Structural health monitoring systems provide a promising route to real-time data for analyzing the current state of large structures. In the wake of two high-profile bridge collapses due to an aging highway infrastructure, the interest in implementing such systems into fracture-critical and structurally deficient bridges is greater now than at any point in history. Traditionally, these technologies have not been cost-effective as bridges lack existing wiring architecture and the addition of this is cost prohibitive. Modern wireless sensor networks (WSN) now present a viable alternative to traditional networking; however, these systems must incorporate localized power sources capable of decade-long operation with minimal maintenance. To this end, this thesis explores the development of two energy harvesting systems capable of long-term bridge deployment with minimal maintenance. First, an electromagnetic, linear, vibrational energy harvester is explored that utilizes the excitations from passing traffic to induce motion in a translating permanent magnet mass. This motion is then converted to electrical energy using Faraday’s law of induction. This thesis presents a review of vibrational energy harvesting literature before detailing the process of designing, simulating, prototyping, and testing a selected design. Included is an analysis of the effects of frequency, excitation amplitude, load, and damping on the power production potential of the harvester. Second, a solar energy harvester using photovoltaic (PV) panels is explored for powering the critical gateway component of the WSN responsible for data aggregation. As solar energy harvesting is a more mature technology, this thesis focuses on the methodologies for properly sizing a solar harvesting system and experimentally validating the selected design. Fabrication of the prototype system was completed and field testing was performed in Austin, TX. The results validate the selected system’s ability to power the necessary 14 W DC load with a 0° panel azimuth angle (facing direct south) and 45° tilt. / text

Wireless Sensor Networks (WSNets), consisting of a lot of Wireless Sensor Nodes (WSNs), play an important role in structural health and machine condition monitoring. But the WSNs provided by the current market cannot meet the diversity of application requirements because they have limited functions, unreliable node performance, high node cost, high system redundancy, and short node lifespan. The aim of the research is to design the architecture of a WSN with low power consumption and node cost, which can be dynamically configured according to application requirements for structural health and machine condition monitoring. This research investigates the improvement of node performance and reliability through the new design methodologies and the extension of node lifespan by interfacing energy harvesters and implementing node power management. The main contributions of the research are presented from the following aspects:1. Model development of node architecture for application diversityThe merits of model include: (1) The proposed node architecture can be dynamically configured in terms of application requirements for reducing system redundancy, power consumption and cost; (2) It supports multichannel signal measurement with the synchronous and asynchronous signal sampling modules and three interface circuits; (3)The model parameters can be calculated; (4) As the model is based on discrete electronic components, it can be implemented by using Components-Off-The-Shelf (COTS).2. A novel pipeline design of the built-in ADC inside a microprocessorThe merit of proposed pipeline solution lies in that the sampling time of the built-in ADCs is reduced to one third of the original value, when the ADC operates in sequence sampling mode based on multichannel signal measurement.3. Self-adjusting measurement of sampled signal amplitude This work provides a novel method to avoid the distortion of sampled signals even though the environmental signal changes randomly and over the sampling range of the node ADC. The proposed method can be implemented with four different solutions.4. Interface design to support energy harvesting The proposed interface will allow to: (1) collect the paroxysmal ambient energy as more as possible; (2) store energy to a distribution super-capacitor array; (3) harvest electrical energy at high voltage using piezoelectric materials without any transformer; (4) support the diversity of energy transducers; and (5) perform with high conversion efficiency.5. A new network task scheduling model for node wireless transceiver The model allows to: (1) calculate node power consumption according to network task scheduling; (2) obtain the optimal policy for scheduling network task.6. A new work-flow model for a WSN The model provides an easy way to (1) calculate node power consumption according to the work flow inside a WSN; (2) take fully advantage of the power modes of node electronic components rather than outside factors; (3) improve effectively node design.

This thesis is focused on design of piezoelectric energy harvester with additional nonlinear stiffness. Linear generator has very narrow resonance frequency bandwidth. It makes the resonance mechanism very sensitive to tuning up of the resonance frequency and it can be tuned only for one narrow vibration peak. The main idea for using of the vibration energy harvester with nonlinear stiffness is to make resonance frequency bandwidth wider, so the generator will be useable for more excitation frequencies. In this thesis is used generator Midé V21BL and additional nonlinear stiffness is realized with permanent magnets.

Diphenylalanine peptide (Phe-Phe or FF) is a very promising bio-material in the future wearable electronics application due to its self-assembly into nanotubes and nanoribbons with high shear piezoelectric coefficient which is comparable to traditional inorganic piezoelectric materials. In order to efficiently harvest piezoelectric response, alignment and unidirectional polarization of FF nanotubes are required. Most prior works show that there mainly two methods to achieve the alignment and unidirectional polarization. They are epitaxial growth and meniscus-driven dip-coating. However, they still have some disadvantages like low productivity or harsh conditions. In this work, we use inkjet printing technology to develop a scalable, programmable and patterns designable process for the fabrication of FF nanotubes. Most prior works use toxic solvent 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) to dissolve FF peptide. In our work, the ink only contains sustainable and ecofriendly solvent like acetic acid and ethylene glycol. In the inkjet printing process, patterns can be perfectly printed on the substrate of graphene and ethyl cellulose. The direction and length of FF nanoribbons are controllable. Aligned FF nanoribbons can be observed in the printed devices. Orthorhombic crystal structure is characterized by SEM and XRD. The piezoelectric performance of the device with aligned FF nanoribbons is much higher than the random FF based devices. The FF piezoelectric nanogenerator generates voltage, current, and power density of up to 1.49 V, 10.5 nA, and 4.4 nW/cm2, respectively, under a force of 50 N. Our results show the promising future of FF-based piezoelectric devices in self-powered and wearable electronics application. / Diphenylalanine peptide (Phe-Phe eller FF) är ett mycket lovande biomaterial i den framtida bärbara elektronikapplikationen pågrund av dess självmontering till nanorör och nanorband med hög piezoelektrisk koefficient som är jämförbar med traditionella oorganiska piezoelektriska material. För att effektivt skörda piezoelektrisk respons krävs inriktning och enkelriktad polarisering av FF-nanorör. De flesta tidigare arbeten visar att det huvudsakligen finns tvåmetoder för att uppnå inriktning och enkelriktad polarisering. De är epitaxiell tillväxt och menisk-driven dopp-beläggning. Men de har fortfarande vissa nackdelar som låg produktivitet eller svåra förhållanden. I detta arbete använder vi bläckstråleutskriftsteknik för att utveckla en skalbar, programmerbar och mönsterdesignbar process för tillverkning av FF-nanorör. De flesta tidigare verk använder giftigt lösningsmedel 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) för att lösa upp FF-peptid. I vårt arbete innehåller bläcket endast hållbara och miljövänliga lösningsmedel som ättiksyra och etylenglykol. I bläckstråleutskriftsprocessen kan mönster tryckas perfekt på substratet av grafen och etylcellulosa. Riktningen och längden på FF nanoband är kontrollerbara. Justerade FF-nanoband kan observeras i de utskrivna enheterna. Ortorhombisk kristallstruktur kännetecknas av SEM och XRD. Den piezoelektriska prestandan hos enheten med justerade FF-nanoband är mycket högre än de slumpmässiga FF-baserade enheterna. FF piezoelektriska nanogeneratorn genererar spänning, ström och effekttäthet på upp till 1,49 V, 10,5 nA respektive 4,4 nW/cm2 med en kraft på 50 N. Våra resultat visar den lovande framtiden för FF-baserade piezoelektriska enheter i sig själv -driven och bärbar elektronikapplikation.

Diphenylalanine peptide (Phe-Phe or FF) is a very promising bio-material in the future wearable electronics application due to its self-assembly into nanotubes and nanoribbons with high shear piezoelectric coefficient which is comparable to traditional inorganic piezoelectric materials. In order to efficiently harvest piezoelectric response, alignment and unidirectional polarization of FF nanotubes are required. Most prior works show that there mainly two methods to achieve the alignment and unidirectional polarization. They are epitaxial growth and meniscus-driven dipcoating. However, they still have some disadvantages like low productivity or harsh conditions. In this work, we use inkjet printing technology to develop a scalable, programmable and patterns designable process for the fabrication of FF nanotubes. Most prior works use toxic solvent 1,1,1,3,3,3-hexafluoro2-propanol (HFIP) to dissolve FF peptide. In our work, the ink only contains sustainable and ecofriendly solvent like acetic acid and ethylene glycol. In the inkjet printing process, patterns can be perfectly printed on the substrate of graphene and ethyl cellulose. The direction and length of FF nanoribbons are controllable. Aligned FF nanoribbons can be observed in the printed devices. Orthorhombic crystal structure is characterized by SEM and XRD. The piezoelectric performance of the device with aligned FF nanoribbons is much higher than the random FF based devices. The FF piezoelectric nanogenerator generates voltage, current, and power density of up to 1.49 V, 10.5 nA, and 4.4 nW/cm2, respectively, under a force of 50 N. Our results show the promising future of FFbased piezoelectric devices in self-powered and wearable electronics application. / Diphenylalanine peptide (Phe-Phe eller FF) är ett mycket lovande biomaterial i den framtida bärbara elektronikapplikationen på grund av dess självmontering till nanorör och nanorband med hög piezoelektrisk koefficient som är jämförbar med traditionella oorganiska piezoelektriska material. För att effektivt skörda piezoelektrisk respons krävs inriktning och enkelriktad polarisering av FFnanorör. De flesta tidigare arbeten visar att det huvudsakligen finns två metoder för att uppnå inriktning och enkelriktad polarisering. De är epitaxiell tillväxt och menisk-driven dopp-beläggning. Men de har fortfarande vissa nackdelar som låg produktivitet eller svåra förhållanden. I detta arbete använder vi bläckstråleutskriftsteknik för att utveckla en skalbar, programmerbar och mönsterdesignbar process för tillverkning av FF-nanorör. De flesta tidigare verk använder giftigt lösningsmedel 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) för att lösa upp FF-peptid. I vårt arbete innehåller bläcket endast hållbara och miljövänliga lösningsmedel som ättiksyra och etylenglykol. I bläckstråleutskriftsprocessen kan mönster tryckas perfekt på substratet av grafen och etylcellulosa. Riktningen och längden på FF nanoband är kontrollerbara. Justerade FF-nanoband kan observeras i de utskrivna enheterna. Ortorhombisk kristallstruktur kännetecknas av SEM och XRD. Den piezoelektriska prestandan hos enheten med justerade FF-nanoband är mycket högre än de slumpmässiga FF-baserade enheterna. FF piezoelektriska nanogeneratorn genererar spänning, ström och effekttäthet på upp till 1,49 V, 10,5 nA respektive 4,4 nW/cm2 med en kraft på 50 N. Våra resultat visar den lovande framtiden för FF-baserade piezoelektriska enheter i sig själv -driven och bärbar elektronikapplikation.

The project is about piezoelectric energy harvesters and piezoelectric bio-organic materials.Nowadays, various kinds of energy harvesters based on micro or nano materials are appliedinmanyelectronic applications, such as wearable devices and electricity generators. Amongthem, thepiezoelectric effect-based energy harvesters are more attractive in research and industryfields. Inrecent years, piezoelectric biomaterials become a popular option because they are availabletocouple electrical and mechanical energy in a biological, ecofriendly systemto generate electricityinreal time. Among them, γ- glycine crystals have been recently synthesized in wafer scale throughasimple polyvinyl alcohol (PVA)-assisted evaporation process exhibiting good piezoelectricperformance. However, so far there are no metal-free energy-harvesting devices basedonPVA-glycine film to enable green manufacturing. In this project, we proposed the direct inkwritingorganic PEDOT:PSS electrodes and PVA-glycine-PVA piezoelectric crystals to fabricate metal-freeenergy harvesters. The output voltage reaches 1.5 V at a load resistance of 500 MΩandunderaforce of 10 N. The performance is comparable to other glycine-based devices in recent literature.Our scalable, sustainable and low-cost printing process is expected to greatly contribute tothefieldof biomaterials-based piezoelectric energy harvesting. / Projektet handlar om piezoelektriska energiskördare och piezoelektriska bioorganiska material. Nuförtiden används olika typer av energiskördare baserade på mikro- eller nanomaterial i mångaelektroniska applikationer, såsom bärbara enheter och elgeneratorer. Bland dem är de piezoelektriskaeffektbaserade energiskördarna mer attraktiva inom forsknings- och industriområden. På senare år harpiezoelektriska biomaterial blivit ett populärt alternativ eftersom de är tillgängliga för att koppla elektrisk och mekanisk energi i ett biologiskt, miljövänligt system för att generera elektricitet i realtid. Bland dem har γ-glycinkristaller nyligen syntetiserats i waferskala genom en enkel polyvinylalkohol (PVA)-assisterad förångningsprocess som uppvisar god piezoelektrisk prestanda. Än så länge finnsdet dock inga metallfria energiskördande enheter baserade på PVA-glycinfilm för att möjliggöra gröntillverkning. I detta projekt föreslog vi direkt bläckskrivande organiska PEDOT:PSS-elektroder ochPVA-glycin-PVA piezoelektriska kristaller för att tillverka metallfria energiskördare. Utspänningennår1,5 V vid en belastningsresistans på 500 MΩ och under en kraft på 10 N. Prestandan är jämförbar medandra glycinbaserade enheter i nyare litteratur. Vår skalbara, hållbara och billiga utskriftsprocess förväntas i hög grad bidra till området för biomaterialbaserad piezoelektrisk energiskörd.

Ces travaux de thèse portent sur le développement de nouveaux systèmes piézoélectriques récupérateurs d’énergie à partir de vibrations mécaniques environnementales. L’objectif recherché est d’apporter des solutions à certaines contraintes fortes liées à la miniaturisation de ces systèmes, en vue de leur intégration en technologie MEMS. Les 2 axes majeurs suivis lors de ces travaux sont :(i) la nanostructuration par porosification du substrat silicium. Ce procédé permet de créer des zones fonctionnalisées possédant des propriétés locales de masse volumique et de rigidité plus faibles que celles du substrat silicium. Ceci permet d’une part d’améliorer le coefficient de couplage électromécanique global de la structure et, d’autre part, de maintenir la fréquence de résonance du mode fonctionnel dans une gamme fréquentielle basse (< que 1KHz) compatible avec le spectre de nombreuses sources vibratoires usuelles. Une série de modélisation par éléments finis d’un convertisseur type (poutre avec masse sismique) a établi les paramètres dimensionnels optimaux de la zone nanostructurée. L’efficacité de ce procédé de nanostructuration localisée a ensuite été évaluée expérimentalement sur des membranes en silicium. Il a été observé une réduction de la fréquence de résonance du mode fondamental, tout en minimisant les pertes par un choix judicieux de l’emplacement et de la largeur de la zone poreuse. (ii) Le développement de dispositifs récupérateurs à sensibilité multidirectionnelle. Ces dispositifs permettent de récupérer l’énergie quel que soit la direction de la sollicitation externe. Ils exploitent 3 modes propres distincts de flexion sollicités chacun par une composante particulière (ax, ay ou az) du vecteur accélération caractéristique de la sollicitation. Ces dispositifs basés sur une structure planaire de type double poutres orthogonales avec masse sismique centrale sont facilement intégrables et peuvent être déclinés de l’échelle centimétrique à l’échelle millimétrique en utilisant dans ce cas les technologies de type MEMS. Un modèle analytique simple a d’abord mis à jour les mécanismes énergétiques qui permettent d’obtenir une quantité d’énergie constante lorsque le dispositif est soumis à un vecteur sollicitation de direction quelconque. L’optimisation du coefficient de couplage électromécanique de chaque mode fonctionnel, ainsi que l’ajustement de leur fréquence de résonance ont été obtenu à l’aide d’un modèle à éléments finis. L’ensemble de ces résultats théoriques a été expérimentalement validé à l’aide de prototypes centimétriques. / This thesis work focuses on the development of new piezoelectric energy recovery systems from environmental mechanical vibration. The goal is to provide solutions to some strong constraints on the miniaturization of these systems, their integration in MEMS technology. The 2 major lines followed in this work are: (i) the nanostructuring by porosification silicon substrate. This method allows to create functionalized areas having local properties of density and lower rigidity than those of the silicon substrate. This allows on the one hand to improve the overall electromechanical coupling coefficient of the structure and, secondly, to maintain the resonant frequency of the operational mode in a low frequency range (< 1KHz) compatible with the spectrum of Many conventional vibratory sources. A series of finite element modeling of a type converter (beam with seismic mass) established the optimum dimensional parameters of nanostructured area. The effectiveness of this localized nanostructuring method was then evaluated experimentally on silicon membranes. It was observed a reduction of the resonance frequency of the fundamental mode, while minimizing losses by a judicious choice of the location and the width of the porous zone. (Ii) The development of recovery devices multidirectional sensitivity. These devices allow to recover energy regardless of the direction of the external load. They use 3 different eigenmodes bending each solicited by a particular component (ax, ay and az) vector solicitation characteristic acceleration. These devices based on a planar structure type double orthogonal beams with central seismic mass can be easily integrated and can be broken down to centimeter scale at the millimeter scale using in this case the MEMS technologies. A simple analytical model was first updated energy mechanisms that enable a constant amount of energy when the device is subjected to a bias vector in any direction. The optimization of the electromechanical coupling coefficient of each functional mode, and the adjustment of their resonance frequency were obtained using a finite element model. All these theoretical results has been experimentally validated using centimeter prototypes.

Orientador: Michael John Brennan / Abstract: The advances in microelectromechanical systems to power supply devices for monitoring the structural integrity, mainly for applications in remote areas or with difficult access, have made energy harvesting from ambient vibration a highly researched topic. Although several electromechanical mechanisms have been proposed for applications in a variety of fields, harvesting energy from railway track vibrations is relatively new, and only a small amount of research is ongoing in this topic. This thesis aims to determine the factors that govern the sleeper vertical vibration induced by a passing train, develop a methodology to emulate this vibration in a laboratory-based system and to derive a model of a load resistance attached to a linear electromagnetic transducer to determine the optimum energy harvested. The study shows the importance of knowing the vibration behaviour of the sleeper in order to tune the energy harvester to the correct excitation frequency. A comparison between piezoelectric and electromagnetic transducers is performed using a two-port network model to determine which transducer performs better for low frequency vibration. To emulate sleeper vibration due to a passing train using an electrodynamic shaker, a compensator filter is designed to remove the system dynamics. An analytical investigation into the energy dissipated by a load resistance attached to an electromagnetic transducer when subject to a time-limited base excitation, which may include the transie... (Complete abstract click electronic access below) / Resumo: Avanços em sistemas micro eletromecânico para fornecer energia à dispositivos para monitoramento de integridade estrutural, principalmente para aplicações em áreas remotas ou de difícil acesso, fez de extração de energia a partir de vibrações contidas no ambiente um tópico de pesquisa em destaque. Apesar de que diversos mecanismos eletromecânicos já foram propostos em uma variedade de aplicações, extração de energia à partir de vibrações em linhas férreas é, relativamente, novo e somente algumas pesquisas estão sendo realizadas sobre esse tópico. Esta Tese busca determinar os fatores que governam a vibração vertical do dormente induzida devido a passagem de um trem, desenvolver uma metodologia para emular esta vibração em um sistema em laboratório e derivar um modelo para um transdutor linear eletromagnético com uma carga resistiva acoplada. O estudo mostrou a importância de conhecer o comportamento vibracional do dormente de modo a sintonizar o extrator de energia com a frequência correta de excitação. Uma comparação entre transdutores piezoelétrico e eletromagnético é realizado utilizando um modelo quadripolo para determinar qual transdutor tem um melhor desempenho para vibrações em baixa frequência. Para emular a vibração do dormente devido a passagem de um trem em um agitador eletrodinâmico, um filtro compensador é projetado para remover a dinâmica do sistema. Uma investigação analítica da energia dissipada pela carga resistiva acoplada à um transdutor eletromagnético qua... (Resumo completo, clicar acesso eletrônico abaixo) / Doutor

This thesis project investigates, analyzes, designs, simulates, constructs and tests a dual-axis solar tracker system to track the sun and concentrates the heat of the sunlight, using a Fresnel lens, into a small area, which is above of an evaporator, to increase the temperature of the seawater to convert it into freshwater. The dual-axis solar tracker was designed with the main objectives that the structure was portable, dismountable, lightweight, low cost, corrosion resistant, wires inside pipes, accurate, small size, follow the sun automatically, off-grid (electrical), use green energy (solar powered), and has an empty area right below of the lens. First, a 500 mm diameter flat Fresnel lens was selected and simulated based on an algorithmic method achieved by a previous PhD student at UNT using MATLAB®, to give the optimization lens dimensions. The lens profile was drawn with AutoCAD®, then output profile lens was simulated in COMSOL Multiphysics®. The objective was to provide the high efficiency, optimum and high precision of the focal rays and heat to the receiver of the evaporator. A novel dual-axis solar tracker system was then designed that is portable, dismountable, lightweight and corrosion resistant. The solar tracker tracks the sun in two axis of rotation automatically during the day time, maximizing the angles of inclination on each axis. After testing computer simulations, the dual-axis solar tracker system was constructed and tested. Last, a detailed cost analysis was performed of the entire project. The outcome of this work can be applied for desalination seawater purposes or other any Fresnel lens application that require a focal high temperature directed by dual-axis solar tracker system.

In this thesis, a miniaturized energy harvester system is developed. The energy harvester converts fluid kinetic energy into electrical energy without using any rotating components. The working principle of the energy harvester is based on the so called vortex-induced vibration. Such systems have the potential to provide energy for wireless sensor networks in the field of inline measurements for gas, oil or water transportation systems. The theoretical background of the vortex-induced vibration (VIV) is studied. Based on the studies, a fluid-structure interaction simulation is carried out to optimize the structure of the energy harvester. As result, the conversion efficiency is significantly improved, which is experimentally confirmed. A series of demonstrators are manufactured according to the simulation and optimization results. It is tested on a self-constructed test bench. To further improve the performance, an electromagnetic generator is proposed, and therefore, a multimethod demonstrator realized. The demonstrators are working in air flow already at a velocity of 2 m/s, and reach the maximum efficiency at 3.6 m/s. This performance ranks among the best published results and is discussed in detail. / In der vorliegenden Arbeit wird ein miniaturisiertes Energiegewinnungssystem entwickelt, das unter Verzicht auf rotierende Komponenten kinetische Strömungsenergie in elektrische Energie umwandelt. Die Funktion dieses Wandlers basiert auf der sogenannten wirbelinduzierten Vibration. Derartige Systeme besitzen unter anderem das Potenzial, drahtlose Sensornetzwerke zur Erfassung von Messdaten in Gas-, Öl- oder Wassertransportsystemen mit Energie zu versorgen zu können. In der Arbeit wird der theoretische Hintergrund der wirbelinduzierten Vibration untersucht und darauf basierend werden Fluid-Struktur-Wechselwirkungssimulationen zur Strukturoptimierung durchgeführt in deren Ergebnis eine theoretische Verbesserung der Effizienz des Wandlers um ein Mehrfaches erreicht wird, die auch praktisch bestätigt wird. Unter Berücksichtigung der Simulations- und Optimierungsergebnisse wurden eine Reihe von Demonstratoren gefertigt, die auf einem selbst konstruierten Prüfstand getestet wurden. Zur weiteren Erhöhung der Leistungsfähigkeit des Wandlers wird ein zusätzlicher elektromagnetischer Generator vorgeschlagen und damit ein Multi-Methoden-Demonstrator technisch realisiert. Die Demonstratoren arbeiten in strömender Luft bereits bei Geschwindigkeiten von 2 m/s und erreichen bei 3,6 m/s ihre maximale Effizienz. Die erreichten Ergebnisse ordnen sich im Vergleich mit denen aus entsprechenden Publikationen vorn ein und werden ausführlich diskutiert.