Acoustic micro-sensors have already been applied in mass sensing including surface acoustic wave (SAW), flexural plate wave (FPW), thickness shear mode (TSM) and shear horizontal acoustic plate mode (SH-APM). The FPW micro-sensor is very suitable for liquid-sensing and bio-sensing applications due to the high mass-sensitivity and low phase-velocity in liquid. However, the conventional FPW micro-sensors presented a high insertion-loss (IL) and a low signal-to-noise ratio so it is difficult to combine with IC into a micro-system. To overcome these drawbacks, this study combine the Microelectromechanical System (MEMS) technology and the high C-axis orientation ZnO piezoelectric thin-film to develop a low insertion loss, low operation frequency, and high electromechanical coupling coefficient FPW device. In this study, a high C-axis orientation ZnO piezoelectric thin-film with a 20944A.U. X-Ray diffraction intensity at 34.200 degree and a 0.573 degree full width at half maximum (FWHM) was deposited by a commercial magnetic radio-frequency (RF) sputter system. The total processes of the FPW micro-sensor included five photolithography and seven thin-film depositions. In this study a low operation frequency (0.1MHz), low insertion loss (11dB to 14dB) and high electromechanical coupling coefficient (11%) FPW sensor was developed and fabricated.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-03-03T13:09:08Z No. of bitstreams: 1 bernardolinodeoliveira.pdf: 2207336 bytes, checksum: 11a9525b863f45bfd41eb505e9f25791 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-03-06T20:07:32Z (GMT) No. of bitstreams: 1 bernardolinodeoliveira.pdf: 2207336 bytes, checksum: 11a9525b863f45bfd41eb505e9f25791 (MD5) / Made available in DSpace on 2017-03-06T20:07:32Z (GMT). No. of bitstreams: 1 bernardolinodeoliveira.pdf: 2207336 bytes, checksum: 11a9525b863f45bfd41eb505e9f25791 (MD5) Previous issue date: 2011-01-17 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Doenças cardiovasculares estão relacionadas com um alto índice de mortalidade no mundo. Tendo isto em vista, a modelagem computacional cardíaca tornou-se uma ferramenta importante no suporte ao teste de novas drogas e no desenvolvimento de novos equipamentos e técnicas de diagnóstico. O objetivo deste trabalho é o estudo e desenvolvimento de novos modelos para o acoplamento eletromecânico de células e tecidos cardíacos, em especial do ventrículo esquerdo, que é a principal estrutura responsável pelo bombeamento do sangue para o corpo. Este trabalho foi dividido em duas principais etapas: 1) Desenvolvimento de um novo modelo para a eletromecânica dos cardiomiócitos do ventrículo esquerdo humano, a partir do acoplamento de dois modelos preexistentes, um para a eletrofisiologia e outro para a geração de força ativa nos miofilamentos. No desenvolvimento do modelo, técnicas de otimização como algoritmos genéticos foram utilizadas para o ajuste de parâmetros de forma que o modelo reproduzisse os escassos dados experimentais para humanos encontrados na literatura. 2) A incorporação deste modelo em simulações de maior escala, em nível de tecido. Tratamos neste trabalho os problemas numéricos e metodológicos que esta incorporação acarreta. Além disso, analisamos a influência da deformação mecânica em características eletrofisiológicas, como a forma da onda de eletrogramas ventriculares. / Cardiac diseases are associated with high mortality rates around the globe. With this in mind, cardiac computational modeling has become an important tool to support the test of new drugs, the development of new devices and of diagnostic techniques. The objective of this work is the study and development of new models for the electromechanical coupling of heart cells and tissues, in particular the left ventricle, which is the main structure responsible for pumping blood to the body. This work can be divided in two main steps: 1) The development of a new model for the electromechanics of human left ventricle cardiac myocytes, based on the coupling of two existing models, one for the electrophysiology and another for the myofilament active force generation. On the development of this model optimization techniques like genetic algorithms where used for the parameter adjustment to reproduce the few experimental data available in the literature. 2) This model was embedded in larger scale electromechanical simulations, i.e. tissue level. This work treats the numerical and methodological problems that this coupling brings. Furthermore, we analyze the influence of the mechanical deformation in important eletrophysiological features, such as the waveform of ventricular electrograms.

Submitted by Geandra Rodrigues (geandrar@gmail.com) on 2018-03-27T15:52:15Z No. of bitstreams: 1 joaogabrielrochasilva.pdf: 4504745 bytes, checksum: 5d371d913693d1bf3a9425d887ab2ed1 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-03-27T17:49:33Z (GMT) No. of bitstreams: 1 joaogabrielrochasilva.pdf: 4504745 bytes, checksum: 5d371d913693d1bf3a9425d887ab2ed1 (MD5) / Made available in DSpace on 2018-03-27T17:49:33Z (GMT). No. of bitstreams: 1 joaogabrielrochasilva.pdf: 4504745 bytes, checksum: 5d371d913693d1bf3a9425d887ab2ed1 (MD5) Previous issue date: 2018-02-23 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A simulação da atividade eletromecânica do coração é uma ferramenta relevante para a interpretação e estudos de medidas fisiológicas e diversos fenômenos cardíacos. Entretanto, modelos computacionais para este propósito podem ser computacionalmente custosos. Assim, são propostos neste trabalho três modelos simplificados, a nível celular, que foram capazes de reproduzir de forma quantitativa o fenômeno da contração de miócitos cardíacos. Para obtenção destes modelos um ajuste de parâmetros foi realizado via algoritmos genéticos. Os modelos propostos com parâmetros ajustados apresentaram resultados satisfatórios para reprodução da força ativa do coração com a vantagem de serem baseados em apenas duas equações diferenciais ordinárias. Além disso, o modelo final foi validado utilizando simulações envolvendo extra-sístoles, sendo capaz de reproduzir o fenômeno de alternância na força ativa. / The simulation of the heart electromechanical activity is a relevant tool for the interpretation and studies of physiological measures and various cardiac phenomena. However, computational models for this purpose may be computationally costly. Thus, three simplified models which were able to quantitatively reproduce the phenomenon of cardiac myocyte contraction were proposed in this work. At the cellular level, they were able to quantitatively reproduce the phenomenon of cardiac myocyte contraction. A parameter adjustment via genetic algorithm was performed to obtain these models. The proposed models with adjusted parameters presented satisfactory results for the reproduction of the active force of the heart with the advantage of being based on only two ordinary differential equations. In addition, the final model was validated using simulations involving extra-systoles, being able to reproduce the phenomenon of alternation in the active stress.

Cette thèse est dédiée à l'analyse mathématique et la simulation numérique des équations intervenant dans la modélisation de l’électrophysiologie cardiaque. D'abord, nous donnons une justification mathématique rigoureuse du processus d’homogénéisation périodique à l’aide de la méthode d'éclatement périodique. Nous considérons des conductivités électriques tensorielles qui dépendent de l’espace et des modèles ioniques non linéaires physiologiques et phénoménologiques. Nous montrons l'existence et l'unicité d’une solution du modèle microscopique en utilisant une approche constructive de Faedo- Galerkin suivie par un argument de compacité dans L2. Ensuite, nous montrons la convergence de la suite de solutions du problème microscopique vers la solution du problème macroscopique. À cause des termes non linéaires sur la variété oscillante, nous utilisons l’opérateur d’éclatement sur la surface et un argument de compacité de type Kolmogorov pour les modèles phénoménologiques et de type Minty pour les modèles physiologiques. En outre, nous considérons le modèle monodomaine couplé au modèle physiologique de Beeler-Reuter. Nous proposons un schéma volumes finis et nous analysons sa convergence. D'abord, nous dérivons la formulation variationnelle discrète correspondante et nous montrons l'existence et l'unicité de sa solution. Par compacité, nous obtenons la convergence de la solution discrète. Comme le schéma TPFA (two point flux approximation) est inefficace pour approcher les flux diffusifs avec des tenseurs anisotropes, nous proposons et analysons, ensuite, un schéma combiné non-linéaire qui préserve le principe de maximum. Ce schéma est basé sur l’utilisation d’un flux numérique de Godunov pour le terme de diffusion assurant que les solutions discrètes soient bornées sans restriction sur le maillage du domaine spatial ni sur les coefficients de transmissibilité. Enfin, dans la perspective d'étudier la solvabilité des modèles électromécaniques couplés avec des modèles ioniques physiologiques, nous considérons un modèle avec une description linéarisée de la réponse élastique passive du tissu cardiaque, une linéarisation de la contrainte d'incompressibilité et une approximation tronquée des diffusivités non linéaires intervenant dans les équations du modèle bidomaine. La preuve utilise des approximations par des systèmes non-dégénérés et la méthode Faedo-Galerkin suivie par un argument de compacité. / This thesis is concerned with the mathematical analysis and numerical simulation of cardiac electrophysiology models. We use the unfolding method of homogenization to rigorously derive the macroscopic bidomain equations. We consider tensorial and space dependent conductivities and physiological and simplified ionic models. Using the Faedo-Galerkin approach followed by compactness, we prove the existence and uniqueness of solution to the microscopic bidomain model. The convergence of a sequence of solutions of the microscopic model to the solution of the macroscopic model is then obtained. Due to the nonlinear terms on the oscillating manifold, the boundary unfolding operator is used as well as a Kolmogorov compactness argument for the simplified models and a Minty type argument for the physiological models. Furthermore, we consider the monodomain model coupled to Beeler- Reuter's ionic model. We propose a finite volume scheme and analyze its convergence. First, we show existence and uniqueness of its solution. By compactness, the convergence of the discrete solution is obtained. Since the two-point flux approximation (TPFA) scheme is inefficient in approximating anisotropic diffusion fluxes, we propose and analyze a nonlinear combined scheme that preserves the maximum principle. In this scheme, a Godunov approximation to the diffusion term ensures that the solutions are bounded without any restriction on the transmissibilities or on the mesh. Finally, in view of adressing the solvability of cardiac electromechanics coupled to physiological ionic models, we considered a model with a linearized description of the passive elastic response of cardiac tissue, a linearized incompressibility constraint, and a truncated approximation of the nonlinear diffusivities appearing in the bidomain equations. The existence proof is done using nondegenerate approximation systems and the Faedo-Galerkin method followed by a compactness argument.

Les matériaux piézoélectriques et ferroélectriques présentent un comportementélectromécanique couplé. Cette particularité leur a permis d’être utilisés dans de nombreusesapplications telles que les applications de capteur, actionneur, transformateur et récupérateurd’énergie. En outre, en raison de leur comportement non linéaire et dissipatif, les matériauxferroélectriques sont de plus en plus utilisés dans le domaine de l’électronique en tant quecapacité accordable, mémoire non volatile, oscillateur et filtre. La performance et la fiabilitéde ces systèmes dépendent directement des propriétés ferroélectriques et piézoélectriques dumatériau, qui nécessite par conséquent d’être caractérisé. Les propriétés piézoélectriques,ferroélectriques, ferroélastiques et diélectriques des matériaux ferroélectriques ont été le sujetde nombreuses études. Pourtant, les conditions d’essai restent difficiles à maîtriser car lespropriétés thermiques, mécaniques et électriques de ces matériaux sont fortement couplées.Dans cette thèse, un dispositif de mesure de champ de déformation a été conçu pourcaractériser le comportement piézoélectrique et ferroélectrique des céramiquesferroélectriques. Ce dispositif utilise un banc optique ainsi qu’un algorithme de Corrélationd’Images Numériques (CIN) 2D appelé CorreliRT3. Cet algorithme est basé sur une approcheglobale et réduit les erreurs de mesure de déplacement en s’appuyant sur les équationsd’équilibre de la mécanique des solides. Grâce au banc de caractérisation par CIN, il estmontré que les déformations piézoélectriques et ferroélectriques peuvent être mesurées avecune incertitude d’environ 10-5. Cette incertitude est atteinte aussi bien pour des sollicitationssimples que couplées (champ électrique et/ou contrainte mécanique). Il est aussi montré quele banc expérimental permet de vérifier les conditions d’essai en caractérisant l’hétérogénéitédes déformations lors d’un essai matériau.Dans les deux derniers chapitres, un matériau ferroélectrique est caractérisé souschamp électrique et sous contrainte mécanique. Le comportement du matériau est présenté etdiscuté dans les différentes configurations de chargement. Les propriétés matériau, telles queles coefficients piézoélectriques (d33, d31), sont extraites et étudiées en fonction du champélectrique et de la contrainte. Les résultats montrent que la CIN est capable de mesurer etcaractériser le comportement et les propriétés des matériaux ferroélectriques etpiézoélectriques. L’avantage de la CIN étant que, contrairement aux méthodes de mesureclassiques, celle-ci ne perturbe pas les conditions d’essai (mesure sans contact) et permette dedétecter la présence d’erreurs systématiques. / Piezoelectric and ferroelectric materials exhibit a coupled electromechanicalbehaviour. This property allows a use in various kinds of applications such as sensors,actuators, harvesting devices or converters. In addition, due to their non-linear and dissipativebehaviour, ferroelectric materials are increasingly used in electronic applications such astunable capacitors, non-volatile memory, oscillators and filters. The performance andreliability of such devices depend on the material electromechanical properties, whichconsequently need to be characterised. In the past decades, such characterisation was largelydeveloped and the piezoelectric, ferroelectric, ferroelastic and dielectric properties offerroelectrics were the subject of numerous studies. Yet the test conditions are difficult tocontrol due to the strong interplay between thermal, mechanical and dielectric properties.In this work, a full-field measurement apparatus has been designed to characterise thepiezoelectric and ferroelectric strain behaviour of ferroelectric ceramics. This apparatus usesan optical setup and a 2D Digital Image Correlation (DIC) algorithm named CorreliRT3. Thealgorithm is based on a global approach and reduces the displacement field errors using thebalance equations of solid mechanics. It is shown that piezoelectric and ferroelectric strainscan be measured with an uncertainty around 10-5 by using the developed setup. Thisuncertainty is reached under uncoupled or coupled loading (electric field and/or stress). It isalso shown that the experimental setup can control the test conditions by characterising thestrain heterogeneity during the test.In the two last chapters, a ferroelectric material is characterised under electric field andstress. The material behaviour is presented and discussed in the different loadingconfigurations. Material properties, such as the longitudinal and transverse piezoelectriccoefficients (d33, d31) are extracted and analysed as a function of the electric field and stress.The results show that the DIC technique is able to measure and characterise the behaviour andthe properties of ferroelectric and piezoelectric materials. The main benefits of this techniqueis that, contrary to classical measurement techniques, the measurement does not alter the testconditions. Moreover, DIC is able to detect test anomalies such as strain heterogeneities

La thèse porte de manière générale sur les polymères électrostrictifs qui peuvent être utilisés soit comme actionneurs électromécaniques souples, soit comme capteurs ou récupérateurs d’énergie. Le premier chapitre est une introduction générale aux systèmes couplés électromécaniques. Le choix des matériaux est exposé et porte sur les élastomères diélectriques et les polyuréthanes (PU) chargés par des nanoparticules conductrices de noir de carbone (CB). Le second chapitre porte sur la réalisation des films. Des particules de CB sous forme de micelles préformées et une technique « solution-cast » sont employées dans cette optique. Ce procédé permet une bonne dispersion des charges. Une amélioration de la déformation d’un facteur 1,6 est obtenue par introduction de particules de CB à 0.89 vol%. Le troisième chapitre présente la modélisation de phénomènes comme la saturation de la polarisation qui implique directement une saturation de la déformation. En modélisant la polarisation comme une fonction non-linéaire dépendant de deux variables (la permittivité bas niveau et un champ de saturation), on décrit ainsi correctement plusieurs phénomènes qui ne peuvent être interprétés par une approche linéaire et homogène. Les simulations effectuées montrent une bonne corrélation avec les expérimentations menées. Le quatrième chapitre propose une comparaison entre les films PU purs et chargés. Cette analyse porte non seulement sur des mesures mécaniques et électriques mais également en XRD ou en DSC afin de détecter le niveau de cristallisation. Une dispersion importante a ainsi été observée visuellement. Des déformations de l’ordre de 50 % ont ainsi été obtenues. Le cinquième chapitre porte sur l’effet lié à l’injection de charges électriques par bombardement électronique (HEBI), sur la déformation électrostrictive. Une telle approche permet ainsi un gain d’un facteur de l’ordre de 2 sur la déformation et semble réduire les pertes de façon très conséquente. / In a general manner, the present thesis focuses on electrostrictive polymers which can be used either as flexible electromechanical actuators or as sensors or energy harvesters. Chapter 1 is a general introduction to electro-mechanical coupled systems. The choice of the materials is described and focuses on dielectric elastomers, polyurethane (PU) with conductive carbon black (CB) nano-particle fillers. Chapter 2 focuses on the film synthesis. CB nano-particles in the form of micelles and solution cast method were employed to provide good filler dispersion. The strain enhancement of a factor of 1.6 was obtained by 0.89 vol% CB doping. Chapter 3 exposes the modeling of electrostrictive actuation and in particular the saturation of the polarization. By modeling the polarization as a nonlinear function depending on two variables (low-level permittivity and saturation field), it is therefore possible to describe several phenomena that cannot be explained by a classical linear and homogeneous approach. Simulations performed using such an approach show a good agreement with experimental results. Chapter 4 presents the comparison between pure PU and composite films. It includes mechanical/electrical characterization as well as XRD or DSC measurements to detect the crystallization level. High dispersion level was visually confirmed. Strains of the order of 50 % were reached. Chapter 5 deals with the effect of electric charge injection by homogeneous electron beam irradiation (HEBI) on the electrostrictive strain. This technique therefore permits a gain of 2 on the obtained strain and seems to significantly reduce the losses in the material as well.

Wind power is an established mean of clean energy production and the modern horizontal axis wind turbine has become a common sight. The need for maintenance is high and future wind turbines may need to be improved to enable more remote and offshore locations. Vertical axis wind turbines have possible benefits, such as higher reliability, less noise and lower centre of gravity. This thesis focuses on electromechanical interaction in the straight bladed Darrieus rotor (H-rotor) concept studied at Uppsala University. One of the challenges with vertical axis technology is the oscillating aerodynamic forces. A force measurement setup has been implemented to capture the forces on a three-bladed 12 kW open site prototype. The normal force showed good agreement with simulations. An aerodynamic torque could be estimated from the system. The total electrical torque in the generator was determined from electrical measurements. Both torque estimations lacked the expected aerodynamic ripple at three times per revolution. The even torque detected is an important result and more studies are required to confirm and understand it. The force measurement was also used to study the loads on the turbine in parked conditions. It was discovered that there is a strong dependence on wind direction and that there is a positive torque on the turbine at stand still. The results can assist to determine the best parking strategies for an H-rotor turbine. The studied concept also features diode rectification of the voltage from the permanent magnet synchronous generator. Diodes are considered a cheap and robust solution for rectification at the drawback of inducing ripple in the torque and output voltage. The propagation of the torque ripple was measured on the prototype and studied with simulations and analytical expressions. One key conclusion was that the mechanical driveline of the turbine is an effective filter of the diode induced torque ripple. A critical speed controller was implemented on the prototype. The controller was based on optimal torque control and according to the experiments and the simulations it was able to avoid a rotational speed span. Finally, the optimal torque control was evaluated for multiple turbines with diode rectification to a common DC-link. The setup can potentially reduce the overall complexity of wind farms. The simulations suggest that stability of the system can be obtained by controlling the DC-link load as a semi constant voltage. The thesis is based on nine papers of which six are treated in the thesis summary.

Les travaux visant au développement de capteurs passifs interrogeables sans fil pour sonder des températures supérieures à 600 °C s’inscrivent dans le projet européens SAWHOT. Des capteurs à ondes élastiques de surface sont modélisés, réalisés et caractérisés par une liaison radiofréquence. Le paramètre physique mesuré par ce capteur est la température, avec une mesure au-delà de 900°Cpour les applications de maintenance préventive des turbines à combustion ou pour le contrôle de procédés dans les fours de synthèse de nano-tubes de carbone. Les substrats piezoélectriques standards tels que le quartz ou le niobate de lithium ne sont pas envisageables : l’ensemble de ces travaux s’articule autour de la langasite, substrat piezoélectrique opérant jusqu’à 1470°C et ne présentant aucune température de transition (température de Curie) jusqu’à sa température de fusion située à 1470°C. Compte tenu de la vitesse des ondes élastiques de surface des coupes considérés et également des limitations imposées par les moyens de réalisations technologiques, ces résonateurs sont mesurés sans fil à une fréquence proche de la bande ISM centré en 434 MHz. Les dispositifs ainsi réalisés ont été encapsulés via une procédure innovante de mise en boîtier qui permet alors la mesure de capteurs à ondes élastiques de surface dans des environnements où la température dépasse 700°C. De nombreuses études expérimentales ont alors été menés dans le but d’évaluer les performances des capteurs à ondes élastiques de surface en terme de bilan de liaison radiofréquence, reproductible de la mesure, vieillissement au cours des cycles en températures / Development of wireless passive sensor for temperature measurement above 600°C has been performed in the frame of the European SAWHOT project. In this context, surface acoustic wave sensors have been designed, fabricated and characterized by radiofrequency measurement. Physical parameter measured by these sensors is the temperature, reaching values up to 900°C for monitoring in combustion engines andIn ovens used for carbon nano-tubes growth. In order to measure temperature in harsh environments, classical piezoelectric substrates are not usuable: langasite substrate has been considered as a favorable option since it exhibits no transition temperature and is able to operate until its exhibits no transition temperature and is able to operate until its melting temperature, at 1470 °C. regarding the parameters of the surface acoustic waves and the limitation of the fabrication process and devices, the resonators are measured wirelessly in the ISM band centered at 434 MHz (3μm of interdigital transducer period and a transducers with of 1μm). Two main manufacturing technologies are considered, stepper and nano-imprint technologies. The fabricated devices have been packaged by using an innovative process protecting the devices and allowing fir wireless measurements until 700°C. Multiple experiments have been performed in order to characterize the radiofrequency link between the reader and the sensor, the reproducibility of the measurement, the aging effect on the response of the device after high temperature cycles.

The diploma thesis deals with a design of a tester device, a selection and verification of a suitable method for comparing the piezoelectric properties of tested PVDF samples. In the introduction, a basic overview of the theory is important to understand the issue and the various branches of use of PVDF in the field of energy harvesting. The tester device includes a unimorph piezoelectric cantilever beam with tip mass, whose properties are described by three models: a model with N degrees of freedom reduced to one degree of freedom (NDOF), a single degree of freedom model (SDOF), both created in Matlab and a model for verifying results in FEM ANSYS Workbench program. The voltage time response and the voltage frequency response of the models is compared with each other. For two different PVDF samples, the voltage response to harmonic excitation is measured using a tester device, and the piezoelectric properties of one of them are determined using the NDOF and SDOF models.

No description available.