Vibration-based energy harvesting has been investigated by several researchers over the last decade. The ultimate goal in this research field is to power small electronic components (such as wireless sensors) by using the vibration energy available in their environment. Among the basic transduction mechanisms that can be used for vibration-to-electricity conversion, piezoelectric transduction has received the most attention in the literature. Piezoelectric materials are preferred in energy harvesting due to their large power densities and ease of application. Typically, piezoelectric energy harvesters are cantilevered structures with piezoceramic layers that generate alternating voltage output due to base excitation. This work presents distributed-parameter electromechanical models that can accurately predict the coupled dynamics of piezoelectric energy harvesters. First the issues in the existing models are addressed and the lumped-parameter electromechanical formulation is corrected by introducing a dimensionless correction factor derived from the electromechanically uncoupled distributed-parameter solution. Then the electromechanically coupled closed-form analytical solution is obtained based on the thin-beam theory since piezoelectric energy harvesters are typically thin structures. The multi-mode electromechanical frequency response expressions obtained from the analytical solution are reduced to single-mode expressions for modal vibrations. The analytical solutions for the electromechanically coupled voltage response and vibration response are validated experimentally for various cases. The single-mode analytical equations are then used for deriving closed-form relations for parameter identification and optimization. Asymptotic analyses of the electromechanical frequency response functions are given along with expressions for the short-circuit and the open-circuit resonance frequencies. A simple experimental technique is presented to identify the optimum load resistance using only a single resistor and an open-circuit voltage measurement. A case study is given to compare the power generation performances of commonly used monolithic piezoceramics and novel single crystals with a focus on the effects of plane-stress material constants and mechanical damping. The effects of strain nodes and electrode configuration on piezoelectric energy harvesting are discussed theoretically and demonstrated experimentally. An approximate electromechanical solution using the assumed-modes method is presented and it can be used for modeling of asymmetric and moderately thick energy harvester configurations. Finally, a piezo-magneto-elastic energy harvester is introduced as a non-conventional broadband energy harvester. / Ph. D.

Converting vibrations to a usable form of energy has been the topic of many recent investigations. The ultimate goal is to convert ambient or aeroelastic vibrations to operate low-power consumption devices, such as microelectromechanical systems, heath monitoring sensors, wireless sensors or replacing small batteries that have a nite life span or would require hard and expensive maintenance. The transduction mechanisms used for transforming vibrations to electric power include: electromagnetic, electrostatic, and piezoelectric mechanisms. Because it can be used to harvest energy over a wide range of frequencies and because of its ease of application, the piezoelectric option has attracted significant interest. In this work, we investigate the performance of different types of piezoelectric energy harvesters. The objective is to design and enhance the performance of these harvesters. To this end, distributed-parameter and phenomenological models of these harvesters are developed. Global analysis of these models is then performed using modern methods of nonlinear dynamics. In the first part of this Dissertation, global nonlinear distributed-parameter models for piezoelectric energy harvesters under direct and parametric excitations are developed. The method of multiple scales is then used to derive nonlinear forms of the governing equations and associated boundary conditions, which are used to evaluate their performance and determine the effects of the nonlinear piezoelectric coefficients on their behavior in terms of softening or hardening. In the second part, we assess the influence of the linear and nonlinear parameters on the dynamic behavior of a wing-based piezoaeroelastic energy harvester. The system is composed of a rigid airfoil that is constrained to pitch and plunge and supported by linear and nonlinear torsional and flexural springs with a piezoelectric coupling attached to the plunge degree of freedom. Linear analysis is performed to determine the effects of the linear spring coefficients and electrical load resistance on the flutter speed. Then, the normal form of the Hopf bifurcation (flutter) is derived to characterize the type of instability and determine the effects of the aerodynamic nonlinearities and the nonlinear coefficients of the springs on the system's stability near the bifurcation. This is useful to characterize the effects of different parameters on the system's output and ensure that subcritical or "catastrophic" bifurcation does not take place. Both linear and nonlinear analyses are then used to design and enhance the performance of these harvesters. In the last part, the concept of energy harvesting from vortex-induced vibrations of a circular cylinder is investigated. The power levels that can be generated from these vibrations and the variations of these levels with the freestream velocity are determined. A mathematical model that accounts for the coupled lift force, cylinder motion and generated voltage is presented. Linear analysis of the electromechanical model is performed to determine the effects of the electrical load resistance on the natural frequency of the rigid cylinder and the onset of the synchronization region. The impacts of the nonlinearities on the cylinder's response and energy harvesting are then investigated. / Ph. D.

O desenvolvimento deste trabalho foi motivado pela alta demanda de novas aplicações para o mercado do consumidor que necessitam de sistemas de transmissão e recepção de dados sem fio trabalhando na região de ondas milimétricas (mmW - entre 30 GHz e 300 GHz). Para estes tipos de sistemas, os defasadores são cruciais por definir o custo e o tamanho do dispositivo final. A pesquisa bibliográfica mostra que a melhor opção são os defasadores passivos do tipo linha carregada que utilizam Sistemas Microeletromecânicos (MEMS) como elemento de ajuste para a mudança de fase. Por esse motivo neste trabalho foi feito o estudo de diferentes tecnologias para o desenvolvimento de defasadores baseados em MEMS distribuídos e linhas de transmissão com efeito de ondas lentas de tipo shielded-CoPlanar Stripline (S-CPS) e shielded-Coplanar Waveguide (S-CPW). Foram estudadas três diferentes tecnologias: a tecnologia CMOS; a tecnologia dedicada desenvolvida pelo Laboratoire d\'électronique des technologies de l\'information (CEA-Leti) e a tecnologia in-house desenvolvida no Laboratório de Microeletrônica da Universidade de São Paulo. Utilizando a tecnologia CMOS foram fabricadas linhas de transmissão de tipo S-CPS utilizando a tecnologia de 250 nm da IHP (Innovations for High Performance Microelectronics) e a tecnologia de 0,35 µm da AMS (Austria Micro Systems). A tecnologia de 0,35 µm da AMS foi utilizada também para o desenvolvimento de defasadores de 2-bits e 3-bits baseados em linhas de transmissão de tipo S-CPW. Para estes defasadores foi definido um processo de liberação da camada de blindagem, reprodutível, que permitiu a atuação do dispositivo. Outros defasadores baseados em S-CPW que foram desenvolvidos anteriormente com a tecnologia dedicada CEA-LETI, foram modelados eletrostaticamente utilizando o Comsol MultiPhysics e o Ansys Workbench. Os modelos desenvolvidos permitiram entender o comportamento eletromecânico do defasador e foram utilizados reprojetar o defasador com um desempenho otimizado. Finalmente, visando o desenvolvimento dos dispositivos otimizados utilizando a tecnologia in house com os materiais e métodos disponíveis no Laboratório de Microeletrônica da USP (LME-USP), foram estudadas algumas etapas críticas do processo de fabricação. / The development of this work is motivated by the high demand for new applications for the consumer market that require wireless systems for data transmission and reception working in the millimeter wave region (mmW - between 30 GHz and 300 GHz). For these kinds of systems, the phase shifter are crucial to define the cost and size of the final device. The bibliographical research shows that the best option are the passive load line-type phase shifters using Microelectromechanical Systems (MEMS) as tuning element. Therefore, in this work, the study of different technologies for the development of phase shifter based on distributed MEMS and slow-wave transmission lines. The two types of transmission lines considered were the shielded-CoPlanar Stripline (S-CPS) and shielded-Coplanar Waveguide line (S-CPW). Three different technologies were studied: CMOS technology; the dedicated technology developed by the Laboratoire d\'électronique des technologies de l\'information (CEA-Leti) and the in-house technology developed at the Microelectronics Laboratory of the University of São Paulo. Using the CMOS technology, S-CPS-type transmission lines were fabricated using IHP\'s 250 nm CMOS technology and AMS\'s 0.35 µm CMOS technology. AMS\'s 0.35 µm technology has also been used for the development of 2-bit and 3-bit phase-shifters based on S-CPW type transmission lines. For these phase shifters, a reproducible shielding layer release process was defined that allowed the device to operate. Also, another phase shifter based in S-CPW-type transmission lines that were previously developed with dedicated CEA-LETI technology was electrostatically modeled using Comsol MultiPhysics and Ansys Workbench. The developed models allowed to understand the electromechanical behavior of the phase shifter and was used for a new design of the phase shifter with an optimized performance. Finally, in order to develop the optimized devices using the in-house technology with the materials and methods available at the USP Microelectronics Laboratory (LME-USP), some critical stages of the fabrication process were studied.

O desenvolvimento deste trabalho foi motivado pela alta demanda de novas aplicações para o mercado do consumidor que necessitam de sistemas de transmissão e recepção de dados sem fio trabalhando na região de ondas milimétricas (mmW - entre 30 GHz e 300 GHz). Para estes tipos de sistemas, os defasadores são cruciais por definir o custo e o tamanho do dispositivo final. A pesquisa bibliográfica mostra que a melhor opção são os defasadores passivos do tipo linha carregada que utilizam Sistemas Microeletromecânicos (MEMS) como elemento de ajuste para a mudança de fase. Por esse motivo neste trabalho foi feito o estudo de diferentes tecnologias para o desenvolvimento de defasadores baseados em MEMS distribuídos e linhas de transmissão com efeito de ondas lentas de tipo shielded-CoPlanar Stripline (S-CPS) e shielded-Coplanar Waveguide (S-CPW). Foram estudadas três diferentes tecnologias: a tecnologia CMOS; a tecnologia dedicada desenvolvida pelo Laboratoire d\'électronique des technologies de l\'information (CEA-Leti) e a tecnologia in-house desenvolvida no Laboratório de Microeletrônica da Universidade de São Paulo. Utilizando a tecnologia CMOS foram fabricadas linhas de transmissão de tipo S-CPS utilizando a tecnologia de 250 nm da IHP (Innovations for High Performance Microelectronics) e a tecnologia de 0,35 µm da AMS (Austria Micro Systems). A tecnologia de 0,35 µm da AMS foi utilizada também para o desenvolvimento de defasadores de 2-bits e 3-bits baseados em linhas de transmissão de tipo S-CPW. Para estes defasadores foi definido um processo de liberação da camada de blindagem, reprodutível, que permitiu a atuação do dispositivo. Outros defasadores baseados em S-CPW que foram desenvolvidos anteriormente com a tecnologia dedicada CEA-LETI, foram modelados eletrostaticamente utilizando o Comsol MultiPhysics e o Ansys Workbench. Os modelos desenvolvidos permitiram entender o comportamento eletromecânico do defasador e foram utilizados reprojetar o defasador com um desempenho otimizado. Finalmente, visando o desenvolvimento dos dispositivos otimizados utilizando a tecnologia in house com os materiais e métodos disponíveis no Laboratório de Microeletrônica da USP (LME-USP), foram estudadas algumas etapas críticas do processo de fabricação. / The development of this work is motivated by the high demand for new applications for the consumer market that require wireless systems for data transmission and reception working in the millimeter wave region (mmW - between 30 GHz and 300 GHz). For these kinds of systems, the phase shifter are crucial to define the cost and size of the final device. The bibliographical research shows that the best option are the passive load line-type phase shifters using Microelectromechanical Systems (MEMS) as tuning element. Therefore, in this work, the study of different technologies for the development of phase shifter based on distributed MEMS and slow-wave transmission lines. The two types of transmission lines considered were the shielded-CoPlanar Stripline (S-CPS) and shielded-Coplanar Waveguide line (S-CPW). Three different technologies were studied: CMOS technology; the dedicated technology developed by the Laboratoire d\'électronique des technologies de l\'information (CEA-Leti) and the in-house technology developed at the Microelectronics Laboratory of the University of São Paulo. Using the CMOS technology, S-CPS-type transmission lines were fabricated using IHP\'s 250 nm CMOS technology and AMS\'s 0.35 µm CMOS technology. AMS\'s 0.35 µm technology has also been used for the development of 2-bit and 3-bit phase-shifters based on S-CPW type transmission lines. For these phase shifters, a reproducible shielding layer release process was defined that allowed the device to operate. Also, another phase shifter based in S-CPW-type transmission lines that were previously developed with dedicated CEA-LETI technology was electrostatically modeled using Comsol MultiPhysics and Ansys Workbench. The developed models allowed to understand the electromechanical behavior of the phase shifter and was used for a new design of the phase shifter with an optimized performance. Finally, in order to develop the optimized devices using the in-house technology with the materials and methods available at the USP Microelectronics Laboratory (LME-USP), some critical stages of the fabrication process were studied.

Depuis plusieurs années les chiffres de l'insécurité routière montrent la nécessité de développer un outil technologique qui vise à connaitre le comportement de véhicules deux roues motorisés (2RM) afin d'améliorer leursécurité. De cette problématique découle nos travaux de recherche qui s'inscrivent dans le cadre de projet METRAMOTO (MEsure du TRAfic des deux-roues MOTOrisés pour la sécurité routière et l'évaluation des risques)L’objectif principal visé concerne la modélisation, le dimensionnement et l'optimisation d'un capteur hybride constitué d'une part de boucles électromagnétiques et d'autre part de capteurs de chocs piézo-électriques. L’idée consiste à utiliser les boucles électromagnétiques pour discriminer la présence des 2RM de celle des autresvéhicules, associées à des segments piézo-électriques pour détecter le choc produit par le passage des roues desdifférents véhicules, le tout associé à un algorithme de gestion et de traitement de données. Aujourd'hui redimensionnement des systèmes de détection à base de boucles électromagnétiques ou de câble piézo-électriquese fait de manière expérimentale sur des sites contrôlés en utilisant plusieurs types de véhicules. Cette technique gourmande en temps nécessite une série importante d'essais couteux et dangereux. La présente étude a pour butde modéliser les différentes interactions entre le capteur hybride étudié et les véhicules en vue de son dimensionnement. Des modèles électromagnétiques et électromécaniques sont développés pour décrire les différentes interactions se produisant entre les boucles électromagnétiques d'une part, les boucles électromagnétiques et les véhicules d'autre part ainsi que celles des roues de véhicules et le câble piézoélectrique.Sur la base de ces modèles établis, une démarche générale est élaborée conduisant au dimensionnement du capteur hybride pour une route donnée. Nous nous sommes également intéressés au traitement des données issues du capteur hybride pour lesquelles nous proposons une approche d'identification des différentes catégories de véhicules dont les 2RM. Deux configurations de capteurs pour deux routes différentes sont alors proposées.Elles sont associées à des algorithmes de traitement de données permettant l'acquisition des signaux de boucles et de câbles, la distinction des différents types de véhicules, l'estimation de la position des véhicules sur la chaussée ainsi que la mesure de la vitesse de véhicules. / For several years the road safety numbers show the need to develop a technological tool that aims to know thepowered two wheelers vehicles behavior (2PW) to improve their security. From this problematic arise our researchworks that come under the project METRAMOTO (Powered two wheelers traffic measurement for road safety andrisks assessment). The main objective is modeling, sizing and optimization of an hybrid sensor consisted ofelectromagnetic loops and piezoelectric shock sensors. The idea is to use electromagnetic loops to discriminate the2PW presence from the other vehicles, combined with piezoelectric segments to detect the shocks produced by thevehicles wheels passage, all associated with a management algorithm and data processing. Today the sizing of thedetection systems based on electromagnetic loops or piezoelectric cables is done experimentally on controlled sitesusing several vehicles types. This technique requires significant test series which are costly and dangerous. Thisstudy aims to modeling the different interactions between the studied sensor and vehicles in order to its sizing.Electromagnetic and electromechanical models are developed to describe the different interactions that take placebetween electromagnetic loops on the one hand, between electromagnetic loops and vehicles on the other handand those between vehicle wheels and piezoelectric cable. On the basis of established models, a general approachis elaborated driving to sizing the hybrid sensor for any given road. We are also interested to the data processingcoming from the hybrid sensor for which we propose an approach to identifying the different vehicle categoriesincluding the 2PW. Two sensor configurations for two different roads are then proposed. They are associated atdata processing algorithms allowing the acquisition of loops and cables signals, the distinction between the differentvehicles classes, the estimation of the vehicles positions on the road and the measuring of their speed.