La demande croissante d’électricité, notamment renouvelable, entraîne une croissance de l’éolien avec l’utilisation de pales en composite de plus en plus grandes. Pour réduire le cout de maintenance de ces structures composites, le suivi de santé structurel (SHM) au cours du temps permet d’évaluer le comportement de la structure, d’anticiper les dégradations et la maintenance. Dans ce cadre, le développement de capteurs, à base de résine époxy et de nanotubes de carbone, appelés Quantum Resistive Sensor (QRS), est présenté. Les QRS peuvent être attachés à la surface de la structure ou intégrés à cœur durant la séquence de drapage. Durant la polymérisation de la résine, le comportement électrique du QRS traduit l’évolution de la réticulation et de la température dans la structure. Suite au processus de fabrication, l’influence des paramètres extérieurs (température, humidité, vitesse de déformation, coefficient de Poisson…) sur les caractéristiques des QRS a été étudiée. Durant l’utilisation de la structure composite, les QRS ont également permis la détection et la propagation d’endommagements jusqu’à la fracture ultime. Les QRS représentent donc une solution potentielle comme capteurs SHM non intrusifs, permettant un suivi de la structure, de sa fabrication jusqu’à sa dégradation finale. / The growing demands for electrical energy, especially renewable, is boosting the development of wind turbines equipped with longer composite blades. To reduce the maintenance cost of such huge composite parts, the structural health monitoring (SHM) is an approach to anticipate and/or follow the structural behaviour along time. To do so, a proper instrumentation is necessary and has to be as less intrusive as possible. To this end, the development of carbon nanotube- epoxy Quantum Resistive Sensor (QRS) is presented. QRS can be as well glued on the surface or embedded in the core of the composite structure during the stacking sequence. During manufacturing, both the temperature and resin crosslinking can be detected with the change in the QRS electrical characteristics. Once the structural part is made, the effect of the external parameters (strain rate, temperature, humidity, Poisson ratio…) on the electrical characteristics of QRS has been studied. During the composite life, the QRS electrical behaviour has also demonstrate its capability to detect the initiation and propagation of damage until final failure. A non-intrusive monitoring with QRS of the structure life cycle, from manufacturing until final breakage is therefore possible.

Orientador: Luis Vicente de Andrade Scalvi / Banca: Margarida Juri Saeki / Banca: Tomaz Catunda / O Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi da Unesp / Resumo: A proposta deste trabalho é a investigação das propriedades elétricas e ópticas de filmes finos de dióxido de estanho (Sn'O IND. 2') obtidos via sol-gel e por solução alcoólica depositados via dip-coating, e, filmes de alumina ('Al IND. 2''O IND. 3') obtidos por deposição de filmes de alumínio (Al) via evaporação resistiva e tratamento térmico em diferentes ambientes, para promover a oxidação de Al. A investigação individual quanto às propriedades ópticas e elétricas desses materiais conhecer seu comportamento na forma de filmes, e estudar a região interfacial de Sn'O IND. 2' e 'Al IND. 2''O IND. 3'. As caracterizações estruturais dos filmes foram feitas por difração de raios-X (DRX), e, no caso dos filmes de alumina, utilizou-se também microscopia eletrônica de varredura (MEV) e microscopia óptica. Nas caracterizações ópticas foram utilizadas técnicas de espectroscopia na região do ultravioleta e no infravermelho próximo (UV-Vis-Nir). Tanto os filmes obtidos por meio alcoólico como obtidos via SGDC foram caracterizados como sendo de Sn'O IND. 2' de estrutura tetragonal do tipo rutilo, sendo que os filmes obtidos via processo alcoólico apresentaram condutividade elétrica maior do que os filmes obtidos via SGDC. Os resultados referentes aos filmes finos de alumínio indicam que independentemente da quantidade de camadas de alumínio depositadas e da atmosfera de tratamento térmico, tem-se a oxidação do alumínio à alumina ('Al IND. 2''O IND. 3'), sendo que a estrutura dominante depende da atmosfera de tratamento. A sua utilização como camada isolante no gate em dispositivo metal-óxido-semicondutor é viável, pois a corrente fonte-dreno apresenta valores significativamente maiores do que a corrente fonte-gate. / Abstract: The main goal of this work is the investigation of properties of tin dioxide (Sn'O IND. 2') and alumina ('Al IND. 2''O IND. 3) thin films. The first one was obtained through the sol-gel process as well as alcoholic solution, via dip-coating. The alumina thin films were obtained by resistive evaporation of aluminum (Al) followed by thermal annealing in distinct atmospheres, to promote the Al oxidation. The individual investigation of optical and electrical properties of these materials aims the knowledge of their behavior as thin films, which allows studying the interface layer of the heterojunction Sn'O IND. 2' e 'Al IND. 2''O IND. 3'. Structural characterization of films was carried out by X-ray diffraction (XRD) technique and particularly on the alumina films, scanning electron microscopy (SEM) and optical microscopy were done. For the optical characterization, wide spectra were obtained, with spectroscopy from ultraviolet to near infrared (UV-Vis-Nir). Either the films obtained in the alcoholic solution as well as via SGDC, where characterized as Sn'O IND. 2' of tetragonal structure of rutile type, and the films obtained through alcoholic process present electrical conductivity higher than the films obtained via SGDC. Results on aluminum thin films indicate that independent on the amount of deposited aluminum and thermal annealing atmosphere, the oxidation of aluminum to alumina ('Al IND. 2''O IND. 3) takes place, but the dominant alumina structure depends on the thermal annealing atmosphere. Besides, its utilization as insulating layer at the gate of a metal-oxide semicondutor device is achievable, because the source-drain current is significantly higher than the source-gate current. / Mestre

In recent years there has been an increased drive towards point of care testing (POCT), in which assays are performed at the site of the patient. This has many benefits, critically; the time for a result to be obtained will be significantly reduced, allowing for greater and more effective decision making. Many currently used bioassay methods are not affordable in resource poor areas where infectious disease is most prevalent, in order to combat this issue many research groups are attempting to miniaturise equipment for portability and make assays more affordable and therefore more accessible. With the aims of generating a new assay platform which is highly portable and affordable, the work in this thesis presents the development of several generic methods utilising nano- and micro-scale beads coated with aptamer which are then monitored interacting with target proteins with Tunable Resistive Pulse Sensing (TRPS). Aptamers are short oligonucleotide sequences which are capable of binding to a wide range of targets with high selectivity and comparable affinity to antibodies while possessing greater stability and have begun to challenge the role of antibodies. When aptamers bind a target, they often undergo a conformational change. In the assays described herein, this conformational change is key to the observed signal changes. TRPS is a pore-based system in which beads moving through a pore cause a measurable increase in resistance which can be used to derive particle size, concentration, and mobility. During the course of this thesis several template TRPS aptasensors have been developed. TRPS was successfully used to confirm the successful coating of nano- and micro-scale beads with DNA aptamers by monitoring an increase in electrophoretic mobility when the negatively charged DNA is added to the surface. Following on from this, TRPS was used to monitor the interaction of aptamer tagged beads with thrombin protein enabling thrombin detection down to 1.4 nM and the comparison of several thrombin-aptamers with results comparable to previously published SPR data. Thrombin was postulated to shield the negative DNA, resulting in a decrease in mobility, and the magnitude of this charge shielding was found to depend upon the binding mechanism of the aptamer used. This effect is not thought to be specific to our system nor to thrombin, the principles outlined here may be applied to other RPS technologies, or by interchanging of the aptamer, different proteins. In later chapters, this method is expanded to include multiplexed detection of growth factors and a significant improvement in signal. vi Following on from this, the controlled aggregation of avidin coated beads in the presence of biotinylated-BSA was explored. Factors impacting upon this assay were discussed including magnetic separation, particle size and particle concentration, and different methods of data interpretation were presented. This aggregation study identified several key parameters in the use of TRPS in aggregation assays. Using the methods outlined by the study of aggregates, a dispersion assay was then designed in which the interaction of thrombin proteins with clusters of particles brought about the release of many small particles by the disruption of double stranded DNA linkages. This dispersion assay incorporated magnetic separation to simplify the read-out and relied on measuring particle concentration rather than mobility, enabling the use of additional pressure to increase speed and ease of use. Using this method, thrombin was able to be detected down to 100 fM, a significant advancement in TRPS aptasensors.

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Current research has developed a fully predictive model of an electrically heated common residential oven. This system was modeled using a fully explicit approach and, where applicable, considered natural convective correlations, various radiation networks, and conduction relations. Two oven configurations were modeled, a conventional (unmodified) residential oven and a modified design. By comparing the theoretical results obtained through modeling with experimental results, verification of the modeling assumptions and results has been achieved. This research has produced an analytical design tool for predictive modeling of time dependant surface temperatures, maximum expected temperatures, and the baking performance of various oven designs. Thus this software package can be used to predict the overall feasibility of an oven design prior to fabrication.

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