nous avons plus particulièrement travaillé sur le développement deméthodes combinant la technique de microtamponnage et la métallisation chimique de typeautocatalytique (electroless). Cette métallisation nécessitant des surfaces catalytiques pourfaire croître la couche métallique, nous avons développé des méthodes de traitements desurface afin de rendre le substrat de base catalytique sur toute sa surface. La technique demicrotamponnage a ensuite été utilisée afin de passiver les zones où la métallisation n’est pasdésirée et cela a mené à des microstructures métalliques en surface du verre présentant peu oupas de défauts. Notre approche nous a conduit à utiliser plusieurs types de catalyseurs sous laforme de nanoparticules métalliques à base d’argent, d’or ou de palladium et nous avonsdiscuté les différences entre les méthodes basées sur ces différents catalyseurs.Une autre voie a consisté à graver de façon localisée des couches minces métalliquesuniformes en protégeant les zones ne devant pas être gravées par la technique demicrotamponnage. Ceci a permis le développement de deux voies originales demicrostructuration sur couches minces métalliques uniformes (d’une part le pelage sélectif etd’autre part le procédé à double inversion).Dans l’ensemble de nos travaux, des caractérisations d’extrême surface par les techniquesSEM, AFM, ToF-SIMS, XPS et de mouillabilité ont été menées afin d’optimiser ledéveloppement des différents procédés. / This thesis work consisted in the development of original strategy for the microfabrication ofelectrodes which could be used in a biosensor as an electrochemical transducer. One of theprospects of this work is to insert this type of sensor into a microfluidic chip, We have madethe choice of using glass as a substrate. Moreover, we have favoured soft lithographictechnologies at the expense of conventional strategy like photolithography.In this work, we mainly worked on the development of methods which combines microcontact printing and autocatalytic metallisation (electroless). As this type of metallisationneeds catalytic surfaces to grow the metallic layer, we developed surface treatments methodsto make the surface of the substrate catalytic for the metallisation. To follow, the microcontact printing technique has been used to passivate areas where metallisation should notoccur and this leads to metallic microstructure with very few defects. Our approach leads uson the use of different catalyst like gold, silver or palladium nanoparticles and we havediscussed differences between the different methods.Another strategy consisted in the selective etching of thin metallic layer. Areas not to be etchare protected by the micro contact printing technique. This leads to the development of twooriginal strategies of microfabrication on thin metallic layer.In the whole work, extreme surface characterisation like SEM, AFM, ToF-SIMS, XPS andwettability have been carried out in order to optimize the development of the differentmethods.