Thèses sur le sujet « Fil flexible »

In the last decade, cellular networks have been characterized by an ever-growing user data demand that pushed for more and more network capacity to be satisfied. This caused increasing capacity shortfall and coverage issues, aggravated by inefficient fixed spectrum management policies and obsolete network structures. The development of new technologies and spectrum management policies is seen as a necessary step to take, in order to cope with these issues. Concerning the latter aspect, a significant research effort has been made since the beginning of the century, to investigate the advantages brought by flexible management paradigms, such as new dynamic spectrum access (DSA) schemes based on cognitive radio (CR). On the other hand, technological advancements have been proposed by new standards for mobile communications as well, to guarantee capacity enhancements over current networks. From a practical point of view, new approaches to network planning have been proposed together with purely technical solutions, to frame next generation cellular networks capable of meeting the identified target performance to satisfy the user data demands. Accordingly, new hierarchical approaches to network planning, where a tier of macro-cell base stations (MBSs) is underlaid with a tier of massively deployed low-power small-cell base stations (SBSs), are seen as promising candidates to achieve this scope. The resulting two-tiered network layout may improve the capacity of current networks in several ways, thanks to a better average link quality between the devices, a more efficient usage of spectrum resources and a potentially higher spatial reuse. In this thesis, we focus on the challenging problem arising when the two tiers share the transmit band, to capitalize on the available spectrum and avoiding possible inefficiencies. In this case, the coexistence of the two tiers is not feasible, if suitable interference management techniques are not designed to mitigate/cancel the mutual interference generated by the active transmitters in the network. This thesis is divided in three main parts, and proposes a rather exhaustive approach to the development of a new DSA technique, to go from the theoretical basis up to a proof-of-concept development. We first analyze a simplified two-tiered network obtained when deploying an SBS within the coverage area of a pre-existing MBS. We impose that the physical layer strategy adopted in the first tier, i.e., orthogonal frequency division multiplexing (OFDM), must be left untouched. The rationale for this is that we aim the guaranteeing a higher compliance of any proposed solution with the legacy single-tier network structure. Accordingly, we propose a novel technology called cognitive interference alignment (CIA), to be adopted uniquely in the second tier, to allow the two tiers to operate side-by-side in a CR setting. Afterwards, we consider a multi-user extension of the two-tiered network, considering the presence of several SBSs in the second tier. We show how the feasibility of the proposed approach can be extended to such scenarios, designing both a centralized and a distributed approach to manage the multi-user interference in the second tier. The performance of both solutions is evaluated for perfect and imperfect channel state information at the transmitter (CSIT) assumptions, and comparisons with state-of-the-art approaches are provided. Practical implementations issues of both solutions are identified, enlightening main features and drawbacks, and discussing possible solutions. In the last part of the thesis, we gradually take a step forward from the theoretical basis provided in the first two parts, up to a proof-of-concept development of a hybrid transceiver based on the proposed solution. Specifically, we show how the applicability of CIA is not limited to CR settings, and propose an application of this technique to enhance the energy efficiency of a standalone OFDM femto-cell base station (FBS), typical example of new generation low-power device adopted in heterogeneous network deployments. We investigate the enhancements that can be achieved for different channel conditions and statistics and discuss the impact of the power allocation strategy adopted by the FBS on these results. We finally design a working reconfigurable transceiver based on a software defined radio (SDR) approach, to implement devices capable of transmitting/receiving OFDM/CIA signals, or a flexible combination of both. We conclude the thesis by adopting this new tool to validate the theoretical results of the energy efficiency enhancement solution, showing the effectiveness and merit of both CIA and the designed reconfigurable transceiver.
Nell'ultimo decennio, le reti cellulari sono state caratterizzate da una crescita costante della richiesta di dati da parte degli utenti. Unito all'inefficienza delle politiche di gestione dello spettro adottate e all'obsolescenza delle infrastrutture di rete, questo ha generato una crescente necessità di maggiore capacità e copertura di rete. Lo sviluppo di più efficienti politiche di gestione dello spettro radio e di nuove tecnologie è un passo necessario per far fronte a queste problematiche. In questo senso, i vantaggi apportati da nuovi e flessibili schemi di gestione dello spettro, come il cosiddetto dynamic spectrum access (DSA) e gli approcci di tipo cognitive radio (CR), sono stati largamente studiati sin dagli inizi del secolo. Nuove basi per le reti cellulari di prossima generazione sono state poste anche dai più recenti standard, le cui innovazioni tecnologiche promettono un sostanziale aumento di capacità rispetto alle reti esistenti. Oltre alle innovazioni puramente tecniche, le soluzioni proposte per strutturare reti cellulari evolute, in grado di fornire elevate performance e soddisfare le richieste degli utenti, prevedono nuovi paradigmi che ne guidino la progettazione. In questo senso, approcci gerarchici al network planning, risultanti in reti a due livelli, in cui un livello di stazioni di base di tipo macro (MBS) viene affiancato da un livello di stazioni di base di tipo small (SBS), sono considerati estremamente promettenti. Queste nuove reti a due livelli potranno aumentare la capacità delle reti attuali in molti modi, grazie a minori attenuazioni medie nei canali tra i dispositivi, un uso più efficiente della risorsa spettrale e una miglior copertura di rete. Il lavoro presentato in questa tesi è concentrato sulla coesistenza tra i due livelli di rete, quando questi adottano la stessa banda in trasmissione per raggiungere un uso più efficiente della risorsa spettrale. In questo caso, se l'interferenza mutualmente generata dai trasmettitori attivi nei due livelli di rete non viene attenuata o eliminata da adeguati meccanismi per la gestione dell'interferenza, la coesistenza può risultare problematica, quando non impossibile. Questa tesi è suddivisa in tre parti e propone un ampia analisi che porta allo sviluppo di una nuova tecnica di tipo DSA, partendo dalle basi teoriche e arrivando allo sviluppo di un proof-of-concept. Il primo caso studiato è dato da una rete a due livelli semplificata, ottenuta considerando la presenza di una sola SBS all'interno del raggio di copertura di una MBS preesistente. Per garantire la compatibilità delle soluzioni proposte con le operazioni di una classica rete a singolo livello, si impone che la tecnologia di strato fisico adottata dalla MBS, i.e., orthogonal frequency division multiplexing (OFDM), non debba prevedere alcuna modifica. Di conseguenza, le relazioni tra i due livelli di rete vengono strutturate secondo il modello CR, e viene proposta una nuova tecnica per realizzare la coesistenza dei due livelli chiamata cognitive interference alignment (CIA), adottata unicamente dalla SBS. In seguito, l'analisi viene estesa ad una rete multi-utente, considerando la presenza di più di una SBS all'interno del raggio di copertura della MBS preesistente. La fattibilità e l'efficacia di CIA viene analizzata in questo contesto. Di conseguenza, vengono proposte strategie centralizzate e distribuite per la gestione dell'interferenza multi-utente, causata dalla presenza di più SBS all'interno del secondo livello di rete. L'analisi delle prestazioni della rete a due livelli viene effettuata per entrambi gli approcci, in caso di disponibilità di stime di canale al trasmettitore sia perfette sia imperfette (perfect e imperfect CSIT). Questa parte si conclude identificando le problematiche e i meriti principali legati all'implementazione pratica degli approcci proposti, sia centralizzati che distribuiti, e discutendone possibili soluzioni. Nell'ultima parte della tesi, l'analisi si sposta gradualmente da un approccio di tipo teorico ad uno di tipo pratico, portando allo sviluppo di un transceiver ibrido basato sulla tecnica proposta in precedenza, come proof-of-concept. Particolare attenzione viene dedicata nel mostrare come CIA sia applicabile non solo in caso di scenari di tipo CR, ma possa anche essere utilizzata in modo flessibile per incrementare le prestazioni di una generica stazione di base di tipo femto (FBS) utilizzante OFDM, tipico esempio di dispositivo a bassa potenza adottato nelle attuali reti a più livelli. Viene mostrato come un aumento dell'efficienza energetica del dispositivo sia possibile, grazie all'utilizzo di CIA. Inoltre, viene studiato l'impatto dell'allocazione di potenza effettuata dalla FBS su questo risultato viene studiato, considerando la presenza di canali caratterizzati da varie descrizioni statistiche. La tesi si conclude con la progettazione di un transceiver riconfigurabile, realizzato utilizzando un approccio di tipo software defined radio (SDR), al fine di ottenere uno strumento flessibile per realizzare esperimenti pratici che possano convalidare i precedenti risultati teorici. L'architettura proposta, in grado di trasmettere/ricevere segnali di tipo OFDM/CIA (o combinazioni di entrambi), viene infine utilizzata per testare l'efficacia di CIA nell'aumentare l'efficienza energetica di una classica trasmissione OFDM, con risultati positivi.

L’électronique flexible est actuellement considérée comme une des solutions technologiques face aux contraintes géométriques, baisse de coût et aux exigences technologiques. Cette émergence devra à terme alimenter le marché des vêtements connectés ou l’électronique implantée (in-body electronics). Toutefois, la technologie flexible n’est pas à maturité et présente quelques questions qui restent à soulever comme le choix de substrats à la fois efficace, respectueux de l’environnement et à moindre coûts, la modélisation (numérique ou analytique) d’un système ou sous-système flexible, ou l’analyse des phénomènes Electromagnétiques liés à la forme géométrique non planaire. Ce manuscrit présente le mémoire de mes travaux de thèse qui s’articulent sur la modélisation de système antennaire flexible à bas coût pour objets communicants non planaires. Le premier chapitre introduit les différents paramètres comme le facteur de qualité, les efficacités, le gain ou la polarisation, permettant d’évaluer les performances d’une antenne. Par la suite, des travaux sur différentes structures antennaires, qui se distinguent par l’emploi de substrats flexibles sont présentés et discutés afin de correctement choisir la structure antennaire la plus adéquate aux systèmes flexibles. Ce chapitre se termine par la caractérisation des substrats plastiques souples communément utilisés et qui a vu notre choix s’orienter vers les substrats Kapton HN, qui présentent le meilleur compromis efficacité-coût-robustesse. Les phénomènes EM associés à l’utilisation d’une structure d’antenne patch flexible sont analysés. Des nouvelles formules pour évaluer l’efficacité de rayonnement selon des scénarios de courbures distincts sont établies. Une méthodologie permettant une approche d’analyse et de modélisation des réseaux d’antennes patch 1×2 passif et actif est développée. En dernier lieu, deux nouvelles structures d’antennes souples et performantes en termes de bande passante et efficacités de rayonnement, sont proposées, étudiées et comparées. L’influence de la courbure de ces antennes large bande ont été étudiées en fonction d’un modèle de canal de propagation indoor. L’effet combiné du canal et de la courbure sur le gain effectif moyen des antennes est analysé et discuté
Flexible electronics is currently considered as one of the technological solutions to face up to geometric constraints, lower cost and technological requirements. This emergence will ultimately drive the market for connected clothing, implanted electronics (in-body electronics). However, the flexible technology is not mature and has some issues that remain to lift as the choice of substrates both effective, environmentally friendly and at lower costs, modeling (analytic or digital) of a system or flexible subsystem, or the analysis of electromagnetic phenomena related to non-planar geometry. This manuscript presents the memory of my PhD thesis that focuses on the modeling of flexible antenna system for low-cost non-planar communicating objects. First, the different parameters such as the quality factor, antenna efficiencies, gain or bias, for evaluating the performance of an antenna are introduced. Subsequently, research work on flexible substrate based different antenna structures is presented. The main characteristics of flexible plastic substrates commonly used are addressed. The choice towards the substrates Kapton HN, as the best compromise cost-effectiveness robustness is justified. The influence of the antenna curvature constitutes the main object of the present PhD thesis. In this way, the study on the EM phenomena associated with the use of a flexible patch antenna structure is developed. Novel analytical formulas for assessing the antenna radiation efficiency in discrete curvatures scenarios are established. In addition, a methodology providing an analysis and modeling approach to passive and active 1×2 antenna arrays is presented and validated. Finally, two new structures of flexible high performance antennas in terms of bandwidth and radiation efficiencies are designed and implemented. The Kapton-based broadband structures are based on slots antenna topology with new matching adaptation technique by the use of lumped elements. The influence of the curvature on the slot antenna prototypes are analyzed and discussed

In the last decade, cellular networks have been characterized by an ever-growing user data demand. This caused increasing capacity shortfall and coverage issues, aggravated by inefficient fixed spectrum management policies and obsolete network structures. From a practical point of view, novel technical and architectural solutions have been proposed to frame next generation cellular networks, capable of meeting the identified target performance to satisfy the user data demands. Specifically, new spectrum management policies based on the so-called dynamic spectrum access (DSA), together with hierarchical approaches to network planning, where a tier of macro base stations is underlaid with a tier of massively deployed low-power small base stations, are seen as promising candidates to achieve this scope. The resulting two-tiered network layout may improve the capacity of current networks in several ways, thanks to a better average link quality between the devices, a more efficient usage of spectrum resources and a potentially higher spatial reuse. In this thesis, we focus on the challenging problem arising when the two tiers share the transmit band, to capitalize on the available spectrum and avoid possible inefficiencies. In this case, the coexistence of the two tiers is not feasible, if suitable interference management techniques are not designed to mitigate/cancel the mutual interference generated by the active transmitters in the network. This thesis is divided in three main parts, and proposes a rather exhaustive approach to the development of new DSA and interference management techniques, to go from the theoretical basis up to a proof-of-concept development.

Ce document présente une synthèse de mes activités de recherche au cours des 10 dernières années. Recruté en septembre 2003 au laboratoire CITI, je suis venu renforcer les activités dans le domaine des communications radios, particulièrement de ce qui d'un point de vue réseau est dénommée la couche physique. Ces activités étaient jusqu'alors portées par un unique permanent (J.M. Gorce) et une doctorante. Pour être cohérent et complémentaire, j'ai dû opérer une évolution thématique pour m'intéresser aux aspects de traitement du signal et de modélisation niveau système, plus en amont de mes activités antérieures plus proches de l'électromagnétisme (même si les aspects antennes sont encore au cœur des problématiques). Mon rôle a ensuite évolué par la mise en place d'une plateforme de mesure permettant une meilleure prise en compte et validation globale des chaînes de transmissions. Cette évolution vers une vision plus globale des systèmes de transmissions m'a permis désormais de développer mon propre axe de recherche sur les aspects systèmes RF flexibles au sein du laboratoire, tout en poursuivant de multiples collaborations transverses avec mes collègues sur des aspects de radio logicielle ou encore de modélisation du canal radio.

L’objectif de ce travail est le développement de solution de détection de perte de charge d’un filtre à air qui doit être intégré à celui-ci pour un fonctionnement dans une centrale de traitement d’air (CTA). En effet, la perte de charge des filtres augmente avec la durée d’utilisation, et cette évolution a un impact non négligeable sur la consommation énergétique des ventilateurs de la CTA. Un système de mesure a été développé à partir de capteurs commerciaux connectés à un microcontrôleur, cependant ce système n’est pas perméable au flux d’air. Une solution de détection textile, basée sur le phénomène de la piézo-résistivité a été donc proposée et développée. Le substrat de base textile qui a été choisi est l’élasthanne pour ses propriétés d’élasticité, et sa capacité à se déformer sous faible contrainte. Ce matériau a été fonctionnalisé par deux techniques avec un polymère π conjugué, le poly(3,4-éthylènedioxythiophène), possédant des propriétés semi-conductrices et apportant une conductivité exploitable à un fil textile unitaire sur des longueurs de l’ordre du mètre. Ces fils textiles fonctionnalisés ont été caractérisés mécaniquement, morphologiquement, électriquement et électro-mécaniquement. Les résultats ont montré une affinité de la couche conductrice sur le substrat textile, et des procédés d’entraînement ont été établis afin d’améliorer les réponses électromécaniques pour une élongation de 5%. Pour finir, des tests préliminaires de détection sur une gaine de ventilation à l’échelle du laboratoire et sur une CTA à l’échelle industrielle ont permis de conclure que ces fils pouvaient discriminer des vitesses d’air allant de 1 à 3 m/s
The aim of this work is to develop a pressure drop detecting system, which is to be integrated onto an air filter in an air handling unit (AHU). Indeed, filter pressure drop increases with the duration of use, and theevolution has a significant impact on the energy consumption of AHU. A measurement system has been developed using commercial sensors connected to a microcontroller. But this system is not permeable to airflow. A textile sensing solution, based on the piezoresistive phenomenon, was therefore proposed and developed. The textile substrate chosen was elastane, because of its elasticity and ability to deform under low stress. This material was functionalized by two techniques with a π conjugated polymer, poly(3,4-ethylenedioxythiophene), possessing semiconducting properties and bringing exploitable conductivity to a unitary textile yarn over lengths of the order of a meter. These functionalized textile yarns were characterized mechanically, morphologically, electrically and electromechanically. The results demonstrated the affinity of the conductive layer to the textile substrate, and training procedures were established to improve electromechanical responses at 5% elongation. Finally, preliminary detection tests on a laboratory-scale ventilation duct and on an industrial-scale AHU concluded that these yarns could discriminate air velocities ranging from 1 to 3 m/s

De par les caractéristiques uniques de l'Internet des objets (IoT), telles qu'un volume massif de données, des contraintes de ressources strictes et des niveaux d'activité hétérogènes, les futures infrastructures IoT sans fil doivent intégrer des solutions d'auto-organisation intelligentes pour fonctionner efficacement dans l'environnement IoT dynamique.Dans ce contexte, cette thèse présente le développement de systèmes d'antennes intégrés reconfigurables innovants capables de s'adapter à de tels réseaux IoT sans fil dynamiques et polyvalents.Dans un premier temps, ce manuscrit de thèse traite de la conception d'antennes adaptées à une intégration dans des terminaux IoT lorsque des propriétés de rayonnement spécifiques ou des opérations multi-bandes sont nécessaires. Les structures d'antennes et les techniques d'intégration sont présentées pour les applications IoT à bande unique et multibande. Dans ce cadre, une méthodologie de conception basée sur une antenne à structure unique multi-accès et une antenne à polarisation circulaire omnidirectionnelle miniaturisée pour les applications IoT sont décrites. Ensuite, une approche basée sur les réseaux de neurones pour estimer les performances de petites antennes compte tenu des contraintes pratiques est présentée. Comme preuve de concept, le cas des antennes imprimées intégrées dans des terminaux compacts est étudié.Dans une seconde partie, la thèse porte sur le développement d'antennes reconfigurables compactes et peu gourmandes en énergie. Afin de permettre de nouvelles applications, telles que les communications portables, et d'offrir des performances supérieures dans une variété d'environnements d'intégration, une antenne flexible et reconfigurable est présentée. Pour garantir un fonctionnement fiable, les antennes flexibles doivent en effet conserver des caractéristiques radioélectriques ou de rayonnement approprié et ceci, malgré la modification de leur structure créée par la flexibilité. Le mécanisme de reconfiguration de l'antenne proposée pour les contraintes évoquées permet le décalage de sa résonance, la rendant ainsi capable de maintenir une adaptation d'impédance acceptable sur toute la bande de fonctionnement même lorsqu’elle est repliée.Une antenne compacte reconfigurable à gain et rapport avant/arrière élevés pour le filtrage spatial dans les réseaux IoT est ensuite proposée. Le mécanisme de reconfiguration est basé sur l'utilisation d'un commutateur SP4T à faible pertes d’insertion et à faible résistance, qui peut être contrôlé numériquement par un microcontrôleur, comme l'exigent les applications IoT. Une antenne à réseau parasite, avec faisceau orientable électroniquement (ESPAR, pour electronically steerable parasitic array radiator), à base d’éléments rayonnants de type fentes adaptée aux applications IoT est ensuite présentée. Le travail décrit en profondeur la procédure de conception de l'antenne, en abordant également la mise en œuvre pratique du mécanisme de reconfiguration, et se concentrant sur la réalisation du prototype et sa caractérisation expérimentale.Enfin, une méthodologie de synthèse de réseaux d'antennes parasites est proposée. Cette méthode est basée sur l'utilisation d'un algorithme de type PSO (Particle Swarm Optimizer), qui optimise de manière itérative les impédances complexes des charges connectées sur les éléments parasites jusqu'à ce que le comportement en rayonnement souhaité soit obtenu. Afin d'évaluer la capacité de la méthode à atteindre les objectifs souhaités, la méthodologie est utilisée pour optimiser la directivité, le rapport avant/arrière et le gain d’antennes à réseau parasite compactes destinées aux appareils IoT. Les valeurs des impédances de charge identifiées avec cette approche sont intégrées dans les structures d'antenne pour réaliser le réseau d'antennes parasites. La reconfiguration peut alors être simplement obtenue en réalisant une permutation circulaire des valeurs de la charge sur les éléments parasites
Because of the unique characteristics of the Internet of things (IoT), such as massive volume of data, stringent resource constraints, and heterogeneous activity levels, future wireless IoT infrastructures must integrate smart self-organizing solutions to efficiently operate in the dynamic IoT environment.Within this context, this thesis presents the development of innovative integrated reconfigurable antenna systems capable of adapting to such dynamic and multi-purposed wireless IoT networks.As a first step, the thesis covers the design of antennas suitable for integration in IoT terminals when specific radiation properties or multi-band operations are needed. Both antenna structures and integration techniques are presented for single and multi-band IoT applications. Next, a design methodology based on a multi-access single structure antenna and a miniaturized omnidirectional circularly polarized antenna for IoT applications are presented. Successively, an approach based on Neural Networks (NN) to estimate the performance of small antennas given practical constraints is presented. As proof of concept, the case of printed antennas integrated into compact terminals is considered.In the second part, the thesis focuses on the development of compact and low-power-consuming reconfigurable antennas. In order to enable new applications, such as wearable communications, and to deliver higher performance in a variety of integration environments, a flexible, reconfigurable antenna is presented. To guarantee reliable operation, flexible antennas must maintain proper electrical or radiation characteristics despite the variation of their structure given by the flexibility. Consequently, the reconfiguration mechanism of the proposed antenna allows the shift of the antenna resonance, making the antenna capable of maintaining an acceptable impedance matching over the operating band even when the antenna is folded.A compact high gain and front-to-back ratio pattern reconfigurable antenna for spatial filtering in IoT networks is then proposed. The reconfiguration mechanism is based on the use of a low-insertion, low-on resistance SP4T switch, which can be numerically controlled by a microcontroller, as required by IoT applications. Successively, a slot-based electronically steerable parasitic array radiator (ESPAR) antenna suitable for IoT applications is presented. The work describes in-depth the design procedure of the antenna, addressing the practical implementation of the reconfiguration mechanism, and focusing on the realization of the prototype and its experimental evaluation.Finally, a methodology for synthesizing parasitic antenna arrays is proposed. The method is based on the use of a Particle Swarm Optimizer (PSO), which iteratively optimizes the parasitic element loads until the desired pattern behavior is obtained. In order to assess the method's ability to address the desired goals, the methodology is used to optimize the directivity, the front-to-back ratio, and the gain of compact parasitic array antennas for IoT devices. The impedance loads values identified with this approach are integrated into the antenna structures to realize the parasitic antenna array. Reconfiguration can then simply be obtained by rotating the load's values over the parasitic elements

Future cognitive radio networks are expected to come as a disruptive technological advance in the currently saturated field of wireless communications. The idea behind cognitive radios is to think of the wireless channels as a pool of communication resources, which can be accessed on-demand by a primary licensed network or opportunistically preempted (or overlaid) by a secondary network with lower access priority. From a physical layer point of view, the primary network is ideally oblivious of the existence of a co-localized secondary networks. The latter are therefore required to autonomously explore the air in search for resource left-overs, and then to optimally exploit the available resource. The exploration and exploitation procedures, which involve multiple interacting agents, are requested to be highly reliable, fast and efficient. The objective of the thesis is to model, analyse and propose computationally efficient and close-to-optimal solutions to the above operations.Regarding the exploration phase, we first resort to the maximum entropy principle to derive communication models with many unknowns, from which we derive the optimal multi-source multi-sensor Neyman-Pearson signal sensing procedure. The latter allows for a secondary network to detect the presence of spectral left-overs. The computational complexity of the optimal approach however calls for simpler techniques, which are recollected and discussed. We then proceed to the extension of the signal sensing approach to the more advanced blind user localization, which provides further valuable information to overlay occupied spectral resources.The second part of the thesis is dedicaded to the exploitation phase, that is, the optimal sharing of available resources. To this end, we derive an (asymptotically accurate) approximated expression for the uplink ergodic sum rate of a multi-antenna multiple-access channel and propose solutions for cognitive radios to adapt rapidly to the evolution of the primary network at a minimum feedback cost for the secondary networks.

Ce projet doctoral a été réalisé au laboratoire BioMaps de l'Université Paris-Saclay et au CMPBME de l'Université Médicale de Vienne. Afin d’améliorer la valeur diagnostique de l'IRM, il est souhaitable de réduire les durées d’acquisition, d’avoir une prise en charge plus efficace des patients et une meilleure qualité des images. Dans ce but, une instrumentation portable avec un matériel optimisé permettrait de réduire le poids, d’augmenter la flexibilité et de transmettre sans fil les signaux RMN, améliorant ainsi la sensibilité, le confort, la sécurité et la facilité d'utilisation de ces dispositifs.Dans ce contexte, nous avons étudié des antennes RF souples à câbles coaxiaux basées sur le principe des résonateurs à lignes à transmission. Ces résonateurs, pouvant posséder plusieurs tours et/ou plusieurs fentes, permettent d'optimiser la taille de l’antenne RF en fonction de l'application visée. Le concept a d'abord été étudiée in silico. De nombreux prototypes ont été construits et leurs performances ont été testées sur table et en IRM à 3 et 7 T. Les antennes coaxiales ont révélé avoir des performances robustes à la déformation, ne dégradent pas le TAS et peuvent améliorer le RSB et l'efficacité de transmission lorsqu'elles sont conformées au relief de la zone imagée. En parallèle, nous avons mené une étude approfondie des technologies de transmission sans fil en IRM. Un premier prototype de communication optique sans fil pour la transmission de données de capteurs de mouvements a été réalisé et testé. Les antennes coaxiales portables que nous avons étudiées offrent une alternative intéressante aux antennes standard en raison de leur faible poids et de leur flexibilité
This PhD thesis work was conducted at the BioMaps laboratory at the Université Paris-Saclay and the Center for Medical Physics and Biomedical Engineering (CMPBME) at the Medical University of Vienna.To improve diagnostic value in MRI, shorter acquisitions, more efficient patient handling and improved image quality are needed. Wearable technology with optimized hardware reduces weight, increases flexibility, and could be wireless, thereby improving sensitivity, comfort, safety, and usability.In this work, flexible self-resonant coaxial transmission line resonators were investigated. Coaxial coils with multiple turns and gaps enable size optimization depending on the target application. The design was first studied in silico. Numerous prototypes were constructed and their performance was tested on the bench and in 3 and 7 T MRI. Coaxial coils were shown to be robust against bending, have no SAR penalty and improve SNR and transmit efficiency when form-fitted.A review of wireless MR, associated hardware developments and data transmission technology is given.An optical wireless communication module for sensor data transmission was demonstrated experimentally.Wearable coaxial coils offer an attractive alternative to standard coils due to low weight and flexibility. With wireless motion sensors diagnostic value in e.g. breast, knee, or cardiac MRI could be increased

Les films minces déposés sur des substrats flexibles ont été intensivement étudiés ces dernières années en raison de leur nombreuses applications en électronique flexible. Depuis peu, l'électronique flexible est étendu aux matériaux magnétiques conduisant ainsi au domaine émergeant de la magnéto-électronique flexible actuellement à l'avant garde des sujets de recherche de la spintronique. Ce travail de thèse est dédié à l'étude des propriétés magnéto-mécaniques de films minces magnétiques (Ni, NiFe, Co2FeAl, CoFeB, FeCuNbSi) sur des substrats flexibles. Les analyses structurales ont montré que les films de Ni et de CFA sont polycristallins non-texturés ; le CFB est amorphe. Par conséquent, les propriétés élastiques et magnéto-élastiques de ces films sont considérées comme étant isotropes. Une technique basée sur une utilisation conjointe d'essai mécanique, la résonance ferromagnétique (FMR) et la corrélation d'images numériques (CIN) a été développée pour étudier les propriétés magnéto-mécaniques de films minces sur substrats flexibles. A l'aide de cette méthode, il est possible de suivre l'évolution de l'anisotropie résiduelle omniprésente dans les films magnétiques sur substrats flexibles. Cette anisotropie est liée aux propriétés mécaniques contrastées lorsqu'on dépose un film mince rigide (grand module d'Young) sur un substrat flexible (petit module d'Young). L'effet du recuit sur les propriétés élastiques et magnéto-élastiques a été soigneusement étudié dans le film CFB validant ainsi l'intérêt porté à ses alliages pour des applications en spintronique. Enfin, la résonance ferromagnétique est employé en balayage en fréquence pour suivre la variation de la direction de l'aimantation en fonction des déformations induites par l'application de tension électrique sur l'actionneur piézoélectrique. Un retournement de 90° de la direction de l'aimantation dans le film Co2FeAl sur substrat flexible de Kapton® est observé
Thin films deposited on flexible substrates have been widely studied in the last decades due to the numerous applications in flexible electronics. Recently, flexible electronics have been extended to magnetic materials leading to the so-called emerging feld of flexible magnetoelectronics which is actually at the cutting-edge of spintronics research topics.This thesis is devoted to the study magnetomechanical properties of magnetic thin films (Ni, NiFe, Co2FeAl, CoFeB, FeCuNbSi) on flexible substrates. Structural analysis have 130 Abstracts hown that the Ni and CFA films are found to be polycrystalline with no strong preferred orientations ; the CFB film is amorphous. Consequently, the elastic and magnetoelastic properties are isotropic. For the study of the magnetomechanical properties, a set-up based on a jointly use of deformation test (bending or piezoactuation), ferromagnetic resonance (FMR) and digital image correlation (DIC) have been developped. Thanks to this method, it is possible to follow the evolution of the inescapable residual anisotropy encountered in magnetic thin films on flexible substrates under deformation and to determine the effective coefficient of magnetostriction of the films (sometimes unknown).This residual anisotropy is ascribed to contrasted mechanical strength when a sti thin film is deposited on a compliant substrate. The effect of the annealing temperature on the elastic and magnetoelastic have been studied carefully in CFB validating then theinterest on such alloys for spintronics applications. Finally, we have employed FMR inits sweep frequency mode to study the effective evolution of magnetization direction as function of the voltage-induced strains. A 90-degree magnetization rotation in Co2FeAl thin film on Kapton® polyimide substrate is observed

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 63-65).
WheelFS is a wide-area distributed file system designed to help applications cope with the challenges of sharing data over the wide-area network. A wide range of applications can use WheelFS as a storage layer because applications can control various trade-offs in WheelFS, such as consistency versus availability, using semantic cues. One key feature that many applications require from any storage system is efficient file distribution. The storage system needs to be able to serve files quickly, even large or popular ones, and allow users and applications to quickly browse files. Wide-area links with high latency and low throughput make achieving these goals difficult for most distributed storage systems. This thesis explores using pre fetching, a traditional file system optimization technique, in wide-area file systems for more efficient file distribution. This thesis focuses on Tread, a pref etcher for WheelFS. Tread includes several types of pre fetching to improve the performance of reading files and directories in WheelFS: read-ahead pre fetching, whole file prefetching, directory prefetching and a prefetching optimization for WheelFS's built-in cooperative caching. To makes the best use of scarce wide-area resources, Tread adaptively rate-limits prefetching and gives applications control over what and how prefetching is done using WheelFS's semantic cues. Experiments show that Tread can reduce the time to read a 10MB file in WheelFS by 40% and the time to list a directory with 100 entries by more than 80%.
(cont.) In addition, experiments on Planetlab show that using prefetching with cooperative caching to distribute a 10MB file to 270 clients reduces the average latency for each client to read the file by almost 45%.
by Irene Y. Zhang.
M.Eng.

Gli ossidi amorfi semiconduttori (AOS) sono nuovi candidati per l’elettronica flessibile e su grandi aree: grazie ai loro legami prevalentemente ionici hanno una mobilità relativamente alta (µ > 10cm^2/Vs) anche nella fase amorfa. Transistor a film sottile (TFT) basati sugli AOS saranno quindi più performanti di tecnologie a base di a-Si e più economici di quelle a base di silicio policristallino. Essendo amorfi, possono essere depositati a basse temperature e su substrati polimerici, caratteristica chiave per l’elettronica flessibile e su grandi aree. Per questa tesi, diversi TFT sono stati fabbricati e caratterizzati nei laboratori del CENIMAT all’Università Nova di Lisbona sotto la supervisione del Prof. P. Barquinha. Questi dispositivi sono composti di contatti in molibdeno, un canale semiconduttivo di ossido di zinco, gallio e indio (IGZO) e un dielettrico composto da 7 strati alternati di SiO2 e SiO2+Ta2O5. Tutti i dispositivi sono stati depositati mediante sputtering su sostrati flessibili (fogli di PEN). Le misure tensione-corrente mostrano che i dispositivi mantengono alte mobilità (decine di 10cm^2/Vs) anche quando fabbricati a temperature inferiori a 200°C. Si è analizzato il funzionamento dei dispositivi come fototransistor rilevando la risposta alla luce ultravioletta e in particolare la loro responsività e spostamento della tensione di soglia in funzione della lunghezza d’onda incidente. Questi risultati consentono di formulare ipotesi sul comportamento dei dispositivi alla scala microscopica. In particolare, indicano che i) la mobilità del canale non è influenzata dall’illuminazione, ii) sia l'IGZO sia il Ta2O5 contribuiscono al processo di fotoconduttività e iii) il processo di fotogenerazione non è adiabatico. La tesi contiene inoltre una descrizione del processo di ricombinazione e presenta un’applicazione pratica di tali dispositivi in un circuito per RFID. Infine, esplora la possibilità di migliorarne la flessibilità e le prestazioni.

Il est attendu que les radios flexibles constituent un tournant technologique majeur dans le domaine des communications sans fil. Le point de vue adopté en radios flexibles est de considérer les canaux de communication comme un ensemble de ressources qui peuvent être accédées sur demande par un réseau primaire sous licence ou de manière opportuniste par un réseau secondaire à plus faible priorité. Pour la couche physique, le réseau primaire n'a idéalement aucune information sur l'existence d'un ou plusieurs réseaux secondaires, de sorte que ces derniers doivent explorer l'environnement aérien de manière autonome à la recherche d'opportunités d'accès au canal et exploiter ces ressources de manière optimale au sein du réseau secondaire. Les phases d'exploration et d'exploitation, qui impliquent la gestion de nombreux agents, doivent être très fiables, rapides et efficaces. L'objectif du présent rapport est de modéliser, d'analyser et de proposer des solutions efficaces et quasi optimales pour ces dernières opérations. En particulier, en ce qui concerne la phase d'exploration, nous nous appuierons sur le principe d'entropie maximale pour modéliser des canaux de communication, pour lesquels nous calculerons le test optimal de Neyman-Pearson de détection de plusieurs sources via un réseau de capteurs. Cette procédure permet à un réseau secondaire d'établir la présence de ressources spectrales disponibles. La complexité calculatoire de l'approche optimale appelle cependant la mise en place de méthodes moins onéreuses, que nous rappellerons et discuterons. Nous étendrons alors le test de détection en l'estimation aveugle de la position de sources multiples, qui permet l'acquisition d'informations détaillées sur les ressources spectrales disponibles. Le dernier chapitre d'importance sera consacré à la phase d'exploitation optimale des ressources au niveau du réseau secondaire. Pour ce faire, nous obtiendrons une approximation fine du débit ergodique d'un canal multi-antennes à accès multiples et proposerons des solutions peu coûteuses en termes de feedback afin que les réseaux secondaires s'adaptent rapidement aux évolutions rapides du réseau primaire. Les outils mathématiques et algorithmes proposés dans ce rapport proviennent essentiellement de récents progrès en théorie des matrices aléatoires, et plus spécifiquement de l'étude de matrices aléatoires à grandes dimensions et à entrées statistiquement indépendantes. Une introduction précise des concepts principaux ainsi que des résultats récents requis à la compréhension complète du présent document sont également proposés.

L’objectif de ces travaux est d’étudier et de développer des cellules solaires à base de couches minces de CIGS élaborées sur un substrat innovant : le verre ultra-fin. Ce matériau possède des propriétés avantageuses, liées notamment à sa résistance aux températures élevées, à sa légèreté, à son aptitude à bloquer l’humidité, à sa transparence et à une certaine flexibilité mécanique. Nous avons ici cherché à exploiter ces propriétés pour la fabrication de cellules CIGS légères et conformables. D’abord, nous montrons la faisabilité de cellules CIGS sur des substrats en verre ultra-fin de 100 mm d’épaisseur. Nous obtenons un rendement de 12,1 % en utilisant une électrode arrière en bicouche composée d’une couche de Mo pure et d’une couche contenant du sodium, ce qui constitue le record actuel pour la technologie CIGS sur verre ultra-fin. Nous montrons ensuite que les performances des cellules peuvent se détériorer sous l’effet de flexions mécaniques répétées avec un rayon de courbure de 5 cm, en partie en raison de la formation de fissures dans les cellules. Nous présentons ensuite une étude sur les propriétés mécaniques du Mo et du CIGS, réalisée à partir d’essais de nanoindentation. La dureté et le module de Young de ces deux couches sont reportés ainsi que, pour la première fois, la ténacité et les contraintes résiduelles du CIGS. Ces résultats sont ensuite utilisés pour calculer les contraintes générées dans le CIGS lors de la flexion des cellules. Enfin, nous proposons une structure bi-verre optimisée pour limiter les contraintes dans le CIGS en flexion
The goal of this work is to study and to develop CIGS thin-film solar cells on an innovative substrate: the ultra-thin glass. This material has advantageous properties, mainly attributed to its high temperature resistance, its lightweight, its barrier property against moisture, its transparency and its mechanical flexibility. Here we tried to use these properties for the fabrication of lightweight and conformable CIGS solar cells. First, we demonstrate the feasibility of CIGS solar cells on 100 mm-thick ultra-thin glass substrates. We reached 12.1 % efficiency by using a bilayer back contact consisting of a pure Mo layer and a sodium doped Mo layer, which is up to now the record efficiency for CIGS solar cells on ultra-thin glass substrate. Then we show that solar cell performances can deteriorate under cyclic bending fatigue conditions with a radius of curvature of 5 cm. This is partially explained by the formation of cracks in the cells. Then, we report on the mechanical properties of the Mo and the CIGS layers measured by nanoindentation. The hardness and the Young’s modulus of each layer is given and, for the first time, the toughness and the residual stresses of the CIGS. These results are then used to calculate the CIGS internal stresses when the cells are bent. Finaly, we propose a glass-glass structure optimized to lower the CIGS internal stresses under bending

Cadmium Telluride (CdTe) is a leading thin film photovoltaic (PV) material due to its near ideal bandgap of 1.45 eV and its high optical absorption coefficient. The typical CdTe thin film solar cell is of the superstrate configuration where a window layer (CdS), the absorber (CdTe) and a back contact are deposited onto glass coated with a transparent electrode. Substrate CdTe solar cells where the above listed films are deposited in reverse are not common. In this study substrate CdTe solar cells are fabricated on flexible foils. The properties of the Molybdenum back contact, Zinc Telluride (ZnTe) interlayer and CdTe absorber on the flexible foils were studied and characterized using X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM). Substrate curvature and film flaking was observed during the fabrication as a result of differences in thermal expansion coefficients between the substrate and the deposited films, and also due to impurity diffusion from the foil into the film stack. In order to overcome this problem diffusion barriers where used to eliminate contamination. Silicon dioxide (SiO2), silicon nitride (Si3N4) and molybdenum nitride (MoxNy) were used as such barriers. Electrical characterization of completed devices was carried out by Current-Voltage (J-V), Capacitance-Voltage (C-V) and Spectral Response (SR) measurements. Roll-over was observed in the first quadrant of J-V curves indicating the existence of a back barrier due to a Schottky back contact. The formation of non-rectifying contact to p-CdTe thin-film is one of the major and critical challenges associated with the fabrication of efficient and stable solar cells. Several materials (ZnTe, Cu, Cu2Te, and Te) were studied as potential candidates for the formation of an effective back contact.

Le travail de cette thèse porte sur le développement de transistors en couche mince (Thin Film Transistors, TFTs) à base de silicium microcristallin fabriqués sur un substrat flexible à très basse température (T< 180 °C). La première partie de ce travail a consisté à étudier la stabilité électrique de ces TFTs. L'étude de la stabilité électrique des TFTs de type N fabriqués sur verre a montré que ces TFTs sont assez stables, la tension de seuil VTH ne se décale que de 1.2 V au bout de 4 heures de stress sous une tension de grille VGSstress= +50V et à une température T=50 °C. L'instabilité électrique de ces TFTs est principalement causée par le piégeage des porteurs dans l'isolant de grille. La deuxième étape de ce travail s'est concentrée sur l'étude du comportement de ces TFTs sous déformation mécanique. Ces TFTs sont soumis à un stress mécanique en tension et en compression. Le rayon de courbure minimum que les TFTs pouvaient supporter est r=1.5 mm en tension et en compression. La limitation de la déformation mécanique de ces TFTs est principalement due à la contrainte mécanique du nitrure de silicium utilisé comme isolant de grille des TFTs. Autrement dit, ces TFTs sont mécaniquement fiables et présentes une faible variation du courant ION, de l'ordre de 1%, même après 200 cycles de déformation mécanique. Ces résultats obtenus laissent entrevoir la possibilité de concevoir une électronique flexible pouvant être pliée en 2. Enfin, les TFTs sont fabriqués avec différents isolants de grille afin d'augmenter la mobilité d'effet de champ. Malheureusement, aucun isolant de grille utilisé dans ces études n'a permis d'augmenter la mobilité d'effet de champ sans dégrader la stabilité électrique des TFTs. Des études plus détaillées et des optimisations complémentaires sur ces isolants de grille sont nécessaires
This work deals with the development of microcrystalline silicon thin film transistors (TFTs) fabricated on flexible substrate at low temperature (T=180 °C). The first step of this work consists in studying the electrical stability of TFTs. The N-type TFTs fabricated on glass substrate are electrically stable under gate bias stress VGStress= +50V at T=50 °C. The threshold voltage shift (ΔVTH) was only 1.2 V during 4 hours. This electrical instability of TFTs is mainly due to carrier trapping inside the silicon nitride gate insulator. The second step of this work lies in the study of the mechanical behavior of the TFTs. Both tensile and compressive strains were applied on TFTs. The minimum curvature radius is r=1.5 mm for both tension and compression. The main limitation of TFTs comes from the mechanical strain εlimit of silicon nitride used as gate insulator of TFTs. Also, these TFTs are mechanically reliable: the variation of ION current was only 1% after 200 cycles mechanical bending. These results obtained open the way to the development of flexible electronics that can be folded in half.Finally, TFTs have been fabricated using different gate insulators in order to improve the mobility. Unfortunately, all the gate insulators used couldn’t improve mobility without sacrificing electrical stability of TFT. More detailed studies and complementary optimization of these gate insulators are necessary

The aim of this thesis is to implement flexible interpolators and decimators onField Programmable Gate Array (FPGA). Interpolators and decimators of differentwordlengths (WL) are implemented in VHDL. The Farrow structure is usedfor the realization of the polyphase components of the interpolation/decimationfilters. A fixed set of subfilters and adjustable fractional-delay multiplier valuesof the Farrow structure give different linear-phase finite-length impulse response(FIR) lowpass filters. An FIR filter is designed in such a way that it can be implementedfor different wordlengths (8-bit, 12-bit, 16-bit). Fixed-point representationis used for representing the fractional-delay multiplier values in the Farrow structure. To perform the fixed-point operations in VHDL, a package called fixed pointpackage [1] is used. A 8-bit, 12-bit, and 16-bit interpolator are implemented and their performancesare verified. The designs are compiled in Quartus-II CAD tool for timing analysisand for logical registers usage. The designs are synthesised by selecting Cyclone IVGX family and EP4X30CF23C6 device. The wordlength issues while implementingthe interpolators and decimators are discussed. Truncation of bits is required inorder to reduce the output wordlength of the interpolator and decimator.

Cette thèse traite de l'évaluation des performances d'un atelier flexible en présence de pannes. Nous décrivons deux modèles différents d’ateliers flexibles dans lesquels les stations de travail sont placées autour d'un convoyeur formé de nombre fixe de cellules qui transporte les pièces à usiner et qui tourne à vitesse constante. L'atelier se compose de deux parties : l'une située entre l'entrée du système et sa sortie l'autre située entre la sortie de l'atelier et son entrée. Dans le premier modèle, les pièces peuvent demander de service plusieurs fois à la même station. Nous donnons la probabilité de sortie pour les pièces ayant terminé leur service. Dans le deuxième modèle, les pièces sont testées pour le passage dans la deuxième partie de l'atelier et elles ne peuvent demander le service qu'une seule fois à la même station. Dans les deux modèles, le convoyeur est de capacité limitée, les files d'attente sont de capacité illimitée. Nous étudions ces modèles en utilisant deux approches : l'une est la théorie de files d'attente et l'autre est la simulation avec QNAP2. Nous concluons ce travail en comparant les résultats contenus avec des deux approches
In this thesis we discuss the performance of flexible manufacturing systems subject to failures. We describe two models of manufacturing systems with n stations, and with a limited conveyor belt moving at constant speed and with unlimited queue size. The conveyor belt is composed of two parts. The first part is between entry point and the exit point of the system; and the second is between exit point and entry point of the system. In the first model the pieces may leave the system with a given probability and they may request service from the same station several times. In the second model the pieces are tested before going to the second part of the conveyor and they may request only once service from any station. Each model has being studied with two differents approaches: an analytical model based on queueing theory and a simulation model using the QNAP2 package
Modèle d'atelier flexible utilisant la théorie des files d'attente et tenant compte des pannes

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged student-submitted from PDF version of thesis.
Includes bibliographical references (pages 257-270).
6,13-Bis(triisopropylsilylethynyl)pentacene and pentacene high-voltage organic thin film transistors (HVOTFTs) were fabricated on solid and flexible substrates via a low temperature (< 120 °C) solution-processed and vacuum-deposited fabrication methods, achieving breakdown voltages and on/off current ratios beyond -550 V and 10⁶ A/A, respectively, a first of its kind. The HVOTFT design was based on a dual channel architecture, where a gated region enabled FET capabilities and an offset region accommodated the high-voltage. An HVOTFT capable of driving high-voltages ([V[lower case DS]] > 100 V) while being controlled by a relatively low gate-to-source voltage ([V[lower case GS]] < 50 V) will enable new applications on arbitrary and flexible substrates, such as large electrostatic MEMS actuators, electroactive polymers, novel displays, field-emitter arrays for digital x-ray imaging as well as photovoltaic systems on glass. A high-k dielectric Bi₁.₅Zn₁Nb₁.₅O₇ and a low-k organic dielectric parylene-C were incorporated into the HVOTFT process to improve threshold voltage and mobility. Field plate designs and self-assembled monolayers were also explored to enhance the HVOTFT's electrical characteristics by directly controlling the charge carrier distribution within the channel or by improving the charge carrier injection into the organic semiconductor. Moreover, a self-shearing drop cast deposition method has been employed for the HVOTFT for the first time, growing large and highly oriented organic semiconductor grains. Solution-processing will enable room-temperature, air ambient and large-area depositions techniques, reducing fabrication overhead. Furthermore, a self-aligned solution-processing method based on surface energy engineering was developed with self-assembled monolayers to create pre-patterned organic semiconductor channels without the need for etching.
by Andy Shih.
Ph. D.

2D molybdenum disulfide (MoS₂) gives a new inspiration for the field of nanoelectronics, photovoltaics, and sensorics. However, the most common processing technology, e.g., liquid‐phase based scalable exfoliation used for device fabrication, leads to the number of shortcomings that impede their large area production and integration. Major challenges are associated with the small size and low concentration of MoS₂ flakes, as well as insufficient control over their physical properties, e.g., internal heterogeneity of the metallic and semiconducting phases. Here it is demonstrated that large semiconducting MoS₂ sheets (with dimensions up to 50 µm) can be obtained by a facile cathodic exfoliation approach in nonaqueous electrolyte. The synthetic process avoids surface oxidation thus preserving the MoS₂ sheets with intact crystalline structure. It is further demonstrated at the proof‐of‐concept level, a solution‐processed large area (60 × 60 µm) flexible Ebola biosensor, based on a MoS₂ thin film (6 µm thickness) fabricated via restacking of the multiple flakes on the polyimide substrate. The experimental results reveal a low detection limit (in femtomolar–picomolar range) of the fabricated sensor devices. The presented exfoliation method opens up new opportunities for fabrication of large arrays of multifunctional biomedical devices based on novel 2D materials.

This thesis describes the electrical behaviour of solution-processed zinc oxide thin film transistors (ZnO TFTs) fabricated at low temperature. First, the electrical properties of solution-processed ZnO films are reported. Spin-coated ZnO films annealed at 150 °C exhibit significant sensitivity to the ambient environment. However, their stability can be improved by hydrogen plasma treatment. Zinc oxide TFTs (channel width/length = 4000/200 μm) fabricated by chemical spray pyrolysis at the low process temperature of 140 °C are investigated. The resulting transistors exhibit a saturation mobility of 2 cm2/Vs measured in air; this value is reduced to 0.5 cm2/Vs under vacuum. The effect of hydrogen plasma treatment on spin-coated ZnO TFTs is then studied. The electrical characteristics of untreated TFTs exhibit large hysteresis and a positive threshold voltage shift on repeated measurements. These effects are reduced by the hydrogen plasma and an increase in carrier mobility is observed. In a further investigation, a solution-processed silicon dioxide gate insulator for application in the TFTs is used; a perhydropolysilazane (PHPS) precursor is spin-coated with subsequent thermal treatment to form the SiO2 layer. Exposure to oxygen plasma leads to an acceleration of the conversion reaction, resulting in good insulating properties (leakage current density of ~10-7 A/cm2) and TFT performance (channel width/length = 1000/50 μm, carrier mobility of 3.2 cm2/Vs, an on/off ratio of ~107, a threshold voltage of -1.3 V and a subthreshold swing of 0.2 V/decade). Finally, a photolithographic process is introduced for the fabrication of ‘short’ channel solution-processed ZnO TFTs. Optimum processing conditions are established and used for the fabrication of transistors having various channel dimensions. Devices with a minimum channel length of 5 μm possessed a mobility of 1.5 x 10-2 cm2/Vs, on/off ratio of 106 and good contact between the S/D electrodes and the semiconductor. The relatively low mobility could originate from gate insulator roughness caused by the photolithographic processes.

碩士
國立交通大學
材料科學與工程學系
100
Moisture and oxygen permeation barrier technology become critical in achieving the required lifetime reliability of flexible devices such as flexible organic light-emitting diode (FOLED) and flexible solar cells. To date, thin-film encapsulation using multilayered organic/inorganic barriers on flexible polymer substrate is the most promising. However, there are still several challenging issues such as defects and cost. This study first established a water-vapor-transmission-rate (WVTR) measurement system with a high sensitivity (~10-5 g/m2/day). Next we developed a high-performance moisture barrier (8x10-5 g/m2/day) on flexible PET substrate. This is achieved by an alternating organic barrier (plasma polymerized polystyrene, PPS)/inorganic barrier, silicon carbonitride (SiCxNy) multi-layered structure, using plasma-enhanced chemical vapor deposition (PECVD) at room temperature and without breaking the vacuum, based on 1,3,5-trimethyl-1,3,5-trivinylcyclo-trisilazane (VSZ) and styrene precursor, respectively. The effects of barrier materials, their thicknesses, and the numbers of layer on WVTR, and the controlling mechanism were also investigated. A single SiCxNy barrier layer (100 nm) effectively reduces the WVTR of a PET film from 3 g/m2/day to 5×10-2 g/m2/day. Multi-layered moisture barrier structures based on triple SiCxNy barrier layers or SiCxNy/PPS/SiCxNy (100 nm each) can further reduce WVTR to 6×10-3 and 8×10-3 g/m2/day, respectively. In summary, multi-layered barrier can effectively reduce WVTR as compared to single layer at the same total thickness. Also, moisture barrier materials consisting of alternating SiCxNy and PPS multi-layered stack (4-pair with a total thickness of 0.8 ?慆) can effectively reduce WVTR down to 8×10-5 g/m2/day. Through the pinhole decoration by Ni electro-deposition, the mechanism of high-performance WVTR in a multilayered barrier can be attributed to the much increase in diffusion paths due to a reduction of pinhole defects healed by the alternating deposited, upper layer.

Tese de Doutoramento Programa Doutoral em Engenharia Electrónica e Computadores.
Rechargeable energy storage relies mainly on lithium-ion battery technology, the same that supports most of the mobile world. This technology is under research by many groups around the world and is still considered the best way to store electrical energy from intermittent power sources. However, battery technology is limiting the evolution of many integrated electronics, especially in wearable applications; improvements in terms of energy density, higher number of life cycles, flexibility and safety are still needed. In thin-film batteries, the selection, the design structure, fabrication process and characterization of materials as well as film deposition techniques play an important role in the maximization of the battery performance, durability and reproducibility. This thesis contributes to battery technology in several ways. The use of a typical flexible substrate (Kapton®, by Dupont™) while fabricating all battery materials in the same chamber, including barrier and encapsulation materials, excluding the necessity for extra vacuum and glove-box chambers, was researched. Using only safe solid-state materials, on which no leakage or explosions can occur and replacing metallic lithium (Li) anode for a much more “friendly” material in terms of fabrication and battery cycling, battery energy density benefits. The thin-film lithium phosphorous oxynitride (LiPON) electrolyte is required to have high ionic conductivity, a negligible electrical conductivity and to be stable in contact with the anode and cathode electrodes. LiPON electrolyte was deposited by RF sputtering at different experimental conditions. The highest ionic conductivity of 1 x 10-6 S/cm was measured at ambient temperature of 35 ⁰C for a film deposited with power supply of 150 W, 20 sccm of nitrogen (N2) and a deposition pressure of 3 x 10-4 mbar. Samples with a silicon nitride (Si3N4) barrier layer, a titanium (Ti) adhesion layer and a platinum (Pt) cathode current collector layer (Kapton/Si3N4/Ti/Pt) were prepared for flexibility experiments of Kapton® substrate. Si3N4 Li barrier layer was deposited by RF sputtering deposition technique with an electric resistivity of 9.51 x 1011 Ωcm and a mean breakdown field of 1.67 MV/cm. Thin-films continued attached to the substrate after several bends. Lithium cobalt oxide (LiCoO2) cathode was deposited on top of Kapton/Si3N4/Ti/Pt structure. After LiCoO2 deposition, annealing at 400 ⁰C was performed during 1 hour at different atmospheres (vacuum and air). The films annealed in air atmosphere presented higher crystallinity, especially in the plane (101), the orientation required for batteries with improved performance and durability. Cathode LiCoO2 films were deposited by RF sputtering with a 120 W power supply, pressure of 6 x 10-3 mbar and 17/3 sccm of Ar/O2 gases, respectively. A thin-film flexible Li battery and a thin-film flexible Li-ion battery were successfully fabricated using only physical vapour deposition (PVD) techniques. The anodes of metallic Li (for Li-battery) and germanium (Ge) (for Li-ion battery) were deposited 3 μm thick by thermal evaporation and 300 nm thick by e-beam, respectively. A well-organized battery structure with smooth interfaces and good adhesion was observed by scanning electron microscope (SEM) analysis. A self-discharge was measured and related to a possible thinner electrolyte in some area between the cathode and the anode on both fabricated batteries. A low potential and retention fading along charge/discharge cycles were also measured and related to an amorphous LiCoO2. Despite the low capacity presented by the two batteries, an improvement when the Li anode was changed to Ge is evident (0.35 nAh/cm2 with Li anode, to 46 nAh/cm2 with Ge anode). A battery encapsulation with three sputtered layers: lithium phosphorous oxide (LiPO), LiPON and Si3N4, each 20 nm thick, was fabricated. After these depositions and at atmospheric conditions, an epoxy was applied on the PVD multilayer to complete the encapsulation for long term protection. Research indicates it is possible to fabricate flexible thin-film Li batteries on Kapton® substrate using only PVD deposition techniques, avoiding the necessity of extra vacuum and glove-box chambers.
O armazenamento de energia elétrica recarregável baseia-se principalmente na tecnologia de baterias de iões de lítio, a mesma que suporta a maior parte do mundo móvel. Esta tecnologia está sob investigação por muitos grupos ao redor do mundo e ainda é considerada a melhor forma de armazenar energia elétrica a partir de fontes de energia intermitentes. No entanto, a tecnologia das baterias está a limitar a evolução da eletrônica integrada, especialmente em aplicações portáteis; melhorias em termos de densidade de energia, maior número de ciclos de carga/descarga, flexibilidade e segurança ainda são necessários. Em baterias de filme fino, a seleção, a estrutura, o processo de fabricação e caracterização dos materiais, bem como as técnicas de deposição dos filmes, desempenham um papel importante na maximização do desempenho, durabilidade e reprodutibilidade da bateria. Esta tese contribui para a tecnologia das baterias de várias maneiras. A utilização de um substrato flexível típico (Kapton®, por Dupont™), enquanto todos os materiais da bateria são fabricados na mesma câmara, incluindo os materiais para encapsulamento e barreira, excluindo a necessidade de câmaras de vácuo e câmaras de luvas extra, foi investigada. Utilizando apenas materiais seguros e em estado sólido, em que derramamentos ou explosões não podem ocorrer, e substituindo o ânodo de lítio (Li) metálico por um material muito mais "amigável" em termos de fabricação e de carga/descarga da bateria, a densidade de energia da bateria beneficia. O eletrólito de filme fino de oxinitreto fosfato de lítio (LiPON) deve ter elevada condutividade iónica, condutividade elétrica negligenciável e ser estável em contacto com o ânodo e cátodo. O LiPON foi depositado por pulverização catódica de radio frequência (RF sputtering) em diferentes condições experimentais. A maior condutividade iónica (1 x 10-6 S/cm) foi medida à temperatura ambiente de 35 ⁰C para um filme depositado com 150 W na fonte, 20 sccm de azoto (N2) e 3 x 10-4 mbar de pressão durante a deposição. Amostras com uma camada de barreira, nitreto de silício (Si3N4), uma camada de adesão, titânio (Ti), e uma camada de coletor de corrente do cátodo, platina (Pt), (Kapton/Si3N4/Ti/Pt) foram preparadas para as experiencias de flexibilidade do substrato de Kapton. A camada de barreira aos iões de lítio, Si3N4, foi depositada por RF sputtering com uma resistividade elétrica de 9.51 x 1011 Ωcm e uma tensão média de rotura de 1.67 MV/cm. Os filmes finos continuaram em cima do substrato após várias dobragens do mesmo. O cátodo de óxido de lítio cobalto (LiCoO2) foi depositado no topo da estrutura Kapton/Si3N4/Ti/Pt. Após a deposição do LiCoO2, um recozimento a 400 ⁰C foi realizado durante 1 hora a diferentes atmosferas (vácuo e ar). Os filmes recozidos em atmosfera de ar apresentaram maior cristalinidade, especialmente no plano (101), a orientação necessária para baterias com melhor desempenho e durabilidade. Os filmes de LiCoO2 foram depositados por RF sputtering com 120 W na fonte, 6 x 10-3 mbar de pressão e 17/3 sccm de gases Ar/O2, respetivamente. Uma bateria de Li e uma bateria de Li-ion, flexíveis e em filme fino, foram fabricadas com sucesso usando apenas técnicas de PVD. Os ânodos de Li metálico (para a bateria de Li) e germânio (Ge) (para a bateria de Li-ion) foram depositados com 3 μm de espessura por evaporação térmica e 300 nm de espessura por feixe de eletrões, respetivamente. Uma estrutura bem organizada, com interfaces regulares e boa adesão entre os filmes foram observados na bateria por microscopia eletrónica de varrimento (SEM). Auto-descarga foi medida e relacionada com uma área mais fina entre o eletrólito e o cátodo em ambas as baterias fabricadas. Um baixo potencial e um enfraquecimento na retenção de carga ao longo dos ciclos de carga/descarga também foram medidos e relacionados com o facto de o LiCoO2 ser amorfo. Apesar da baixa capacidade apresentada pelas duas baterias, uma melhoria quando o ânodo de Li foi alterado para o ânodo de Ge é evidente (0.35 nAh/cm2 com ânodo de Li e 46 nAh/cm2 com ânodo de Ge). Um encapsulamento para a bateria com três camadas: óxido fosfato de lítio (LiPO), LiPON e Si3N4, cada uma com 20 nm de espessura, foi fabricado por RF sputtering. Depois destas deposições e em condições atmosféricas, uma epóxi foi aplicada sobre a multicamada fabricada por PVD, para completar o encapsulamento para a proteção a longo prazo. A investigação indica que é possível fabricar baterias de Li em filme fino no substrato flexível Kapton®, utilizando apenas técnicas de deposição por PVD, evitando assim a necessidade de câmaras de vácuo e de luvas suplementares.
Fundação para a Ciência e a Tecnologia (FCT) SFRH/BD/78217/2011.
CRUP AI TC-09_14 and KNMF 2014-011-003169.

碩士
國立中山大學
材料科學研究所
96
In this research, CuInSe2 thin film is grown at 350℃ low temperature by photo-assisted co-evaporation system to fabricate PI (polyimide) substrate flexible thin film solar cells. The low temperature growing CuInSe2 is analyzed by raman spectroscopy. Besides, sputtering Mo thin film on PI and CIS/Mo/PI contact properties are also researched for device fabrication. By studying the Ar pressure and Mo internal stress relationship during the deposition, the Mo layer has been fabricated with both low resistivity and good adhesion. The sheet resistance of Mo layer is 1.95 Ω/□ and shows ohmic contact with CuInSe2 at temperature below 350℃. Raman spectroscopy shows that photo-assisted CuInSe2 has stronger and thinner A1 peak than which without light. Two-stage growing can help eliminating Cu2Se and background signals further. CA structure vibration modes are involved in the asymmetric A1 peak broadening. The SLG/Mo/CIS/CdS/ZnO:Al/Al structured device has open voltage, Voc = 0.320 V, short cut current, Isc = 3.61 mA, and solar cell fill factor, FF = 49.8 %. On the other hand, PI/Mo/CIS/CdS/ZnO:Al/Al structured device has open voltage, Voc = 0.318 V, short cut current, Isc = 2.71 mA, and solar cell fill factor, FF = 39.0 %。

碩士
聖約翰科技大學
自動化及機電整合研究所
101
CIGS has become one of the most important materials of thin film solar cells because of its high absorption efficiency. This work investigates the processing parameters of flexible CIGS solar cells. The Mo conducting films is sputtered on stainless steel shells, and utilizes CuGa and In targets to sputter CIG precursor films on the Mo/stainless steel substrates. Then, combines the CIGS absorption layers with high temperature selenization. The surface roughness, micro structure, composition, crystallization, residual stress, and conductivity of the CIGS are characterized by the 3D profiler, scanning electronic microscope, energy dispersive spectrometer, X-ray diffraction machine, and Hall effects meter. Various precursor CuGa/In ratios are studied. The results show that the CIGS fabricated with sputtering 30 min In first, then sputtering CuGa and keeping CuGa/In=1/2 behaves the best performance. It is because that deposition In precursor at first can prevent it loses during high temperature selenization and improves the crystallization and conductivity of CIGS.

碩士
國立彰化師範大學
光電科技研究所
102
In this thesis, we study the characteristics of flexible organic thin film transistors and its application to gas sensor. In first section, we have fabricated the pentacene, one of the most popular organic semiconductors, thin film transistors with/without buffer layer on PET substrate. With suitable buffer layer on PET substrate, the transistors’ performance could be dramatically raised, such as the field effect mobility was raised orders and achieved an average of 1 cm2/vs. Next, the pentacene transistors were measured under compressive and tensile status with different curved radius. At flat condition, the device has a mobility of 0.88 cm2/vs, then it downgraded to 0.74 cm2/vs after tensile stress at curved radius 2.5 cm. However the mobility was enhanced slightly at compressive status with curved radius 1.5 cm. Those phenomena could be owing to the tiny rearrange of pentacene molecule at different curved status and would be detail discussed in thesis. Finally, a gas sensor with above mentioned pentacene transistor structure was measured in ambient gas, nitrogen gas, oxygen gas and water vapor, respectively. It shows that pentacene was sensitive to oxygen and water, but not nitrogen. Pentacen transistors also need a longer recovered time for exposure to water, 27 sec, than the recovered time for exposure to oxygen, 3.3 sec.

abstract: A low temperature amorphous oxide thin film transistor (TFT) backplane technology for flexible organic light emitting diode (OLED) displays has been developed to create 4.1-in. diagonal backplanes. The critical steps in the evolution of the backplane process include the qualification and optimization of the low temperature (200 °C) metal oxide process, the stability of the devices under forward and reverse bias stress, the transfer of the process to flexible plastic substrates, and the fabrication of white organic light emitting diode (OLED) displays. Mixed oxide semiconductor thin film transistors (TFTs) on flexible plastic substrates typically suffer from performance and stability issues related to the maximum processing temperature limitation of the polymer. A novel device architecture based upon a dual active layer enables significant improvements in both the performance and stability. Devices are directly fabricated below 200 ºC on a polyethylene naphthalate (PEN) substrate using mixed metal oxides of either zinc indium oxide (ZIO) or indium gallium zinc oxide (IGZO) as the active semiconductor. The dual active layer architecture allows for adjustment in the saturation mobility and threshold voltage stability without the requirement of high temperature annealing, which is not compatible with flexible colorless plastic substrates like PEN. The device performance and stability is strongly dependent upon the composition of the mixed metal oxide; this dependency provides a simple route to improving the threshold voltage stability and drive performance. By switching from a single to a dual active layer, the saturation mobility increases from 1.2 cm2/V-s to 18.0 cm2/V-s, while the rate of the threshold voltage shift decreases by an order of magnitude. This approach could assist in enabling the production of devices on flexible substrates using amorphous oxide semiconductors.
Dissertation/Thesis
M.S. Chemical Engineering 2011

碩士
義守大學
電子工程學系碩士班
98
The capacitors were fabricated on flexible substrates by using spin coating process various ratio of high dielectric constant ceramic materials were mixed with low dielectric constant resins by a triple roller. The effect of high permittivity materials on the dielectric properties were investigated. In addition, conductive materials were added in to the matrix to increase dielectric constant of composites. Dielectric properties of the composite depend on the amount of high permittivity ceramics and higher amount of ceramics result in higher dielectric constant. The dielectric constant of 25wt% al added 50wt% BaTiO3+50 wt%ITK5517 specimen is 127 measured at 1kHz and dissipation factor is 0.05. The addition of conductive Al particles greatly enhance dielectric constant of the composites.

碩士
國立宜蘭大學
機械與機電工程學系碩士班
101
VDF, a piezoelectric polymer, is suitable for flexible devices because of its flexibility and lightweight. In this article, the authors adopt commercial PVDF film to make a film loudspeaker. The proposed film loudspeaker is a sandwiched membrane structure which contains a PVDF film sandwiched in between two silver electrode-layers. An audio signal is applied to the PVDF film, which responds by the mechanical deflection in proportion to the voltage applied across the PVDF film, thus converting electrical energy into mechanical vibration. Therefore, the coupled electromechanical characteristic of the compound membrane dominates the performance of the loudspeaker. This work is to find the resonant frequencies and vibration mode shapes of the proposed PVDF film loudspeaker as well as its frequency response over the audible range (20 Hz – 20 kHz). To measure the dynamic response of the PVDF film loudspeaker to driving voltage, the authors make a test frame by acrylic plates. The PVDF film loudspeaker is clamped in the test frame by four screws. A sine-wave AC voltage is applied on the PVDF film loudspeaker by a function generator. The driving frequencies are scanned in the audible range, namely 20 Hz to 20 kHz. The vibration of the PVDF film loudspeaker is measured by a laser Doppler Vibrometer. This article studies on the coupled electromechanical characteristic of the compound membrane of the PVDF film loudspeaker. In the near future, the design of the PVDF film loudspeaker can be optimized according to the results of this work.

碩士
義守大學
材料科學與工程學系
103
In this study, electroless Nickel and Nickel – Cobalt coatings were deposited on three kinds of flexible substrates (graphite paper, titanium foil, carbon fiber paper), and these coatings further etched in a 5M HNO3 solution to improve the electrochemical characteristics. Using a three-pole electrode system, cyclic voltammetry and charge-discharge curve were measured to calculate the specific capacitance, and electrochemical impedance spectroscopy (EIS) was used to analyze the electrochemical reaction mechanisms. In addition, the effects of Ni/Co ratios of Ni-Co-P system and etching time on the microstructure and the specific capacitance were explored in details. The results showed that nickel-phosphorus coating on the graphite paper substrate exhibited the highest specific capacitance (71 F/g) than the others (Titanium foil: 30 F/g; carbon fiber paper: 52 F/g) under the same plating conditions. After etching in HNO3 solution for 10s, the specific capacitance of Ni-P coating on graphite paper increased up to 335 F/g, in which the specific capacitance of Ni-P coating increase to 4.7 times as compared with the unetched one. Once the etching time was further increased, it did not significantly increase the specific capacitance. Microstructures analysis revealed that an appropriate etching time can effectively increase the surface area of Ni-P coatings and the prolonged etching time damaged the Ni-P coatings and finally the etched coatings peeled off. To deposit Ni-Co-P coatings on graphite paper, the pH value of electroless bath should be changed into 9. The specific capacitance value is not significantly improved by the addition of Co, but the corrosion resistance of the coating is improved. After etching in 5M nitric acid solution, it also significantly raised specific capacitance, for Ni/Co=70/30 system, at a scan rate of 10mV/s, from 51 F/g to 237 F/g. Based on the above the results, the acid-etching treatment effectively increased the specific capacitance of the Ni-P and Ni-Co-P system, it is expected that such method be applied to other material systems.

博士
國立清華大學
化學工程學系
94
This study is mainly to discuss the positive temperature coefficient (PTC) effect of Polymer Conductive Composite (PCC), which includes the preparation for Ni composite particle, polyimide and polystyrene-co- butylacrylate matrix, particularly the temperature-resistance behavior of composite films. What would be the impact to PTC feature for composite film, by changing the combination of above factors, as well as the process, is our major interest in overall study. The study consists of 3 main topics: Part I. Micro Ni-plated SiO2 particle/polyimide matrix system Part II. Core-shell type P(S-DVB) Ni-plated particle/P(S-co-nBA) matrix system Part III. The thickness-direction PTC feature of micro Ni powder/ polyimide matrix system

碩士
國立清華大學
電機工程學系
98
This work presents a new scheme of reliability mechanism in storage systems. The new scheme defines reliability and protects data in the scope of file, which is very different from traditional strategies, which protect data in the scopes of storage block or the whole device. The scheme provides the possibility to store highly reliable files and normal ones under the same file system, increasing flexibilities but decreasing costs of storage systems. To implement this scheme, Linux virtual file system (VFS) layer has been modified to perform reliability related operations during I/O calling paths and provide new interfaces for file systems to define their own reliability methods. A modified Ext2 file system with different levels of reliability has also been built as an example design of the new scheme. Depending on reliability levels, files in the example design are protected by parity check and Reed-Solomon Code of different code rates, which incur different overheads.

碩士
國立中興大學
光電工程研究所
100
In this thesis, we study a nanocomposite dielectric for flexible a-IGZO Thin Film Transistors, it combines both organic polymer PVP and inorganic nanoparticle aluminum oxide to perform the gate dielectric.The uniqe advantage of the gate dielectric is that simple and solution process, first we find the optimization parameter of gate dielectric which used as a MIM structure, and we spin coated the gate dielectric in the glass and PEN substrate.In combination of both organic and inorganic gate dielectric electrical characterization was well and good, and we found two major advantages one is thate always in the enhancement mode, and the other one is robust when it is bending more than one hundred times.The TFT performance was without adding Al2O3 was exhibit 0.48 cm2/V-s of mobility, 0.3 V of threshold voltage, 104 of on off ratio and 0.98V/dec of subthreshold swing, and after adding the Al2O3 the TFT was improved to 5.01 cm2/V-s of mobility, 1.9 V of threshold voltage, 106 of on off ratio and 1.2V/dec of subthreshold swing.

碩士
明新科技大學
電機工程系碩士班
103
In this paper, three materials including glass epoxy (FR4), polyimide film (PI) and photo paper (PP) are used as the substrate of antenna. IE3D software is used to design planar dipole antennas with various substrates.The fabricated planar dipole antenna with FR4 substrate can be applied to 1200MHz and 1800MHz frequency bands, the antenna withPI substrate can be applied to 2100MHz, 4800MHz and 5800MHz frequency bands, and the antenna with PP substrate can be applied to 5300MHz and 5600MHz frequency bands. In this study, the size parameter L2 and the substrate material of antenna are changed to observe the variations of antenna characteristics. The PI film thickness and curing process are discussed in this thesis.The thickness of PI substrate about 0.12mm and two vacuum curing processesare obtained to achieve betterimpedance value. Changing L2 parameters of planar dipole antennas with FR4 substrate, two antennas are proposed in this study.The antenna withbandwidth from1070MHz to 1370MHz,reflection loss -29.3dB and the maximum gain 4.296dBi at 1200MHz can be used for 1200MHz wireless monitors. The antenna with bandwidth from 1.78MHz to 1.98MHz,reflection loss -32.3dB and maximum gain 3.593dBi at 1800MHz can be used in LTE 1800MHz. With suitable L2 parameter, the inkjet printer is used to print silver nanoparticles and fabricate three flexible thin-film antennas with PI substrates. The bandwidths of these antennas are from 1500MHz to 2500 MHz,4200 MHz to 4950 MHz and 5400 to 5800 MHz.The reflection loss is -17.6dB and maximum gain is 2.183dBi at 1200MHz. The reflection loss is -38.9dB and maximum gain is 3.509dBi at 4800MHz. The reflection loss is -16.4dB and maximum gain is 3.599dBi at 5800MHz. These antennas can be applied to LTE 2100MHz, C-Band 4800MHz, and WLAN (801.11ac) 5800MHz frequency bands. PP substrate, suitable L2 parameter, and silver nanoparticles are used to produce three flexible thin-film antennas with PP substrates. The bandwidths of these antennas are from 5100MHz to5500MHz, 4600MHz to 5400MHz, and5300MHz to 5700MHz.One antenna exhibits reflection loss-22.5dB,maximum gain3.257dBi at 5300MHz and another antenna with reflection loss -37.6dB andmaximum gain4.175dBiat 5300MHz. The reflection loss is -32.4dB and the maximum gain is 4.834dBi at 5600MHz. These antennas can be applied to WLAN (801.11ac) 5300MHz, WLAN (801.11ac) 5600MHz. Keywords: planar dipole antenna, silver nanoparticles, flexible thin-film,LTE, WLAN, PI, PP.

碩士
國立臺灣師範大學
物理學系
103
In our life, there are more and more portable electronic devices and wearable electronic devices when the technology is improving all the time. Therefore, the requirement of batteries is more important now. Because all-solid-state thin film battery feature with good safety and high energy density, it is much potential for the development of future work. In our experiment, we try to make all-solid-state thin film batteries. We use ruby mica scratchfree to be the substrate. First, we deposit platinum by direct current sputtering as a current collector. Then, we deposit lithium cobalt oxide (LiCoO2) cathode material and lithium phosphorus oxynitride (LiPON) solid electrolyte on the platinum current collector by radio frequency sputtering. Finally we fabricate the lithium metal and aromatic polyurea to be the anode material and encapsulation by thermal evaporation. We use the furnace and rapid thermal annealing (RTA) to heat the cathode material, and control the heating rate of machine. We use x-ray diffraction to analyze the crystalline structure. Scanning electron microscope is used to observe the surface morphology, and capacity test is able to decide the chemical properties of cathode material. In the part of solid electrolyte, we use hot plate to heat the LiPON film in different temperature. And we measure the electrochemical impedance spectroscopy to calculate the ion conductivity. Using the rapid thermal annealing (RTA) at the rate of 260oC/min is a good way to heat the LiCoO2 film. And we use hot plate at the 200oC to do the heat treatment of LiPON film. Finally, we use the thermal evaporation to evaporate the lithium metal. The complete all-solid-state thin film battery can do the cycle test and light the LED.

This work documents the fabrication and characterization of electrochromic thin-film transistors (ECTFTs) based on tungsten oxide (WO3). The ECTFTs exhibit double functionality (optical and electrical modulation) and were deposited on Corning glass and polyethylene naphthalate (PEN) by radio-frequency (RF) magnetron sputtering in an argon-oxygen atmospherewith no intentional substrate heating. The resulting amorphous WO3film connects source and drain in a planar configuration with three different architectures(conventional, interdigital and back-electrode) and isgated by a drop-casted lithium-based polymer electrolyte (LiClO4:PC). EC films were characterized using X-ray diffraction (XRD), atomic force microscopy (AFM)andopto-electrochemical measurements, the electrolyte by electrochemicalimpedance spectroscopy (EIS) and the ECTFTs by static and dynamic electrical characterization. Thinner EC films (75 nm) evidenced lower optical density (ΔOD) and color efficiency (CE) of 0,26 and 21,85 cm2C-1, respectively, but faster EC reaction kinetics, with bleaching and coloration times (tband tc) of 1,8 and 3,8 seconds, respectively. In terms of electrical properties the best performing ECTFT architecture (interdigital) showed an ION/IOFFof 2,81x105and a transconductance of 2,24 mS. The back-electrode architecturehowever showed better ionic movement control in the channel(adjustable VON)with enhanced colorations, making ita better candidate for a two-in-one (pixel + transistor) solution for display applications.

碩士
國立高雄應用科技大學
化學工程系碩士班
95
At present, TCO material is often applied in the manufacturing of LCD, plasma screens, and in flat-panel displays as panel electrode film material. However, the main application is using the physical vapor deposition (PVD) based vacuum evaporation method or magnetic enhanced sputtering to deposit thin film metal TCO, such as indium tin oxide (ITO). This glass material substrate has such disadvantages as fragility, heaviness, and the failure to fit in the continuous rolling manufacturing procedure. Along with the introduction of the roll to roll production model into flexible manufacturing procedures of panels, some transparent conducting films using polymer flexible material as the substrate to form flexible transparent conducting film, have the potential to be future electrode materials of flexible displays. Few studies on the physical properties of flexible transparent conducting film have been conducted; therefore, a series of physical properties of flexible transparent conducting film were in this study researched to provide reference for manufacturers to further develop flexible displays. This study makes use of the low resistance range in order to measure the chip resistor of flexible transparent conducting film, for addressing the influence of annealing temperature on resistor. Through the measurement of two-dimension apparatus, we are able to acquire the dimension changes of flexible transparent conducting film before and after annealing, to observe the influence of annealing temperature on the dimension stability of material, to examine whether annealing temperature will change the surface structure, element composition and content, or if it will lead to major defects via SEM and EDS. In addition, aqueous solution containing 5% acetic acid is used for etching conducting film to examine the influence of temperature on the etching speed on conducting film. In the end, Osuka optical inspection equipment and a haze meter are used to the measure the influence of light transmission and haze after substrate is applied on the conducting film.

碩士
國立臺北科技大學
環境規劃與管理研究所
93
Corporate sustainability has a challenge, for it not just tries to create financial benefits, but also intents to pursue “win-win” vision for achieving both economic development and environmental protection. Leading company, such as 3M has carried out innovative “cleaner production” and “waste minimization” programs since 80s’, which resulted in accomplishing various environmental goals, as well as creating 750 million USD of financial benefits. PVC industry, although contributes quite a lot to the Taiwan’s economic miracle during past decades, has long being considered as a highly polluted and “unhealthy” industry. In order to realize the vision of sustainability, PVC firms in Taiwan have gradually switched their traditional end-of-pipe treatment techniques to the innovative measures, such as waste minimization, cleaner production, pollution prevention and industrial ecology for improving the resource productivity. These approaches enhance business image, also help company to cut-cost as well. In this study, flexible PVC film industry is selected for analyzing the possibility of forming an eco-industrial system for PVC industry. A flexible PVC film factory is used as a case study to examine the pathways, strategies and benefits of forming such an eco-industrial system. The study also intentionally tries to evaluate and verifies the continuum of industrial symbiosis theory through the flexible PVC film industry. It is concluded that the benefits found from the case study, both ecological and economical, prove that industrial ecology system formed within PVC industry will benefit not just industry itself, but also the environment and whole society.

碩士
國立臺灣科技大學
化學工程系
106
This thesis was describes a composite of 2,2,6,6-tetramethyl-1-piperidinyloxy radical (TEMPO) oxidized cellulose nanofibers (TOCNFs), Zinc oxide (ZnO) and carbon dots (Cdots) used as a photoanode and a composite of TOCNF and polypyrrole(PPY) as a counter electrode which was applied on the dye-sensitized solar cell. TOCNF was prepared based on the TEMPO-mediated oxidation procedure, and ZnO nanorods(ZnO NR) and ZnO nanowires(ZnO NW) and Cdots were prepared by hydrothermal method. And ZnO nanoparticle (ZnO NP) was prepared by polyol method. ZnO NR was in-situ grown on TOCNF, the composite of TOCNF and ZnO NR was prepared, and this was used as a photoanode in dye-sensitized solar cell. ZnO NP optimized 100 mg was loaded on TOCNF-ZnO NR electrode, the energy conversion efficiency 0.05 % was obtained from this electrode. The weight ratio of ZnO NP with Cdots was optimized 1/0.6 and loaded on the TOCNF-ZnO NR electrode. The energy conversion efficiency 0.117% was obtained from this electrode. The ratio of COOH: NH2 in Cdots was optimized 1:1.5, then energy conversion efficiency was 0.18%, could be enhanced from 0.18 to 0.246% by changing ZnO NP to ZnO NW. TOCNF-ZnO NW electrode which was loaded ZnO NP and Cdots had better photovoltaic performance than TOCNF-ZnO NR electrode which loaded ZnO NP and Cdots, and the energy conversion was increased from 0.18 to 0.4%.

碩士
國立中興大學
奈米科學研究所
106
A high-sensitive, low-cost and portable strain sensing technology based on gold nanoparticles (AuNps) is developed. For this goal, AuNPs were self-assembled on flexible substrates, forming closely packed multilayer films by centrifugal method, followed by appropriate chip packaging technique. AuNPs were modified with 3-mercaptopropionic acid(MPA), which has a length of about 0.9nm. As such the typical resistance of our sensors are in the range of 1-20 MΩ. When strains are applied to the substrate, the distance between adjacent AuNPs is changed, inducing the variations on the device resistance and capacitance. The sensors made on polydimethylsiloxane (PDMS) substrate may have the gauge factor up to 430. It can sense the pressure change with a sensitivity of 0.396kPa^(-1). The nominal power consumption is very low, about 15~24 nW. The capacitance change with a sensitivity of -36.4 and 22.5. For studying the response time, sensors were tested under mechanical vibrations of different frequency. The resistance change can be clearly identified up to a vibration frequency of 1 kHz. With the different frequency response, the sensors can find theirs applications in human pulse sensing, motion detection, and voiceprint recognition.

碩士
正修科技大學
電機工程研究所
107
In this study, the LixWO3 powder was fabricated by WO3 mixed with Li2O. The electrochromic films were prepared by electron beam evaporation. It was expected that the amount of charges storage could be enhanced by using the doping method, which makes the optimal performance of electrochromic devices (ECD). By constructing the ECD structure of Li0.2WO3/ Gel-electrolyte / ITO PET, the optimal characteristics of ECD are obtained at applying voltage of 1.8V, in which, the transmittance change (ΔT%) is 33%, the optical density (ΔOD) is 7.56, the intercalation charge (Q) is 5.94 mC/cm2 and the color efficiency (η) is 92 cm2/C at wavelength of 550 nm, respectively. The transmittance of colored state increases from 7% to 38% after 24 hour without biased voltage at R.T. The previous study was deposited the optimal properties on the glass substrate and this study was deposited on the PET substrate. This study was worse than the previous study because when PET was prepared by hot pressing, the films have cracking and peeling which will let the devices become uneven during coloring/bleaching.

碩士
國立中山大學
材料科學研究所
96
This paper describes an investigation into the fabrication of absorber layer CuInSe2 films by co-evaporation process. And we used the stainless steel substrates to manufacture Al / ZnO:Al /ZnSe(CdS) / CuInSe2 / Mo /SiO2 / Stainless Steel(SS) flexible thin-film solar cell. In this study, we fabricated the main absorber layer CIS thin film by co-evaporation process including two steps, and CIS thin films parameters were estimated by sheet resistance. Under one-sun (AM1.5,100mW/cm2) conditions solar simulator, we compared the solar cell with different thickness of absorber layer, co-evaporation process and composition to improve solar cell performance. The energy conversion efficiency of the CIS thin-film solar cell (Al/ AZO/ CdS /CIS/Mo/ SLG) was 4.5﹪(Voc =0.38 V，Jsc = 30.5 mA ，FF = 38.6 ﹪), flexible solar cell (Al/AZO/CdS/CIS/Mo/SiO2/SS) was 2.6%( Voc =0.2 V，Jsc = 41.7 mA ，FF = 31.2 %).

碩士
國立臺北科技大學
有機高分子研究所
100
The flexible reflector film is a kind of high reflectivity and low light transmittance function of diaphragm, which is widely used in 3C products. Currently available reflector film can be divided in three type, such as (1)cyclical multilayer reflector film (2)metal reflecor film (3)white reflector film. Among those, metal reflector film is easier processable than cyclical multilayer reflection film, and has better work wavelength range and the reflection rate than white reflector film. However, metal reflecor film is easily oxidized in air. Therefore, a layer of cover layer is necessary to to protect the metal layer.. In this thesis, a cover layer with white ink coating on metallic reflector using roller to roller coating process is presented. Two metallic reflector films (Ag and Al) are investigated. Applying white ink coating, the metallic reflector films showed the reflectivity increased 2% and total light transmittance decreased 2%. The resulting film has passed after the weathering test.

碩士
國立雲林科技大學
電子與資訊工程研究所
94
ABTRACT In this study we use Indium-Tin Oxide (ITO) to deposit films on flexible substrate as the conductive electrode used for flexible display. Besides we produced MIM capacitance and measured electrical properties to improve the character of ITO films. ITO films were deposited by Rf reactive magnetron sputtering. We design several conditions such as RF power, substrate temperature, process pressure, and the distance between ITO target and substrate to obtain better films of transparent conducting oxide. At the result we obtained good electrical and optical properties. The resistance ratio of ITO films is 5.67×10-4 Ω•cm and The UV-visible spectra indicate that the average optical transmittance of ITO films is around 83% in the visible range by 4-inches ITO target. And then we produced MIM capacitance, used HfO2 and Al for dielectric layer and upper electrode. We also deposit Ti film used for buffer layer and used Ar plasma treatment to improve the quality of ITO films. Finally we find the best condition with 5 min and 3 min Ar plasma treatment on the surface of flexible substrate and ITO films that we obtained the best electrical properties.

碩士
國立交通大學
顯示科技研究所
98
In this study, we fabricated flexible organic thin-film transistors on stainless steel substrates, and their electrical characteristic were measured under different bending conditions. We found that the electrical characteristic was increased under compressed strain and decreased under tensile strain. From the analysis of the results, we deduced that the variety of intermolecular force change the device characteristic under bending strain states. mechanical strains influence the barrier height between the grains of pentacene thin-films, thereby resulting in the variation of device characteristic.