Abstract Printed electronics offer unique possibilities for the development of devices and manufacturing methods. A prime example of printed electronics where the production volume can be significantly increased are solution-processed organic solar cells. Roll-to-roll (R2R) technology has made it possible to print solar cells almost as fast as newspaper. Unfortunately, the performance of printed devices depends strongly on film morphology, which is affected by the behaviour of the used ink on the confining surface - wetting. Key parameters that influence the wetting behaviour include surface energy, ink formulation, surface roughness, solvent properties, processing temperature and pre/post-treatments (heat, acid or plasma) and chemical heterogeneity. Importantly, a precise control of wetting and, consequently, film morphology is emphasized by many authors as an important factor for the commercialization of printed solar cells. This research focuses on measuring and analysing the influence of substrate processing temperature as well as plasma and UV pre-treatments on the wettability of various inks and substrates used in Organic Solar Cell (OSC) fabrication. It also explores the application of interesting novel materials, such as nanocellulose, in solar cell manufacture. The main tool applied here is the contact angle measurement method, since it is commonly used to obtain quantitative data describing the behaviour of ink droplets on substrate surfaces. Chief among the achieved results is the finding that the three factors mentioned above significantly influence ink-substrate interactions. Therefore, manipulation of plasma and UV treatments as well as substrate processing temperature, allow us to control wetting properties and, in consequence, the printing process. Another important result shows that the degree of control is strongly dependent on ink formulation and material composition and must, therefore, be taken into account in process development. These findings will contribute to a faster development of printed solar cells and their manufacturing conditions and requirements. / Tiivistelmä Painettava elektroniikka tarjoaa uusia mahdollisuuksia elektronisten laitteiden ja niiden valmistusmenetelmien kehittämiseen. Liuoskäsitellyt orgaaniset aurinkokennot ovat hyvä esimerkki painetun elektroniikan tuotteesta, jonka tuotantomäärää on voitu kasvattaa merkittävästi. Rullalta rullalle (engl. Roll-to-roll, R2R) -menetelmän avulla aurinkokennoja voidaan painaa lähes samalla nopeudella kuin sanomalehteä. Painettujen laitteiden suorituskyky riippuu suuresti tuotetun kalvon morfologiasta, johon vaikuttavat tuotantoprosessissa käytettyjen materiaalien kostumisominaisuudet. Tärkeimmät kostumiskäyttäytymiseen vaikuttavat parametrit ovat pintaenergia, pinnan karheus, musteen koostumus, liuotinominaisuudet, käsittelylämpötila, esi- ja jälkikäsittely (lämpö, happo tai plasma) sekä kemiallinen heterogeenisyys. Kostumisen, ja sitä kautta kalvon morfologian, tarkka säätely on tärkeää painettujen aurinkokennojen kaupallisen hyödyntämisen kannalta. Tässä väitöskirjatyössä mitataan ja analysoidaan käsittelylämpötilan sekä plasma- ja UV-esikäsittelyiden vaikutuksia orgaanisten aurinkokennojen valmistuksessa käytettyjen musteiden ja alustojen kostumisominaisuuksiin sekä tarkastellaan aurinkokennoliuoksissa käytettäviä uusia, mielenkiintoisia materiaaleja, kuten nanoselluloosaa. Työssä eniten hyödynnetty menetelmä on kontaktikulman mittaus, joka on yleisesti käytetty tapa hankkia kvantitatiivista tietoa mustepisaroiden käyttäytymisestä erilaisilla pinnoilla. Keskeisin saavutettu tutkimustulos on se, että kaikilla yllämainituilla kolmella käsittelyllä on huomattava merkitys musteen ja alustan vuorovaikutuksiin. Näin ollen plasma- ja UV-käsittelyillä sekä alustan käsittelylämpötilan säätelyllä voidaan hallita kostumisominaisuuksia ja sitä kautta koko painatusprosessia. Toinen tärkeä löydös on, että musteen koostumus ja alustan materiaali vaikuttavat siihen, kuinka voimakkaasti kostumista voidaan hallita. Näin ollen ne täytyy ottaa huomioon painatusprosessin suunnittelussa. Työssä saavutettuja tuloksia voidaan käyttää painettujen aurinkokennojen sekä niiden tuotantomenetelmien kehittämiseen.

Abstract In this thesis, preparation of carbon nanotube (CNT) inks and inkjet printing of aqueous dispersions of CNTs for certain electrical applications are studied. The nanotube inks prepared in this work are based on chemically oxidized CNTs whose polar side groups enable dispersion in polar solvents. Subsequent centrifugation and decanting processes are used to obtain stable dispersions suitable for inkjet printing. The inks are based on either carboxyl functionalized multi-walled carbon nanotubes (MWCNTs), carboxyl functionalized single wall carbon nanotubes (SWCNTs) or SWCNT-polymer composites. The applicability of MWCNT inks is firstly demonstrated as printed patterns of tangled nanotube networks with print resolution up to ∼260 dpi and surface resistivity of ∼40 kΩ/□. which could be obtained using an ordinary inkjet office printer. In addition, MWCNT inks are found to exhibit spatial ordering in external magnetic fields due to entrapped iron catalyst nanoparticles in the inner-tubular cavity of the nanotubes. Ordering of nanotubes in the inks and in drying droplets placed in relatively weak magnetic fields (B ≤ 1 T) is demonstrated and studied. The high electrical conductivity and optical transparency properties of SWCNTs are utilized for enhancing the conductivity of transparent poly(3,4-ethylenedioxythiophene):poly(styrenesulphonate) (PEDOT:PSS) films. Polymer-nanotube composite materials are inkjet printed on flexible substrates. It is demonstrated that incorporation of SWCNTs in the thin polymer films significantly increases the electrical conductivity of the film without losing the high transparency (> 90%). The structure of composite films is studied using atomic force microscopy (AFM). The electronic properties of deposited random SWCNT networks are studied. The amount of deposited SWCNT is controlled by the inkjet printing technique. In dense networks the current-voltage behaviour is linear whereas for sparse films the behaviour is nonlinear. It is shown that the conduction path in dense films is through the metallic nanotubes, but in sparse films the percolation occurs through random networks of metallic and semiconducting SWCNTs having Schottky-type contacts. The existence of Schottky-junctions in the films is demonstrated with field-effect transistors (FET) on Si-chips and on polymer substrates. The latter is demonstrated as fully printed transistors using a single ink as a material source. FETs are further utilized as chemical-FET sensor applications. The performance of resistive CNT sensors and their comparisons with chem-FETs in terms of selectivity are studied for H2S gas.

Nous proposons dans ce travail une analyse de la transposition du journal imprimé vers le journal web, à travers le cas de deux importants journaux colombiens. Observer et décrire la transposition nécessite d'abord de faire un arrêt sur le texte pour rendre compte du mode de fonctionnement des différentes strates qui lui rendent son épaisseur et qui participent à la définition des modalités énonciatives et pragmatiques qui lui sont propres. Mais ensuite, il faut considérer la nature dynamique du processus qui permet la projection et la circulation des formes textuelles dans une nouvelle sphère médiatique. L'objectif principal de ce travail est donc de comprendre comment se réalise la transposition du journal à partir de l'observation de la Une, afin de voir la forme qu'il acquiert lors de son intégration au numérique. Pour cela, nous partons d'une analyse de la structure du texte et des interactions que les composantes métatextuelles et paratextuelles entretiennent dans l'objet d'écriture, pour ensuite déterminer la manière dont ces composantes se déterminent dans l'hypertexte. Il s'agira en particulier d'observer les modalités de hiérarchisation de l'information propres à chaque système textuel, mais aussi des modes d'organisation des contenus selon un scénario. Nous montrons que ce qui est en jeu dans la transposition, c'est la mise en place de parcours hypertextuels à partir de l'interface graphique, parcours que le lecteur doit interpréter et comprendre pour construire sa propre pratique de lecture. / We propose in this thesis an analysis of the transposition of the printed newspaper to the web, through the case of two important Colombian newspapers. Observe and describe the transposition requires first to make a stop on the text to reflect the mode of operation of the different textual layers that make its thickness and participate in the definition of the enunciative and pragmatic terms that are specific to it. But then we need to consider the dynamic nature of the process that allows the projection and the movement of textual forms into a new media sphere. The main objective of this work is to understand how to realize the transposition of the newspaper from the observation of its front page to see the shape that it acquires when it is integrated into the digital. For this, we start with an analysis of the text structure and the interactions that metatextual and paratextual components maintain within the writing object, then we describe how these components are determined in hypertext. In particular, it is necessary to observe the hierarchical arrangements of information in the textual system, but also to understand the different ways of organizing the content according to a specific scenario. We show that what is important in the transposition is the creation of hypertextual access from the interface, which need to be interpreted in order to build a reading practice.

In resource recovery from end-of-life printed circuit board (PCB), the physical processing route is considered most environmentally friendly. The −75 µm fraction generated during the comminution assays well above many precious and base metal deposits, but contributes overall drop in value recovery. This investigation was aimed at exploiting the versatility of froth flotation for beneficiation of the PCB comminution fines. Chemical composition characterisation work shows wet assay of constituents in the sample vary with digestion condition. Absolute assays as for hazardous constituents thus require comparison of data from more than one digestion condition. Comparative assaying of samples from beneficiation treatments can use aqua regia digestion which gives a less hazardous procedure compared to hydrogen fluoride combined with microwave and nitric acid treatments. It also gives leach liquor from which all constituent elements can be analysed, compared to that from total digestion via sodium peroxide fusion. For this sample total digestion will therefore not always give better results compared to partial digestion. Findings also show that thermogravimetric analysis may not be recommended in PCB characterisation. It gave no distinct inflexion point to characterize any constituent. This is due to the very diverse material constituents of the sample. Further on characterisation, the sample gave a loose bulk density lighter than water, and true sample density of 3 g/cm3. This coupled with surface hydrophobicity observed necessitates that pulping the sample must be done under water. Light optical and scanning electron microscopy showed particle liberation was very high, but not total. Morphology of the metallic particles was very diverse, with average circularity shape factor of 0.63. This coupled with the material diversity is a major constraint in sub-sieve size analysis of the sample. As shown by scanning electron microscopy energy dispersive X-ray spectroscopy, the liberated particles themselves contain more than one chemical element, being alloys. Beneficiation operation therefore cannot attempt to separate such particles into constituent elements but some bulk collection of metallic values into a concentrate. Reverse flotation of metallic values based on a scheme described as natural hydrophobic response (NHR) was found successful. Favorable kinetics under the scheme gave about 500 rpm and 500 ml/min aeration rate, at 300 g sample in a 3.5 l Leeds cell. Without the use of a collector, natural hydrophobic response was observed. The system also gave a stable froth without the aid of a frother. Investigations (surface tension and dynamic froth stability height measurements, combined with general literature) show the NHR froth is a fine particle stabilised froth, and not surfactant stabilised. Au and Pd, were among the elements best enriched into the sink; 64 % recovery for Au at enrichment ratio of three. Flotation over narrower and coarser fraction (+106 – 75 µm) shows the NHR scheme can be successfully applied at this size. Chemical conditioning schemes investigated shows very minimal responses to reagents. Potassium amyl xanthate (PAX) did not condition the metallic particles for flotation remarkably as it does with native metals. Sulfidation with sodium hydrogen sulfide shows a little improvement in response to PAX. Sodium mercaptobenzothiazole – a very selective collector for tarnished copper and lead minerals – did not show such selectivity in the PCB comminution fines pulp. Some cationic pull with tetrabutyl ammonium chloride towards selective pull of non-metallic values after NHR pull has subsided was observed, although very little also. Macromolecular depression with carboxyl methyl cellulose did not subdue the natural hydrophobic response up to profuse percentage dosages. Depression by lowering surface tension, described as gamma depression, using Betamin 127A (active constituent: ethoxy nonyl phenol) was effective to wet hydrophobic particles, but still not helpful for selective pull after chemical conditioning. At the lowered surface tension, frothing sets in coupled with entrainment. Probable causatives for the poor response to reagents are surface oxidation of the metallic particles and depression by calcium ions in pulp. Surface studies with field emission scanning electron microscope and auger electron spectroscopy composition depth profiling, show presence of organic layers on the surface of the metallic particles. The surfaces were also found to be oxidised down to about 340 nm depth profiled. None of the surfaces is a pure alloy, but occurring in forms that will be relatively inert to reagents. Beside these, from aqua regia wet assaying, the sample contains about 7 % calcium by mass, and ICP-MS trace element analysis of the process water confirms calcium presence up to 7 ppm equilibrium concentration in the pulp. Judging from the responses, the natural hydrophobic response scheme can be well recommended for PCB comminution fines flotation. Optimisation of the performance of the scheme responds remarkably well to kinetic parameters variation. With the generally low impeller energy and aeration rate found favourable for PCB CF flotation, and the zero reagent cost (no collector, no frother) of the NHR scheme, PCB comminution fines flotation shows good prospects. / Thesis (PhD)--University of Pretoria, 2010. / Materials Science and Metallurgical Engineering / unrestricted

The purpose of this thesis was to explore the ways the printed word in James Joyce’s Ulysses opens new and alternative paths towards the interpretation of the text. We show how it induces multiple chains of associations beyond the act of reading, which start at the visual, spatialized sequencing and contiguity of letters, words and sentences, their layout on the page, or the persistence or absence of punctuation. After initial observations of the visual prevalence of the written word over its auditory capabilities as noted in the “Aeolus” chapter (e.g.: puns that can be realized only in writing; meanings that can be accessed not by reading but by observing the spatial arrangement of text), two other chapters of the book—“Ithaca” and “Penelope”— were analyzed to determine if such assumptions could be applied to other sections of the novel. Random passages from yet other sections were used as illustration. Our analysis suggests that throughout “Ulysses” meaning derivation may take place beyond the effect of rhetorical figures, and often can be the result of a visual/spatial associative chain.

De nos jours, le domaine biomédical est en pleine croissance avec le développement de dispositifs thérapeutiques innovants, bas coût, pour le diagnostic, le traitement ou la prévention de maladies chroniques ou cardiovasculaires. Ces dernières années ont connu l’émergence des polymères semi-conducteurs, alternative intéressante aux matériaux inorganiques, présentant des propriétés uniques de conduction ionique et électronique. Tout d’abord, j’ai axé mes travaux de recherche sur le développement et l’optimisation d’une encre conductrice à base de PEDOT:PSS, parfait candidat comme matériau, pour la transduction des signaux biologiques en signaux électriques, compatible avec le process jet d’encre, pour la réalisation de dispositifs imprimés. Puis mes travaux se sont orientés vers la conception et l’étude d’électrodes imprimées sur supports papiers, tatous et textiles permettant des enregistrements long termes d’électrocardiogrammes (ECG) ou électromyogrammes (EMG), présentant des performances similaires aux électrodes commerciales, utilisant un système d’acquisition spécifique pour la mesure d’activités électriques de tissus musculaires. Puis dans un second temps, je me suis penchée sur l’impression sur support papier, de transistors organiques électrochimiques (OECTs) fonctionnalisés, afin de permettre la détection d’éléments biologiques ou chimiques comme l’alcool. Ces travaux proposent une nouvelle voie pour la conception de dispositifs innovants biomédicaux à bas couts, imprimés, permettant la personnalisation des produits pouvant être intégrés dans des dispositifs biomédicaux portables ou dans des vêtements « intelligents ». / With the evolution of microelectronics industry and their direct implementation in the biomedical arena, innovative tools and technologies have come to the fore enabling more reliable and cost-effective treatment. In this thesis I focus on the integration of the conducting polymer PEDOT:PSS with printing technologies toward the realization of performant biomedical devices. In the first part, I focus on the optimization of the conducting ink formulation. Following, I emphasize on the fabrication of inkjet printed PEDOT:PSS based biopotential electrodes on a wide variety of substrates (i.e., paper, textiles, tattoo paper) for use in electrophysiological applications such as electrocardiography (ECG) and electromyography (EMG). Printed electrodes on paper and printed wearable electrodes were fabricated and investigated for long-term ECG recordings. Then, conformable printed tattoo electrodes were fabricated to detect the biceps activity during muscle contraction and the conventional wiring was replaced by a simple contact between the tattoo and a similarly ink-jet printed textile electrode.In the last part, I present the potentiality of inkjet printing method for the realization of organic electrochemical transistor (OECTs) as high performing biomedical devices. A disposable breathalyzer comprised of a printed OECT and modified with alcohol dehydrogenase was used for the direct alcohol detection in breath, enabling future integration with wearable devices for real-time health monitoring. Their compatibility with printing technologies allows the realization of low-cost and large area electronic devices, toward next-generation fully integrated smart biomedical devices.

Stretchable Electronics is an emerging class of electronics that allow electronics to be bent, conform, ex and stretch while still retaining its full functionality. Other than bending, existing and conforming, adding stretchability to electronic systems can open up a new frontier for a myriad of applications. Especially in the medical sector, these stretchable devices can increase the scope of monitoring and ease and comfort of the patient. All kinds of wearable devices can be based on these technologies to augment our daily lives. With the kind of state of art technology available to the common man today, the bar has already been set for the performance of such devices. Hence, its imperative that these stretchable devices perform at this level and should be capable of adapting to the market to serve the mass requirement. Hence, it becomes inevitable to use metal interconnects to provide very low resistance and easy adhesion to commercial electronic components. Another aspect of such devices is an adhesion ability with which we can attach it to various kinds of surfaces. In this thesis, we propose a new multi-layered PDMS structure approach to bring stretchability in the device. For all kinds of adhesion requirements, various ratios of PDMS: Cross-linker have been used. These different ratios of PDMS: Cross-linker changes the mechanical and adhesive properties of the cured PDMS. Hence, the same material can be used as the stretchable substrate as well as to serve various adhesion requirements. A soft adhesion allows us to attach it to the human body/other surfaces. The adhesion can be tailored to be quite conformal and strong, yet its removal is quite gentle to the skin. A higher curing ratio makes the PDMS very sticky and soft. Aluminum/Copper foils can be directly stuck upon it and tracks can be then etched out to get a printed circuit. Since this adhesive layer is quite soft, it acts as a cushion and reduces the amount of stress transferred to the metal interconnects. Hence, stretchable circuits with metal interconnects can be realized. The electronic components can be then attached upon it via normal soldering techniques/using conductive ink. Various devices that can be built with the proposed techniques have been coined the term CAS (Conformal Active Sheets) to allow easy reference to such kind of devices. Since the substrate is soft, physical handling of such devices becomes an issue as one tries to transfer the circuit pattern. Hence, direct etching of the metal foil was explored via high pulsed current discharge technique. A CNC machine was also designed to try various ways of direct etching of the metal foil in an accurate and repeatable fashion.

Orientador: Yuzo Iano / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-27T18:51:43Z (GMT). No. of bitstreams: 1 Camilo_Edson_M.pdf: 3518346 bytes, checksum: 0264cd60aaed512cef0dacda58a43540 (MD5) Previous issue date: 2015 / Resumo: Este trabalho de Mestrado tem como objetivo contribuir para a área de placa de circuito impresso no que se refere ao projeto de layout focado não só em satisfazer as conexões das trilhas, mas nas regras de projeto com foco na redução de curto circuito de solda para o processo de solda por onda. Projetos de PCB (Printed Circuit Board) ou PCI (Placa de Circuito Impresso) envolvem uma série de conhecimentos no que se refere ao entendimento das funcionalidades dos circuitos e para tanto é importante que se faça o correto posicionamento dos componentes em grupos de circuitos pela funcionalidade; além disso, é importante que se conheça as regras de capacidade de corrente, de distâncias de isolação em função das tensões aplicadas, características de impedância, áreas de restrição mecânica entre outras. O que será visto neste trabalho está focado na aplicação de conceitos e considerações ligadas ao processo de montagem da placa eletrônica por solda a onda. Muitos dos defeitos que ocorrem num processo de montagem da PCB são atribuídos ao processo de montagem da PCB como, por exemplo, a temperatura da solda, o tempo de solda, quantidade de fluxo aplicado na placa, altura da onda de solda, etc. Recomendações sobre posicionamento de componentes PTH (Pin Through Hole) e SMD (Surface Mounting Devise) em relação ao sentido em que a PCB entra em direção à solda a onda, recursos de aplicação de serigrafia, tipos de laminados, de formato das ilhas de solda, adição de técnica de ladrão de solda e as recomendações da IPC (Association Connecting Electronics Industries) serão descritos neste trabalho. O correto entendimento dos defeitos que ocorrem durante o processo de montagem da PCB reflete na constante melhoria e aperfeiçoamento do projeto do layout da placa, que por sua vez resulta num processo de montagem de placa com menos ocorrência de defeitos de fabricação e consequentemente melhor qualidade do produto. Menos retrabalho nas PCBs significa menos custo de produção que reflete em maior lucro para as empresas. As propostas apresentadas neste trabalho são fruto de resultados práticos vivenciados na indústria e de pesquisa em literatura dos assuntos relacionados a defeitos em PCB e processos de solda por onda. O conjunto destas recomendações e seus resultados estão aqui descritos e ilustrados para servirem de referência aos futuros pesquisadores e leitores / Abstract: This work aims to contribute to the area of the printed circuit board in regard to layout design focused not only on satisfying the connections of the tracks but the design rules focused on reducing short- circuit solder for wave solder process . Projects PCB (Printed Circuit Board) involve a lot of knowledge when it comes to understanding the features of both circuit and is important to make the correct positioning of components into groups of circuits for feature addition is important to know the rules of current capacity, isolation distances depending on the applied voltage, impedance characteristics, areas of mechanical restrictions among others. What will be seen in this work is focused on application of concepts and considerations involved in the process of mounting the electronic board by solder wave. Many of the defects which occur in the process of assembling the PCB are assigned to the PCB assembly process such as the temperature of the solder, weld time , amount of flux applied to the board, solder wave height, etc. Recommendations on positioning components PTH( Pin Through Hole) and SMD( Surface Mounting Devise) relative to the direction in which the PCB goes toward the wave solder , screen printing application features , format type of solder lands , techniques of solder thief and the IPC ( Association Connecting Electronics Industries) recommendations will be described on this work . The correct understanding of the defects that occur during the assembly process of the PCB reflects on constant improvement and refinement of the board layout design, which in turn results in a process of mounting plate with fewer occurrences of defects in workmanship and consequently better quality product. Less rework means less PCBs in production cost which reflects in higher profits for companies. The proposals presented in this paper are the result of practical results experienced in industry and research literature on the subjects related to defects in PCB and wave solder processes. All these recommendations and their results are described and illustrated to better serve as reference for future researchers and readers / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica

Les machines de fabrication personnelle, comme les imprimantes 3D, permettent aux créateurs occasionnels de fabriquer leurs propres objets. Il est possible de créer des pièces rigides, mais aussi des pièces souples, flexibles ou malléables. Ces propriétés mécaniques ouvrent des perspectives inédites dans la recherche en Interaction Homme-Machine (IHM) puisqu’elles permettent de réaliser de nouvelles formes d’interaction. Le défi reste toutefois d'intégrer des capteurs et du retour visuel dans ces matières. Les sciences des matériaux ont introduit plusieurs techniques pour produire des éléments interactifs, mais leur application requiert une expertise spécialisée ou la disposition d’équipements très couteux. Ma thèse se concentre sur les professions créatives, comme les professionnels du design, les architectes, ou les chercheurs en IHM. Elle vise à accompagner leur processus de conception et de prototypage avec des matériaux souples et interactifs, produisant des objets élastiques, des modèles avec des formes reconfigurables, ou même des maquettes qui peuvent être découpées. De tels matériaux pourraient enrichir notre interaction avec le monde numérique de trois manières différentes : 1) les dispositifs prosthétiques et l’informatique ubiquiste 2) le design de produits personnels 3) la fabrication interactive. J’introduis d’abord une nouvelle méthode pour intégrer des capteurs tactiles, des capteurs de proximité et des écrans électroluminescents dans des matériaux de silicone étirables. Basée sur des techniques d’impression en sérigraphie, la méthode permet de fabriquer rapidement des interfaces étirables et peu coûteuses, qui peuvent être intégrées dans les vêtements et dans d’autres objets ordinaires. Deuxièmement, je présente une approche pour créer des modules de constructions interactives, qu’on appelle “Tangramis Interactifs”. Les Tangramis interactifs sont des matériaux souples, par exemple du papier, pliés et combinés ensemble pour créer des structures modulaires en 3D. Ils peuvent réagir au toucher, être actionnés, et intégrer des composants électroniques comme des LEDs. Nous utilisons une technique rapide d’impression par jet d’encre pour intégrer des capteurs et des circuits dans le papier. Nous avons également développé une interface graphique qui permet aux créateurs de concevoir la forme et le comportement interactif de leurs propres interfaces physiques avant de les imprimer sur papier. Troisièmement, j’introduis une méthode de fabrication de matériau capable à identifier sa forme (“shape-aware material”). Ce matériau peut détecter et communiquer sa géométrie en temps réel durant son découpage par un créateur. La méthode s’appuie sur une nouvelle technologie de capteurs de forme, imprimés par jet d’encre et intégrés dans du matériel de maquettage, comme le carton mousse. Notre logiciel aide les créateurs à générer du matériel de prototypage en 2D ou en 3D qui peut capter sa forme, en configurant la topologie des capteurs pour optimiser la précision du modèle. Il permet également d’établir le lien entre un modèle physique et sa représentation numérique dans un environnement CAO (Conception Assisté par l’Ordinateur), par exemple Blender et Unity. Notre approche soutient un processus de fabrication bi-directionnelle en intégrant des outils de modélisation à la fois physiques et numériques. / Personal fabrication machines, such as 3D printers, allow casual makers to create custom objects, which may also contain soft, flexible, or shape-changeable parts. Making use of these mechanical properties and developing novel forms of interaction opens up new possibilities for research in Human-Computer-Interaction (HCI). However, embedding sensing and output capabilities into material is still challenging. Although research in materials science has introduced a range of methods for producing interaction-aware materials, these methods require significant domain expertise and often rely on specialized and expensive equipment. My dissertation focuses on casual makers, designers, and HCI researchers, and investigates how to support their design and physical modeling tasks with interactive, non-rigid materials that are stretchable, shape configurable, or cuttable. I explore three directions on how such materials can enhance user interaction, with applications to wearables and ubiquitous computing, DIY product design, and interactive fabrication. First, I introduce a new fabrication method for embedding touch sensing, proximity sensing, and electroluminescent displays into stretchable silicone materials. Based on screen printing, the method allows for rapidly fabricating inexpensive and highly stretchable user interfaces than can be embedded in wearables and other everyday objects. Second, I present an approach for creating interactive paper-folded building blocks that we call Interactive Tangrami. Interactive Tangrami are made of flexible materials such as paper, folded and combined together to form modular 3D structures. They support touch sensing and actuation and can also integrate rigid electrical components, such as LEDs. We use a rapid ink-jet printing technique to apply sensors and circuits on paper. We also offer a software tool that helps makers to design the geometry and interactive behavior of their physical user interfaces and then print them on paper. Third, I introduce a method for fabricating shape-aware material, which is modeling material that captures and streams its own shape while being cut by an artist. The method is based on a novel inkjet-printable sensing technology that can be embedded into a variety of cuttable material such as foam-core. Our software toolkit helps makers produce 2D or 3D shape-aware material and customize its sensing topology for higher sensing accuracy. It also allows them to link the physical model with its digital copy in a 3D CAD environment, such as Blender and Unity. Overall, our approach supports a bi-directional fabrication workflow that combines both physical and digital modeling tools.

abstract: Since the advent of High Impedance Surfaces (HISs) and metasurfaces, researchers have proposed many low profile antenna configurations. HISs possess in-phase reflection, which reinforces the radiation, and enhances the directivity and matching bandwidth of radiating elements. Most of the proposed dipole and loop element designs that have used HISs as a ground plane, have attained a maximum directivity of 8 dBi. While HISs are more attractive ground planes for low profile antennas, these HISs result in a low directivity as compared to PEC ground planes. Various studies have shown that Perfect Electric Conductor (PEC) ground planes are capable of achieving higher directivity, at the expense of matching efficiency, when the spacing between the radiating element and the PEC ground plane is less than 0.25 lambda. To establish an efficient ground plane for low profile applications, PEC (Perfect Electric Conductor) and PMC (Perfect Magnetic Conductor) ground planes are examined in the vicinity of electric and magnetic radiating elements. The limitation of the two ground planes, in terms of radiation efficiency and the impedance matching, are discussed. Far-field analytical formulations are derived and the results are compared with full-wave EM simulations performed using the High-Frequency Structure Simulator (HFSS). Based on PEC and PMC designs, two engineered ground planes are proposed. The designed ground planes depend on two metasurface properties; namely in-phase reflection and excitation of surface waves. Two ground plane geometries are considered. The first one is designed for a circular loop radiating element, which utilizes a circular HIS ring deployed on a circular ground plane. The integration of the loop element with the circular HIS ground plane enhances the maximum directivity up to 10.5 dB with a 13% fractional bandwidth. The second ground plane is designed for a square loop radiating element. Unlike the first design, rectangular HIS patches are utilized to control the excitation of surface waves in the principal planes. The final design operates from 3.8 to 5 GHz (27% fractional bandwidth) with a stable broadside maximum realized gain up to 11.9 dBi. To verify the proposed designs, a prototype was fabricated and measurements were conducted. A good agreement between simulations and measurements was observed. Furthermore, multiple square ring elements are embedded within the periodic patches to form a surface wave planar antenna array. Linear and circular polarizations are proposed and compared to a conventional square ring array. The implementation of periodic patches results in a better matching bandwidth and higher broadside gain compared to a conventional array. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2020