The interest for miniaturisation in chemical and biological analysis has increased in recent years. In this work, the design, fabrication and characterisation of tools for microanalysis have been studied. The focus is set on polymer microchips for applications in chemical analysis. The work consists of three parts: design and fabrication of paraffin microactuators, design and fabrication of polymer microchips as interfaces in electrospray ionisation mass spectrometry (ESI-MS), and characterisation of conducting films for fused silica capillaries as interfaces in ESI-MS. The principle of the paraffin actuators is based on the volume increase resulting from paraffin melting. Paraffin expansion is utilised to cause membrane deflection. The first plastic microactuator using paraffin as the actuator material was successfully demonstrated. The microchips as interfaces in ESI-MS have been designed with the objective that the interface should be as much a part of the microchip as possible, and as to as large extent as possible, be fabricated in the same step as the microchannels. Sheathless electrospray from microchips was demonstrated for the first time. In addition a simplified fabrication process for ESI-MS interfaces in poly(dimethyl siloxane) (PDMS) was developed. The degradation of conductive coatings for sheathless ESI-MS on fused silica capillaries was studied. It was shown that electrochemical experiments could successfully be used to simulate the electrospray conditions and predict the failure of different gold coatings. It was concluded that a common issue in the fabrication of thermoplastic microchips is the crucial sealing of microchannels and cavities. From this point of view, PDMS is a more advantageous material in microfluidics.

Neste trabalho, diferentes tipos de microestruturas foram geradas por torneamento com ferramenta de diamante de ponta única e microendentação para serem replicadas através da prensagem a quente. Testes foram realizados para ser avaliada a geração destas microestruturas por dois métodos distintos: microdeformação e microusinagem, planejados para observar a replicação gerada por marca de endentação Vickers (piramidal) e, remoção de material (torneamento com ferramenta de diamante de ponta única). Uma revisão no processo de manufatura aplicada para a replicação de microestruturas é apresentada. Os materiais usados como molde e réplica foram o cobre eletrolítico e o polimetilmetacrilato (PMMA), respectivamente. Inicialmente, a usinabilidade do cobre eletrolítico foi avaliada sob diferentes condições de corte, a fim de determinar parâmetros apropriados de torneamento para obter um fino revestimento de superfície final (rugosidade). Observou-se que para avanços (f) de 10 mícrons por revolução e profundidade de corte (ap) de 5 mícrons, a superfície apresentou um baixo valor de rugosidade, isto é, 2,81 nm para rugosidade média (Ra) e 13,4 nm para rugosidade teórica (Rt). Além disso, observou-se que a microestrutura do material mostrou-se de fundamental papel na rugosidade, por conta da recuperação elástica dos grãos devido a anisotropia da estrutura policristalina do cobre. As microestruturas geradas para a replicagem foram: a) lente esférica, b) perfil senoidal e sulcos concêntricos. Os resultados mostraram que é viável a reprodução, com boa conformidade das microestruturas, por meio de prensagem a quente. Observou-se que as bordas e as superfícies finas com rugosidade em torno de 10 nm rms foram bem replicadas. / In this work, different types of microstructures were generated by single point diamond turning and microindentation for will replicated through the hot embossing. Tests were carried to evaluate the generation these microstructures by two distinct methods: micro-deformation and micro-machining, planned to observe the replication of the mark generated by the Vickers indenter (Pyramidal) and the latter by material removal (single point diamond turning). A review on several manufacturing processes applied to replication of microfeatures, is presented. The materials used as mould and replication workpiece were electroless copper and polymethylmethacrylate (PMMA), respectively. Initially, the machinability of electroless copper was evaluated under different cutting conditions to determinate appropriate turning parameters to obtain very fine surface finish (roughness). It was observed that for f = 10 microns of revolution (feed rate) and ap = 5 microns (depth of cut), the surface presented the roughness’ lowest value, i.e., 2,81 nm to medium roughness (Ra) and 13,4 nm to theoretical roughness (Rt). Moreover, it was observed that the microstructure of the material plays a fundamental role on roughness, because of the elastic recovery of grains due to the anisotropy of the polycrystalline structure of copper. The microfeatures generated were the following: a) spherical lens, b) sinusoidal profile and concentrical grooves. The results showed that it is feasible to reproduce, with good agreement, the microfeatures by means of hot embossing. It was observed that thin edges and fine surfaces with roughness around 10 nm rms were well replicated.

Neste trabalho, diferentes tipos de microestruturas foram geradas por torneamento com ferramenta de diamante de ponta única e microendentação para serem replicadas através da prensagem a quente. Testes foram realizados para ser avaliada a geração destas microestruturas por dois métodos distintos: microdeformação e microusinagem, planejados para observar a replicação gerada por marca de endentação Vickers (piramidal) e, remoção de material (torneamento com ferramenta de diamante de ponta única). Uma revisão no processo de manufatura aplicada para a replicação de microestruturas é apresentada. Os materiais usados como molde e réplica foram o cobre eletrolítico e o polimetilmetacrilato (PMMA), respectivamente. Inicialmente, a usinabilidade do cobre eletrolítico foi avaliada sob diferentes condições de corte, a fim de determinar parâmetros apropriados de torneamento para obter um fino revestimento de superfície final (rugosidade). Observou-se que para avanços (f) de 10 mícrons por revolução e profundidade de corte (ap) de 5 mícrons, a superfície apresentou um baixo valor de rugosidade, isto é, 2,81 nm para rugosidade média (Ra) e 13,4 nm para rugosidade teórica (Rt). Além disso, observou-se que a microestrutura do material mostrou-se de fundamental papel na rugosidade, por conta da recuperação elástica dos grãos devido a anisotropia da estrutura policristalina do cobre. As microestruturas geradas para a replicagem foram: a) lente esférica, b) perfil senoidal e sulcos concêntricos. Os resultados mostraram que é viável a reprodução, com boa conformidade das microestruturas, por meio de prensagem a quente. Observou-se que as bordas e as superfícies finas com rugosidade em torno de 10 nm rms foram bem replicadas. / In this work, different types of microstructures were generated by single point diamond turning and microindentation for will replicated through the hot embossing. Tests were carried to evaluate the generation these microstructures by two distinct methods: micro-deformation and micro-machining, planned to observe the replication of the mark generated by the Vickers indenter (Pyramidal) and the latter by material removal (single point diamond turning). A review on several manufacturing processes applied to replication of microfeatures, is presented. The materials used as mould and replication workpiece were electroless copper and polymethylmethacrylate (PMMA), respectively. Initially, the machinability of electroless copper was evaluated under different cutting conditions to determinate appropriate turning parameters to obtain very fine surface finish (roughness). It was observed that for f = 10 microns of revolution (feed rate) and ap = 5 microns (depth of cut), the surface presented the roughness’ lowest value, i.e., 2,81 nm to medium roughness (Ra) and 13,4 nm to theoretical roughness (Rt). Moreover, it was observed that the microstructure of the material plays a fundamental role on roughness, because of the elastic recovery of grains due to the anisotropy of the polycrystalline structure of copper. The microfeatures generated were the following: a) spherical lens, b) sinusoidal profile and concentrical grooves. The results showed that it is feasible to reproduce, with good agreement, the microfeatures by means of hot embossing. It was observed that thin edges and fine surfaces with roughness around 10 nm rms were well replicated.

Le procédé d’estampage à chaud est considéré comme l'un des procédés les plus prometteurs de micro-Réplication pour l'élaboration des micro-Composants ou nano-Composants avec des matériaux polymériques dans différents domaines d'application . La mémoire consiste à caractériser les propriétés physiques des polymères thermoplastiques amorphes (PS, PMMA et PC) sur une large plage de température, ainsi que la modélisation physique, la simulation numérique et vérification expérimentale du procédé d’estampage à chaud.[...]Les propriétés visco élastiques des polymères retenus ont été caractérisées avec les essais décompression dynamiques. Le module de conservation, le module de perte et le facteur d'amortissement de polymère PMMA à partir de la température ambiante jusqu'à légèrement au-Dessus de Tg ont été obtenues. Le comportement visco élastique des polymères a été décrit par un modèle de Maxwell Généralisé et un bon accord a été observé. La simulation numérique des étapes du remplissage de procédé d’estampage à chaud a été réalisée enprenant compte des propriétés visco élastiques de polymère. Les effets de la température et dela pression de compression sur l'exactitude de réplication dans le procédé d’estampage à chaud ont été étudiés.[...]Un nouveau moule de compression complet, y compris le système de chauffage, le système de refroidissement et le système de vide a été développé dans notre groupe de recherche. Les dispositifs micro fluidiques avec la dimension de la cavité : environ 200 μm, 100 μm et 50 μmen PS, PMMA et PC plaque (épaisseur de 2 mm) ont été élaborés par le procédé d’estampage à chaud. Les effets des paramètres du procédé, tels que l’entrefer imposé, la température décompression, la matière compressée et la dimension de micro cavité, sur l’exactitude de réplication du procédé d’estampage à chaud ont été étudiés. / Hot embossing process is considered as one of the most promising micro replication processes for the elaboration of micro or nano components with polymeric materials invarious application fields. The thesis consists to characterize the physical properties of widelyused amorphous thermoplastic polymers (PS, PMMA and PC) over a large temperature range,along with the physical modelling, numerical simulation and experimental verification of thehot embossing process.[...] The polymers’ viscoelastic properties have been characterized with the dynamical compression tests. The storage modulus, loss modulus and damping factor of PMMA polymerfrom ambient temperature to lightly above Tg have been obtained. The viscoelastic behaviourof polymer has been described by a proposed Generalized Maxwell model and a good agreement has been observed. The numerical simulation of filling stage of hot embossing process has been achieved by taking into account of polymer’s viscoelastic properties. Theeffect of compression temperature and pressure on the replication accuracy in hot embossing process has been investigated in the simulation.[...] A new complete micro compression mould tools, including heating system, cooling system and vacuum system have been developed in our research group. The microfluidic devices with the cavity dimension eq. to about 200 μm, 100 μm and 50 μm in PS, PMMA and PC plate(thickness eq. to 2 mm) have been elaborated by the hot embossing process. The effects of the processing parameters, such as the compressive gap imposed, compression temperature, embossed material and die cavity dimensions, on the replication accuracy of hot embossing process have been investigated.

No description available.

In vitro, la formation de structures de type tubulaire avec des cellules endothéliales de veine ombilicale humaine (HUVEC) a été étudiée en combinant la fonctionnalisation de la chimie des matériaux et le développement de la géométrie tridimensionnelle. Le polycarbonate (PC) a été utilisé comme modèle pour le développement de l'échafaud. Le film de polysaccharide naturel, basé sur un dépôt alternatif couche par couche (LbL) d’acide hyaluronique (HA) et de chitosane (CHI), a d’abord été appliqué sur une surface PC et caractérisé en termes de croissance d’épaisseur microscopie à balayage lascar (CLSM). Cette première fonctionnalisation se traduit par un revêtement complet de la couche PC. Une biofonctionnalisation supplémentaire avec un peptide adhésif (RGD) et deux peptides angiogénétiques (SVV et QK) a été étudiée, immobilisant ces peptides sur le groupe carboxylique de HA précédemment déposé, en utilisant la chimie bien connue du carbodiimide. La version marquée de chaque peptide a été utilisée pour caractériser l’immobilisation et la pénétration des peptides dans les couches de polyélectrolytes, aboutissant à une greffe réussie avec une pénétration complète dans toute l’épaisseur du LbL. Des tests in vitro ont été effectués à l'aide de cellules HUVEC pour évaluer leur efficacité d'adhésion et leur activité métabolique sur la LbL avec et sans immobilisation de peptides, ce qui a permis d'améliorer l'activité préliminaire lorsque des combinaisons de peptides sont utilisées. Enfin, les micro-canaux PC (μCh) ont été développés et caractérisés pour la première fois, et les autres expériences ont été réalisées sur un micromètre de 25 μm de largeur, fonctionnalisé avec une architecture (HA / CHI) 12,5 (PC-LbL) avec des peptides RGD et QK -RGD + QK) ou avec des peptides RGD et SVV (PC-RGD + SVV). Notre première expérience de tubulogénèse a montré de manière surprenante la formation de structures de type tubulaire déjà après 2h d'incubation en utilisant la combinaison double-peptides, mais uniquement avec PC-RGD + QK. Les tubes étaient également présents après 3 et 4 heures de culture. L'expérience de co-culture avec des péricytes humains dérivés du placenta (hPC-PL) montre comment la stabilisation des tubes a été améliorée après 3 et 4 heures également pour l'échantillon de PC-RGD + SVV. Globalement, notre matériel bio-fonctionnel avec les peptides PC-RGD + QK et PC-RGD + SVV permet la formation d'une structure de type tubulaire à la fois dans une expérience de monoculture et de co-culture. / In vitro, tubular-like structures formation with human umbilical vein endothelial cells (HUVECs) was investigated by combining material chemistry functionalization and three-dimensional geometry development. Polycarbonate (PC) was used as a template for the development of the scaffold. Natural polysaccharide’s film based on alternate layer-by-layer (LbL) deposition of hyaluronic acid (HA) and chitosan (CHI), was first applied to PC surface and characterized in terms of thickness growth both, in dry conditions using ellipsometry, and confocal lascar scanning microscopy (CLSM). This first functionalization results in a complete coating of the PC layer. Further biofunctionalization with one adhesive peptide (RGD) and two angiogenetic peptides (SVV and QK) was investigated, immobilizing those peptides on the carboxylic group of HA previously deposited, using the well-known carbodiimide chemistry. The labeled version of each peptide was used to characterize the peptides’ immobilization and penetration into the polyelectrolytes layers, resulting in a successful grafting with complete penetration through the entire thickness of the LbL. In vitro tests were performed using HUVECs to assess their adhesion efficiency and their metabolic activity on the LbL with and without peptide immobilization, resulting in a preliminary improved activity when peptide-combinations is used. Finally, PC micro-channels (μCh) were first developed and characterized, and the rest of the experiments were performed on μCh of 25μm width, functionalized with (HA/CHI)12.5 architecture (PC-LbL) with RGD and QK peptides (PC-RGD+QK) or with RGD and SVV peptides (PC-RGD+SVV). Our first tubulogenesis experiment surprisingly showed the formation of tubular-like structures already after 2h of incubation using the double-peptides combination but only using PC-RGD+QK the tubes were present also after 3 and 4 hours of culture. The co-culture experiment with human pericytes derived from placenta (hPC-PL) demonstrates how the stabilization of the tubes was improved after 3 and 4 hours also for the PC-RGD+SVV sample. Globally our bio-functional material with PC-RGD+QK and PC-RGD+SVV peptides allow the formation of tubular-like structure in both mono and co-culture experiment.

This work investigates the Fresnel-lens-based solar concentrator-receiver system in a multi-perspective manner to design, test and fabricate this concentrator with high-efficiency photon and heat outputs and a minimized effect of chromatic aberrations. First, a MATLAB®-incorporated algorithm optimizes both the flat-spot and the curved lens designs via a statistical ray-tracing methodology of the incident light, considering all of its incidence parameters. The target is to maximize the solar ray intensity on the receiver's aperture, and therefore, achieve the highest possible focal flux. The algorithm outputs prismatic and dimensional geometries of the Fresnel-lens concentrator, which are simulated by COMSOL® Multiphysics to validate the design. For the second part, a novel genetically-themed hierarchical algorithm (GTHA) has been investigated to design Fresnel-lens solar concentrators that match with the distinct energy input and spatial geometry of various thermal applications. Basic heat transfer analysis of each application decides its solar energy requirement. The GTHA incorporated in MATLAB® optimizes the concentrator characteristics to secure this energy demand, balancing a minimized geometry and a maximized efficiency. Two experimental applications were selected from literature to validate the optimization process, a solar welding system for H13 steel plates and a solar Stirling engine with an aluminum-cavity receiver attached to the heater section. In each case, a flat Fresnel-lens with a spot focus was algorithmically designed to supply the desired solar heat, and then a computer simulation of the optimized lens was conducted showing great comparability to the original experimental results. Thirdly, the prismatic geometry of the Fresnel lens was further optimized through a statistical approach that incorporates laws of light refraction and trigonometry. The proposed design produces high focal irradiance that is more suitable for thermal applications. The motivation was to enhance the tolerability of a flat Fresnel-lens concentrator to tracking errors, without the use of secondary optics or sophisticated, and normally costly, meticulous tracking equipment. A comparative simulation analysis was conducted for two case studies from literature, each with a different design method. Fresnel lenses optimized by this work enhanced the concentration acceptance product (CAP) significantly, compared to that in literature. Then, this work introduced an innovative code-based, detailed, and deterministic geometrical approach, which couples the optimization of the Fresnel lens primary optical element (POE) and the dome-shaped secondary optical element (SOE). The objective was to maximize the concentration acceptance product, while using the minimum SOE and receiver geometries at a given f-number and incidence angle (also referred to as the tracking error angle). The laws of polychromatic light refraction along with trigonometry and spherical geometry were utilized to optimize the POE grooves, SOE radius, receiver size, and SOE–receiver spacing. Two literature case studies were analyzed to verify this work's optimization, and the equivalent POEs designed by this work, with optimized SOEs, showed a significant enhancement in the CAP values compared to that of literature. Lastly, four methods for prototyping the Fresnel lens were discussed and experimentally tested; 3D printing, acrylic resin casting, direct CNC machining in acrylic and hot embossing. Once tested, the methods of CNC machining and hot embossing of acrylic proved to be the most promising in terms of cost, fabrication time, and concentration effectiveness. Future work will focus on enhancing the algorithmic design and improving the quality of lens fabrication.

Les travaux menés dans le cadre de cette thèse sont focalisés sur les procédés deréplication permettant la transformation des mélanges en composants par les technologiesen séquentiel ou bien en continu, selon les applications visées. Les développementsconcernent la mise en place et l’hybridation de différents procédés de micro-réplication(estampage à chaud de polymère thermoplastique et par laminage circulaire entre deuxrouleaux). Ces deux procédés sont développés et optimisés pour l’élaboration decomposants micro-structurés ou de microcomposants possédant des propriétésfonctionnelles mécaniques ou thermo-physiques requises à partir de différents mélangeschargés en poudres métalliques ou en nanotubes de carbone. Des exemples de réalisationde composants structurés, à base d’un système micro-fluidique possédant plusieurs canauxde 200 microns par 200 microns et des réservoirs de diamètre de 2 mm, sont prises commeexemple tout au long de ces travaux de cette thèse. Différents travaux de caractérisationsont été entrepris pour optimiser les procédés de micro-réplication par estampage à chaud etpar laminage circulaire entre deux rouleaux. / The Ph.D subject concerns the study of two micro-replication processes by hotembossing and roll to roll processes for thermoplastic polymers and loaded polymers withpowders or carbon nanotubes. The micro-replication processes, realized in sequential orcontinuous ways, use some different elaborated loaded feedstocks in order to obtainstructural components or micro-component with high aspect ratio and mechanical orthermo-physical properties.A chain combining hot embossing and roll embossing and powder metallurgy have beendeveloped in our lab and investigated. The different micro mould die cavities have beenrealized with different micro-manufacturing process, elastomeric mould has been obtainedby casting process. Finally, a metallic structured die cavity has been obtained by combininghot embossing and debinding and sintering stages. The second topic is the comparison ofmetallic die cavity mould obtained by roll embossing or rolls embossing. Two demonstratorshave been developed during the preparation of this Ph.D period: first a metallic micro-fluidicsystem with micro-structuration with diameter of 1 mm for the reservoir and 200 microns by200 microns for the channel have been realized and characterized by different methods.Secondly, some functional micro-component has been obtained with carbon nanotube andsome specific properties in terms of mechanic and thermo-physical properties have beencharacterized.

Increasingly compact and powerful light emitting diodes require the development of efficient optical diffusers to manage their lighting capability according to the required application. In this study, a cost-effective strategy is demonstrated for fabricating micro-structured polymethylmethacrylate (PMMA) diffusers for white light sources. By combining different laserbased processes, namely direct laser engraving (DLE), direct laser writing (DLW), and direct laser interference patterning (DLIP), periodic patterns are fabricated in stainless steel surfaces with line- and dot-like geometries with feature sizes ranging from 1.7 to 900 μm. The fabricated hierarchical geometries are transferred to PMMA surfaces by plate-to-plate hot embossing. The relationship between the surface topography and the white light scattering behavior is investigated by confocal and scanning electron microscopy combined with photospectroscopy and image processing of photographs. The triple-scaled hierarchical structures can increase the haze up to 76% in the visible spectrum, while keeping the total transmittance over 90%, as the flat surface.