O óxido de índio dopado com estanho é um semicondutor degenerado de alta transparência no espectro visível e alta condutância elétrica. Por suas propriedades, ele é utilizado como eletrodo transparente em diversas aplicações. Algumas destas aplicações exigem que os filmes sejam depositados sobre substratos poliméricos, que degradam em temperaturas acima de 100 °C. Por este motivo, métodos de deposição que utilizam baixas temperaturas são necessários. O objetivo deste trabalho é o desenvolvimento de técnicas de deposição de filmes de óxido de índio dopado com estanho, em baixas temperaturas (< 100 °C), pelo método de magnetron sputtering de rádio fequência. Filmes foram obtidos sobre substratos de silício, vidro e policarbonato, e suas propriedades físicas, elétricas, ópticas, químicas e estruturais foram analisadas por perfilometria, elipsometria, curvas corrente-tensão, prova de quatro pontas, medidas de efeito Hall, difratometria de raios-X e espectrofotometria. Filmes depositados sobre silício e vidro tiveram resistividade elétrica mínima da ordem de 10^-4 Ohm.cm, enquanto a resistividade do filme obtido sobre policarbonato foi da ordem de 10^-3 Ohm.cm. A transmitância óptica média no espectro visível das amostras variou de 66 a 87 %. Do ponto de vista estrutural, as amostras tenderam a apresentar fase amorfa e cristalina, com orientação preferencial ao longo da direção [100]. De modo geral, as amostras obtidas de 75 a 125 W tiveram as melhores propriedades para serem utilizadas em aplicações que exijam eletrodos transparentes, considerando aspectos elétricos e ópticos. / Indium-tin oxide is a degenerate semiconductor that shows high transmittance in the visible region of the spectrum and high electrical conductance. Because of its properties, this material is used as transparent electrode in a wide variety of applications. Some of these applications demand the indium-tin oxide layer to be deposited over polymer substrates, which degrade at temperatures above 100 °C. Because of this degradation problem, deposition methods at low temperatures are needed. The purpose of this work is the development of low temperature (< 100 °C) indium-tin oxide deposition processes by radio frequency magnetron sputtering method. Thin films were deposited over silicon, glass and polycarbonate substrates, and their physical, electrical, optical, chemical and structural properties were analyzed by surface high step meter, ellipsometry, current-voltage curves, four-point probe analysis, Hall effect measurements, X-ray diffractometry and spectrophotometry. Films deposited over silicon and glass substrates showed minimal electrical resistivity in the order of 10^-4 Ohm.cm, while the resistivity of the film obtained over polycarbonate was in the order of 10^-3 Ohm.cm. The average transmittance in the visible spectrum varied over the range 66 to 87 %. According to the structural study, the films present both amorphous and crystalline phases, with crystallites showing preferential orientation along the [100] direction. In general, films deposited with power varying over the range 75 to 125 W showed the best results to be applied as transparent electrodes, considering electrical and optical aspects.

Dans le cadre de la fabrication de dispositifs pour l’électronique organique à grande échelle, les besoins en matériaux conducteurs stables à l’air libre, de coût réduit et compatibles avec les techniques d’impression sont croissants. Ces matériaux sont destinés à remplacer les couches métalliques déposés par des méthodes telles que la gravure ou l’évaporation sous vide. Les travaux présentés dans cette thèse ont pour objectif la mise au point d’une encre imprimable stable à l’air libre, composée de polyaniline dispersée en phase aqueuse. L’originalité de cette thèse est de décrire l’intégralité de ce processus, depuis la synthèse chimique de la charge, à partir du monomère jusqu’à l’intégration de l’encre conductrice dans une cellule solaire organique sous forme d’électrode imprimée, en passant par la formulation de l’encre. La première partie des travaux consacrés à la synthèse chimique de la charge a permis d’obtenir un matériau nano structuré, de taille et morphologie contrôlée, dispersable en phase aqueuse et conducteur. Cette dispersion a ensuite été formulée pour lui conférer des propriétés compatibles avec l’impression jet d’encre et lever des verrous critiques comme la granulométrie. La phase d’essai d’impression jet d’encre a permis de valider l’étape de formulation et d’optimiser la morphologie des gouttelettes éjectées. Les couches minces imprimées ont permis d’atteindre des résistances surfaciques inférieures à 1000 Ω/□. Finalement l’encre conductrice a pu être imprimée en tant qu’électrode supérieure dans des cellules solaires organiques. / Considering large-scale development and fabrication of organic electronic devices, needs for low cost conductive printable materials are growing. These materials are designed to replace thin metallic layers deposited via gravure or thermal evaporation. The objective of the work presented in this report is to obtain a conductive and inkjet printable aqueous stable dispersion of polyaniline. Originality of this PhD work is to describe all the steps from the chemical synthesis of polyaniline starting from the monomer, until the integration of the conductive ink in an organic solar cell as a conductive top electrode, through formulation of the ink to meet inkjet printing requirements. During the first part of work dedicated to chemical synthesis of PANI, we managed to produce a nanostructured and conductive material, with controlled size and morphology, which was dispersed in water. This aqueous dispersion was formulated to meet inkjet printing requirements and break technological locks such as particle size in the PANI dispersion. Formulation step was then validated during printing trials, which allowed optimising shape of ejected droplets. Printed PANI thin layers showed sheet resistance below 1000 Ω/□ after 20 printing passes. Finally, conductive ink was printed as a top electrode in fully solution–processed printed organic solar cell.

Problemas de resfriamento de circuitos, presentes nas indústrias de eletrônicos e miniaturizados, têm sido amplamente estudados com o propósito de desenvolver mecanismos capazes de reduzirem a taxa de falha nos equipamentos devido às altas temperaturas. O presente trabalho utiliza o método Design Construtal associado com algoritmos de otimização, busca exaustiva e algoritmo genético, para realizar o estudo numérico de corpos sólidos com geração de calor uniforme onde são inseridos caminhos altamente condutivos em forma de “Y”, “Y-Y”, duplo “Y-Y” e “T”. O objetivo principal das otimizações realizadas consiste em minimizar a resistência ao fluxo de calor, quando as áreas ocupadas pelos materiais de alta e baixa condutividades são mantidas constantes, variando-se os comprimentos e espessuras dos caminhos condutivos. Para a solução numérica da equação da difusão do calor com as condições de contorno estabelecidas em cada caso, foi utilizado o PDETool do software MatLab. A formulação para o caminho condutivo em forma de “Y” apresenta a construção de volumes elementares, mantendo a mesma condutividade térmica para todo o caminho condutivo. Na configuração em forma de duplo “Y – Y” foi utilizado o método de busca exaustiva associado ao algoritmo genético (GA). Nas simulações realizadas com o caminho condutivo em forma de “T”, a configuração apresenta combinações de condutividade térmica diferentes para a base e para a parte superior, enfatizando que a geometria depende das condições impostas pelo ambiente. Para o caso com um volume elementar, a configuração em forma de “Y” degenera-se gerando um caminho condutivo em forma de “U” e com dois volumes, a variação ocorre no comprimento dos ramos do caminho condutivo. Para a configuração com quatro volumes, a configuração ótima tem a forma de “X”. No caso do caminho em forma de “T”, a configuração que minimiza a máxima temperatura em excesso tem a forma de um “I”. Como previsto no princípio da ótima distribuição das imperfeições, a geometria ótima para os casos estudados é aquela que melhor distribui as imperfeições do sistema. / Problems that embody cooling of circuits that appears in electronics and miniaturized industries, have been widely studied to develop mechanisms capable of reducing the failure rate of the equipment due to high temperatures. The present work applies the Constructal Design method associated with optimization algorithms, exhaustive search and genetic algorithm, to perform the numerical study of solid bodies with uniform heat generation in which are inserted high-conducting pathways with “Y”, “Y–Y”, double “Y–Y” and “T” shapes. The main goal of the performed optimizations consists in minimizing the resistance to the heat flux when the occupied areas of high and low conductivity materials are maintained constant, varying the lengths and thickness of conductive paths. For the numerical solution of the heat diffusion equation with the boundary conditions established in each case, it was used the PDETool from MatLab software. The formulation for the conductive pathway with "Y" shape presents the construction of elementary volumes, maintaining the same thermal conductivity across the entire conductive pathway. In the configuration in double “Y–Y” form it was used exhaustive search method associated with genetic algorithm (GA). In the simulations performed with the T-shaped conductive pathway, the configuration provides combinations of different thermal conductivity for the base and the top, emphasizing that the geometry depends on the conditions imposed by the environment. For the case with one elementary volume, the Y-shaped configuration degenerates producing a conductive pathway with U-shape; and with two volumes, the variation occurs in the length of branches of the conductive pathway. For the configuration with four volumes, the optimum configuration has the form of “X”. In the case of T-shaped pathway, the configuration that minimizes the maximal excess of temperature is I-shaped. As predicted by the principle of optimal distribution of the imperfections, the optimal geometry for the cases studied is the one that promotes the best distribution of the imperfections of the system.

Electroactive textile fibers are key components in smart and interactive textile applications. In previous research on textile base conductive fibers, viscose fibers were coated with poly (3,4-ethylenedioxythiophne) (PEDOT) using oxidative chemical vapor deposition (oCVD) technique[1]. Ferric chloride was used as oxidant and reaction conditions were optimized at which better electrical as well as mechanical properties of conductive viscose fibers could be achieved. In this thesis work, effect of new parameters such as pretreatment of viscose fibers with solvents, drying of oxidant treated viscose fibers at different time and temperature and comparison of two different oxidants have been tried. One new and important oxidant, ferric (III) p-toluene sulfonate or ferric (III) tosylate, used to prepare PEDOT coated viscose fibers and then compared with PEDOT coated viscose fibers prepared using oxidant ferric (III) chloride. Viscose fibers have been treated with two well know solvents, acetone and ethyl acetate before soaking in oxidant solution. Oxidant enriched fibers dried at different temperature for variable time prior to polymerization step. Knitted structures of conductive viscose fibers have been prepared. Hand washing of PEDOT coated viscose fibers with tap water and machine washing of knitted structures according to the international standard ISO EN-6330 have been performed and washing effects were investigated. Effects of all of the above mentioned variables on electromechanical properties of PEDOT coated viscose fibers were studied by using tensile testing, TGA analysis, FTIR spectra and conductivity measurements. Stretch sensing properties of knitted structures; before and after washing, were determined on cyclic tester. The purpose of this study is to enhance the properties of PEDOT-coated viscose fibers by controlling different parameters and to evaluate their usage as stretch sensors as well as to check the washability of PEDOT coated viscose fibers and knitted structures. Better electromechanical properties were achieved on new parameters and PEDOT coated viscose fibers were successfully utilized as stretch sensors. PEDOT coated viscose fibers could have potential to apply in areas such as, military textiles, medical textiles and sensors. / Program: Master programme in Textile Technology

During this project it was investigated how the newly developed piezoelectric PVDF bicomponent fibre behaved when integrated in different weave constructions. The possibility to integrate conductive yarns as outer electrode was studied in order to see if it was possible to create a fully textile piezoelectric sensors. The piezoelectric properties of the bicomponent fibre is given by the sheath material, which is a polymeric material known as poly(vinylidene fluoride) (PVDF). Today only piezoelectric film made by PVDF is commercially available, but with a flexible PVDF bicomponent fibre it improves the possibility to integrate piezoelectric material into a textile construction. In this study the PVDF bicomponent fibre was integrated in the warp direction into weave constructions, such as plain weave, twill and weft rib. All the woven bands included 60 PVDF bicomponent yarns, with 24 filaments in each bundle and the average width of the bands produced was 30 mm. Different conductive materials and fibres, acting as outer electrode, were coated or integrated together with the PVDF fibre and the behaviour of the PVDF fibres was analysed. All the woven samples went through corona poling with a voltage of 7 kV in 70 ⁰C for 3 min. The weave construction that gave highest piezoelectric output signal was twill with weft that has low tex. The twill construction gave a range amplitude of 1.5- 3.3 V when subjected to a dynamic strain of about 0.25% at 4 Hz. It was shown that different conductive materials influenced the PVDF fibre in different ways, due to the resistance of the material. It was also shown that it was possible to integrate piezoelectric bicomponent fibre into a textile construction and that a fully textile piezoelectric sensor could be produced by using conductive yarns as outer electrode. / Program: Masterutbildning i textilteknik,

Les effets de la force magnétique orthogonale (MF) sur le processus d'électropolymérisation de l'aniline dans une solution d’acide chlorhydrique ont été étudiés.La voltammétrie cyclique (CV), la chronoampérométrie et la spectroscopie d'impédance électrochimique (EIS), ont été utilisées pour examiner le processus de transfert de masse et le processus de réaction électrochimique. Différentes techniques, telles que la microscopie électronique à balayage (MEB), la microscopie à force atomique (AFM) et la diffraction à rayons X (XRD) ont été utilisées pour caractériser les revêtements préparés.Les résultats montrent que la vitesse de dépôt augmente avec la force magnétique et la concentration du monomère d’aniline en raison de la convection magnétique et les propriétés magnétiques du radical.L’imagerie MEB et l'analyse topologique ont révélé que, sous MF les films sont essentiellement composés de gonflement des nanofibres et des ilots des polymères qui sont bien répartis sur la surface. Les études de diffraction à rayons X révèlent une amélioration de la cristallinité des couches, sans orientations préférentielles.Mots clés: polymère, polyaniline, aniline, champ magnétique, électropolymerisation, impédance électrochimique, DFT, susceptibilité magnétique. / The effects of static orthogonal magnetic force (MF) on the electropolymerization process of aniline from hydrochloric bath have been investigated. Cyclic voltammetry (CV), Chronoamperometry and electrochemical impedance spectroscopy (EIS) techniques were used to examine the mass transfer process and electrochemical reaction process. Different techniques, such as Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and X-ray Diffraction (XRD) were employed to characterize the prepared coatings. The results show that deposit rate increased with increasing MF and aniline monomer concentration due to the magneto-convection involving the mass transport and radical magnetic properties. SEM imagery and topological analysis revealed that under MF the films are essentially composed of swelling of the nanofibers and ilots of polymers that are well distributed on the surface. The XRD studies reveal an enhancement of the crystallinity of the coatings without any preferential orientations.Keywords: Polymers, Polyaniline, aniline, Magnetic fiels, Electropolymerization, electrochemical impedance, DFT, magnetic susceptibility .

Nesse trabalho é apresentado o estudo de redes neurais artificiais (RNAs) como sistemas de aprendizado, simulação e otimização de processos de deposição de filmes finos poliméricos. Duas técnicas de deposição comumente utilizadas para a fabricação de dispositivos eletrônicos e sensores poliméricos foram escolhidas: i) spin coating ou centrifugação e ii) automontagem. Na primeira técnica, a espessura final dos filmes finos obtidos foi a característica avaliada em função da velocidade de rotação, do tempo de rotação e da concentração da solução polimérica. Como material de deposição, utilizou-se a poli(o-metoxianilina) (POMA). Com a segunda técnica analisou-se a influência sobre a espessura, sobre a condutância elétrica e sobre o espectro de absorção, do número de bicamadas, do tempo de exposição dos filmes a uma solução dopante de ácido clorídrico (HCl) e do pH das mesmas. Os poliíons utilizados nessa técnica foram a polianilina (PAni) e o poli(vinil sulfato de sódio) (PVS). Os filmes obtidos pela segunda técnica de deposição constituem uma classe de sensores capazes de detectar e quantificar concentrações baixas de HCl diluído em água. Os treinamentos e simulações com redes neurais artificiais foram realizados apenas para a espessura dos filmes de POMA e a absorção dos filmes de PAni/PVS. Foram construídas redes neurais artificiais do tipo multilayer perceptron (MLP) utilizando o software MATLAB e o componente Neural Networks Toolbox. A reprodutibilidade e o número de neurônios contidos na camada intermediária foram avaliados. Os resultados mostram que as redes neurais artificiais treinadas fornecem boas respostas simuladas interpolando e extrapolando os valores experimentais utilizados. Como conclusão mostra-se que é possível a utilização dessa ferramenta para auxiliar a engenharia de processos, as técnicas e análises de deposições de filmes finos poliméricos. / In this work it is shown a study of artificial neural networks used as learning and simulating systems to optimize polymeric thin films deposition processes. Two common layer deposition techniques to fabricate polymeric electronic devices and polymeric sensors were chosen: i) spin coating and ii) self-assembly. In the first technique the final thickness of obtained thin films was the analyzed characteristic as a function of spin speed, spin time and solution concentration. For the deposited layers we used poly(o-methoxyaniline) (POMA). In the second technique we analyzed the influence of the number of bilayers, the pH of deposition solutions and the dipping time in the final thickness, electrical resistance and UV-Vis absorption spectra. As polyions, we used polyaniline (PAni) and poly(vinyl sodium sulfate) (PVS). These films could be used as a sensor to detect low concentrations of HCl diluted in water. After obtaining the experimental data we constructed artificial neural networks using multilayer perceptrons (MLP) architecture with MATLAB and its component called Neural Networks Toolbox. The number of neurons in the hidden layer and the reproducibility were analyzed. The results show that the trained artificial neural networks used in this work provide good simulation responses interpolating and extrapolating the experimental data. As a conclusion we show that it is possible to utilize this tool to aid the process engineering and the polymeric thin film deposition techniques and analysis

Organic electronics is the study of organic materials with electronic functionality and the applications of such materials. In the 1970s, the discovery that polymers can be made electrically conductive led to an explosion within this field which has continued to grow year by year. One of the attractive features of organic electronic materials is their inherent mechanical flexibility, which has led to the development of numerous flexible electronics technologies such as organic light emitting diodes and solar cells on flexible substrates. The possibility to produce electronics on flexible substrates like plastic or paper has also had a large impact on the field of printed, electronics where inks with electronic functionality are used for large area fabrication of electronic devices using classical printing methods, such as screen printing, inkjet printing and flexography. Recently, there has been a growing interest in the use of cellulose in organic and printed electronics, not only as a paper substrate but also as a component in composite materials where the cellulose provides mechanical strength and favorable 3D-microstructures. Nanofibrillated cellulose is composed of cellulose fibers with high aspect-ratio and diameters in the nanometer range. Due to its remarkable mechanical strength, large area-to-volume ratio, optical transparency and solution processability it has been widely used as a scaffold or binder for electronically active materials in applications such as batteries, supercapacitors and optoelectronics. The focus of this thesis is on flexible devices based on conductive polymers and can be divided into two parts: (1) Composite materials of nanofibrillated cellulose and the conductive polymer PEDOT:PSS and (2) patterning of vapor phase polymerized conductive polymers. In the first part, it is demonstrated how the combination of cellulose and conductive polymers can be used to make electronic materials of various form factors and functionality. Thick, freestanding and flexible “papers” are used to realize electrochemical devices such as transistors and supercapacitors while lightweight, porous and elastic aerogels are used for sensor applications. The second focus of the thesis is on a novel method of patterning conductive polymers produced by vapor phase polymerization using UV-light. This method is used to realize flexible electrochromic smart windows with high-resolution images and tunable optical contrast.

Acromegalia à uma doenÃa endÃcrina rara. Poucos estudos avaliaram sua associaÃÃo com deficiÃncia auditiva (DA) ou distÃrbios de conduÃÃo do impulso neural auditivo.Osresultados sÃo conflitantes. O objetivo à avaliar a transmissÃo auditiva central e perifÃrica em pacientes com acromegalia. AlÃm disso, avaliar a prevalÃncia e caracterÃsticas da DA em pacientes com acromegalia. Foi feito um estudo transversal com 36 pacientes com acromegalia de um ambulatÃrio especializado em Fortaleza-CearÃ. Foram excluÃdos pacientes com otoscopia anormal ou com histÃria familiar de deficiÃncia auditiva, uso de ototÃxicos ou exposiÃÃo a ruÃdo ocupacional. Inicialmente, o grupo foi avaliado por meio de audiometria tonal limiar. Considerou-se deficiÃncia auditiva (DA) quando a mÃdia dos tons puros foi > 25DbNA para baixas freqÃÃncias (250, 500, 1000 e 2000 Hz) ou altas freqÃÃncias (3000, 4000, 6000 e 8000 Hz).O grupo foi dividido em: acromegalia com DA (Acro DA) e sem DA (Acro NDA) e comparados quanto aos nÃveis hormonais e parÃmetros metabÃlicos. Posteriormente, este grupo de pacientes com acromegalia foi dividido em 2 subgrupos: com (n=16) e sem (n=20) diabetes ou intolerÃncia à glicose de jejum (DM/IGJ). Os resultados foram comparados entre os subgrupos e grupo controle (n=20) quantos aos parÃmetros dos potenciais evocados auditivos de tronco encefÃlico (PEATE). Para avaliar a normalidade da distribuiÃÃo foi utilizado o teste de Kolmogorov-Smirnov quando necessÃrio. Utilizou-se os testes qui-quadrado, t de Student e coeficiente de correlaÃÃo de Pearson. O nÃvel de significÃncia estatÃstica escolhido foi p<0.05 (statistical package for social sciences-SPSS 12.0). Dos 36 pacientes estudados, 14 (38,9%) mostraram DA sensorioneural (Acro DA), sendo em 9 casos bilateral e 5 unilateral. Nenhum apresentou DA mista ou condutiva. A prevalÃncia de DM/IGJ foi similar entre os grupos. As frequÃncias de 250, 3000, 4000, 6000 e 8000 Hz foram as mais afetadas e com padrÃo similar em ambos os lados.O grupo com acromegalia apresentou latÃncia da onda I em orelha direita aumentada em comparaÃÃo ao grupo controle (p=0,007), sem diferenÃa quanto aos intervalos interpicos em nenhum dos lados. Esse padrÃo foi o mesmo quando se comparou o subgrupo com DM/IGJ com o controle.TambÃm houve aumento da latÃncia da onda I na orelha direita em relaÃÃo à orelha esquerda no grupo com acromegalia. Em conclusÃo, mostrou-se uma elevada prevalÃncia de DA sensorioneural em pacientes com acromegalia.No entanto, nÃo se observou relaÃÃo dessa deficiÃncia com caracterÃsticas clÃnicas e metabÃlicas da doenÃa.Pacientes com acromegalia associada DM/IGJ mostraram um retardo no impulso neural no nervo auditivo unilateralmente à direita, evidenciando um efeito neuropÃtico nÃo homogÃneo dos distÃrbios do metabolismo dos carboidratos sobre o nervo auditivo. / Acromegaly is a rare endocrine disease. Few studies have evaluated its association with hearing loss (HL) or disturbance in conduction of the auditory neural impulse. The results are conflicting. The aim is to evaluate central and peripheral auditory transmission in acromegalic patients. Besides, to evaluate the prevalence and characteristics of HL in patients with acromegaly. A cross-sectional study was carried out on 36 patients with acromegaly in a specialized ambulatory in Fortaleza-CearÃ. Patients with abnormal otoscopy, family history of hearing loss, use of ototoxic drugs or occupational noise exposure were excluded. Initially, the group was evaluated by pure tone audiometry. HL was considered when pure tone average was > 25 DBHL for low frequencies (250, 500, 1000 e 2000 Hz) or high frequencies (3000, 4000, 6000 e 8000 Hz). The whole group was divided in: acromegaly with HL (Acro HL) and without HL (AcroNHL) and compared in regards to hormonal levels and metabolic parameters. Additionally that group of patients with acromegaly was divided into 2 subgroups: with (n=16) and without (n=20) diabetes mellitus/impaired glucose tolerance (DM/IGT). The results were compared among these subgroups and a control group (n=20) regarding the brainstem auditory evoked potentials (BAEP) parameters.Kolmogorov-Smirnov test was used to evaluate the normality of distribution when necessary. Qui-quadrado, Student t test and Pearson correlation coefficient were carried out. The level of statistical significance chosen was at p<0.05 (statistical package for social sciences-SPSS 12.0). Among 36 patients evaluated, 14 (38,9%) showed sensorioneural HL (Acro HL), being 9 bilateral and 5 unilateral cases. No one had mixed or conductive HL. The prevalence of diabetes/impaired glucose tolerance was similar between the groups. The frequencies 250, 3000, 4000, 6000 and 8000 Hz were the most affected and with a similar pattern in both ears. The group with acromegaly showed a prolonged peak I latency in the right ear in comparison to the control group (p=0,007), with no difference regarding the interpeak intervals in any sides. This pattern was the same when comparing the DM/IGT subgroup to controls. Also, we found a prolonged peak I latency in the right ear in relation to the left ear in the group with acromegaly.In conclusion, a high prevalence of sensorineural HL was shown in patients with acromegaly. Nevertheless, no correlation was observed between this dysfunction and clinical or metabolic characteristics of the disease. Patients with acromegaly associated with DM/IGT showed a delayed neural impulse in the auditory nerve unilaterally in the right side, evidencing a non-homogenous neuropathic effect of the carbohydrate metabolism disturbances on the auditory nerve.

Os principais objetivos deste trabalho são estudar e caracterizar as perdas em acoplamentos magnéticos a ímãs permanentes, quando da existência de uma barreira de material condutor entre seus rotores. Tais perdas são originadas da circulação de correntes parasitas de Foucault na barreira e implicam um torque resistivo ao torque transmitido pelo acoplamento, diminuindo, dessa maneira, a eficácia de sua transmissão. Com este estudo pretendeu-se investigar também a influência desse efeito resistivo na curva característica do acoplamento, ou seja, na curva torque em função do deslocamento angular entre os rotores. A determinação dessa influência da placa condutora no comportamento do acoplamento magnético é de suma importância, uma vez que permite seu correto dimensionamento em aplicações como bombas seladas e agitadores. Para a determinação da influência da barreira, recorreu-se a uma abordagem analítica para o cálculo das perdas geradas pelas correntes parasitas, que são induzidas na placa condutora. Desta forma, foi possível obter o torque resistivo em função dos parâmetros construtivos do acoplamento e da velocidade de rotação. A validação da metodologia empregada será feita pela comparação dos resultados teóricos com os experimentais, através de ensaios num protótipo já construído. / The main objectives of this work are to study and to determine losses in permanent magnet couplings in the presence of a conductive barrier between its rotors. These losses are originated from eddy currents that circulate in the barrier and entail a resistive torque to the torque that is transmitted by the coupling and therefore, reduces the efficiency of its transmission. With this study, it was also intended to investigate such resistive effect influence in the coupling characteristic curve, i.e. in the torque versus angular shift between rotors curve. The determination of the conductive barrier influence on the magnetic coupling behavior is of major importance, since it allows the correct designing in applications as sealed pumps and magnetic stirrers. In order to determine the barrier influence, an analytical approach was used in order to calculate the losses generated by the eddy current circulation, which are induced in the conductive wall. As a result, it was possible to obtain the resistive torque as a function of the magnet coupling geometrical parameters and angular speed. The validation of the employed methodology will be made comparing the theoretical results with the experimental ones, obtained from tests in the existing prototype.