The flexible and stretchable electronic market is increasing particularly in the field of biomedical electronics. Widely used printed silver conductive tracks today are only eligible for on-skin applications. However, for biomedical applications fully biocompatible, flexible and even stretchable materials for device fabrication are needed. This paper presents an additive printing approach to fabricate flexible and stretchable electronics by using a biocompatible platinum material. Usually, in order to realize electrically conducting Ptinterconnects by inkjet printing, it requires a furnace sintering at prohibitively high temperatures, which are not compatible with thermal sensitive polymeric substrates. This paper describes a high-power diode laser sintering (HPDL) and a flash lamp annealing (FLA) as promising alternative sintering methods. Both processes are eligible whereas laser sintering showed slightly better results. Bending tests and adhesive strength tests of platinum printed inks on polyimide with up to 180 000 cycles, show that printed platinum is a suitable biocompatible material for flexible electronics.

The appearance and design of a package are key properties to attract and to focus the attention of a customer. Print quality contributes to a great degree to achieve these requirements. Most critical perceived in terms of quality are print defects like mottling, gloss and stripiness, which all appear in the printing of corrugated board. Stripiness is especially critical because it is a defect directly caused by the corrugated board construction. A further cause can be generated by the production process of corrugated board. Pre-studies by Odeberg Glasenapp (2004) revealed a difference in surface micro-roughness between the regions on the peak line of the liner and the regions in the valley between two peaks of the corrugation. This knowledge was the basis for the work described in this thesis. In a first stage, laboratory trials were conducted with sets of coated and uncoated samples of various grammages. The trial was set-up in order to simulate the conditions in the corrugator as closely as possible. In the evaluations, it was found out that the settings were too high. For that reason, the coated samples were influenced to a too high degree and needed to be excluded from further evaluations. With the uncoated samples, on the other hand, a change in micro surface roughness was detectable. The roughness is decreased on the peaks and the gloss appearance was the conclusion. The analysis of the printed samples focused on shifts in colour and print density. It is unclear if both are affected only surface roughness changes and/or by the typical corrugated board effect of washboarding. A full-scale test was performed in order to confirm the results of the laboratory test. A test series was chosen with coated and uncoated outer liners. Contrary to the lab-test results, the uncoated grades showed no surface roughness changes. Instead, the coated samples were affected to a great extent. The changes in surface roughness and gloss appearance were similar to the lab-test. This confirms that the lab-test samples were exposed to heat, pressure and shear to a too high degree. The print analysis of the full-scale test did not agree with the laboratory test. Gloss lines were visually detectable, but they were difficult to measure. A reason could be that the ink is capable on forming an ink film layer on top of the surface of the paper. This would cover the micro roughness of the matt parts thereby creating an almost homogeneous glossy appearance. / QC 20101116

Wireless power transfer (WPT) systems are important in many areas, such as medical, communication, transportation, and consumer electronics. The underlying WPT system is comprised of a transmitter (TX) and receiver (RX). For biomedical applications, such systems can be implemented on rigid or flexible substrates and can be implanted or wearable. The efficiency of a WPT system is based on power transfer efficiency (PTE). Many WPT system optimization techniques have been explored to achieve the highest PTE possible. These are based on either a figure-of-merit (FOM) approach, quality factor (Q-factor) maximization, or by sweeping values for coil geometries. Four WPT systems for biomedical applications are implemented with inductive coupling. The thesis later presents an optimization technique for finding the maximum PTE of a range of frequencies and coil shapes through frequency, geometry and shape sweeping. Five optimized TX coil designs for different operating frequencies are fabricated for three shapes: square, hexagonal, and octagonal planar-spirals. The corresponding RX is implemented on polyimide tape with ink-jet-print (IJP) silver. At 80 MHz, the maximum measured PTE achieved is 2.781% at a 10 mm distance in the air for square planar-spiral coils.

[ES] La tesis que se presenta bajo el título Metodologías de transferencia mediante sistemas de impresión inkjet: Procesos para la creación gráfica digital, pretende mostrar desde una perspectiva conceptual y técnico-práctica la evolución en el desarrollo de procesos desde los sistemas de registro y reproducción electrónicos hasta las tecnologías de registro, producción y representación digital, mediante procesos híbridos, ampliando el campo para la creación de la gráfica digital especialmente con impresoras de inyección de tinta. Se analiza la situación contextual de la gráfica a través de un recorrido histórico que parte desde principios del siglo XX para comprender los cambios y planteamientos que se han producido en la concepción de la gráfica como un medio autosuficiente para la creación de obra de arte única. Además de la percepción de las imágenes a través de la tecnología y como esta ha repercutido en la reflexión de nuevos enfoques en el medio artístico. En este sentido, tratamos de conceptualizar el movimiento y la percepción que provoca el mundo digital sobre las imágenes a través de la transferencia, no solo como concepto que nos ayuda a comprender cómo influye la transmisión de códigos, sino también, como práctica artística para extraer y materializar el flujo digital, las imágenes intangibles y dotarlas de un estado háptico, convirtiéndolas en objetos físicos. Para dar corporeidad a las imágenes, en la investigación se propone una serie de procesos de transferencia realizados a partir de sistemas de impresión inkjet donde entran en juego factores como el soporte temporal, el medio reportador y el soporte definitivo, el cual se desvincula de la tradicionalidad gráfica, utilizando materiales diversos que aportan un valor añadido a la pieza. / [CA] La tesi que es presenta sota el títol Metodologies de transferència mitjançant sistemes d'impressió inkjet: Processos per a la creació gràfica digital, pretén mostrar des d'una perspectiva conceptual i tècnic-pràctica l'evolució en el desenvolupament de processos des dels sistemes de registre i reproducció electrònics fins a les tecnologies de registre, producció i representació digital, mitjançant processos híbrids, ampliant el camp per a la creació de la gràfica digital especialment amb impressores d'injecció de tinta. S'analitza la situació contextual de la gràfica a través d'un recorregut històric que parteix des de principis del segle XX per a comprendre els canvis i plantejaments que s'han produït en la concepció de la gràfica com un mitjà autosuficient per a la creació d'obra d'art única. A més de la percepció de les imatges a través de la tecnologia i com aquesta ha repercutit en la reflexió de nous enfocaments en el mitjà artístic. En aquest sentit, tractem de conceptualitzar el moviment i la percepció que provoca el món digital sobre les imatges a través de la transferència, no sols com a concepte que ens ajuda a comprendre com influeix la transmissió de codis, sinó també, com a pràctica artística per a extreure i materialitzar del flux digital, les imatges intangibles i dotar-les d'un estat hàptic, convertint-les en objectes físics. Per a donar corporeïtat a les imatges, en la investigació es proposa una sèrie de processos de transferència realitzats a partir de sistemes d'impressió inkjet on entren en joc factors com el suport temporal, el mig reportador i el suport definitiu, el qual es desvincula de la tradicionalitat gràfica, utilitzant materials diversos que aporten un valor afegit a la peça. / [EN] The thesis presented under the title Methodologies of transfer using inkjet printing systems: Processes for digital graphic creation, aims to show from a conceptual and technical-practical perspective the evolution in the development of processes from electronic recording and reproduction systems until digital recording, production and representation technologies, through hybrid processes, expanding the field for the creation of digital graphics. especially with inkjet printers. The contextual situation of graphics is analyzed through a historical journey that starts from the beginning of the 20th century to understand the changes and proposals that have occurred in the conception of graphics as a self-sufficient means for the creation of unique works of art. In addition to the perception of images through technology and how it has affected the reflection of new approaches in the artistic medium. These means that we try to conceptualize the movement and perception that the digital world provokes on images through transfer, not only as a concept that helps us understand how the transmission of codes influences, but also as an artistic practice to extract and materialize intangible images of the digital flow and endow them with a haptic state, turning them into physical objects. In order to give corporeality to the images, the research proposes a series of transfer processes carried out using inkjet printing systems where factors such as temporary support, informative support and definitive support come into play, which is detached from graphic traditionality, using different materials that provide added value to the piece. / Molina Guixot, C. (2023). Metodologías de transferencia mediante sistemas de impresión inkjet: Procesos para la creación gráfica digital [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/193072

<p>The 2020 pandemic emphasized the need for accessible and accurate point-of-care diagnostic tests. With the continued development of isothermal nucleic acid amplification tests, this can be achieved. A requirement of these tests includes heating and holding a specific temperature, in this case, 65C for 30 minutes, for amplification to occur. To achieve this, heaters often require external feedback to control the temperature; bringing up the device’s cost. Several self-regulating heaters have been made with materials having a positive thermal coefficient of resistance eliminating the need for complex circuitry. With this property, point-of-care diagnostic tests can be simplified and made more accessible. In this study, ink-based positive thermal coefficient of resistance heaters are developed and characterized using the scalable method of screen printing to achieve 65C and aid in the detection of SARS-CoV-2. Various curing methods and screen-printing parameters were evaluated to improve the stability and understanding of the reproducibility of the heaters. The longevity of the heaters was evaluated with oxidation studies and a COMSOL model was created to study the heat transfer within the device. Furthermore, the heaters were successfully implemented into a second-generation electronic point-of-care diagnostic device. Detection of SARS-CoV-2 using a self-regulating heater removes the need for complex circuitry, improving the accessibility of point-of-care tests with the potential to be expanded to a wide range of pathogen detection. </p>

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The increasing demand for digitalization has spurred the need for novel and sustainable designs of electronic devices like sensors. Advanced additive print technologies, organic inks, and bio-based substrates in device fabrication exhibit promising potential for reducing energy and raw material consumption, thereby alleviating environmental impacts. One such innovation is the novel method of laser graphitization in designing devices like printed humidity sensors. This study focuses on evaluating the environmental impacts of implementing this novel technique in the field of printed electronics. In particular, the thesis conducts a cradle-to-gate life cycle assessment (LCA) of producing a resistive-type humidity sensor from a forest-based wood ink using laser graphitization. The sensor is based on the design that was demonstrated in the lab facilities at the Research Institutes of Sweden (RISE), Norrköping. The assessment is at a lab-scale production of making 1mm2 area of a laser-induced graphitized (LIG) sensor, excluding usage, disposal, or recycling phases. The results highlight impacts from electricity usage as the primary contributor to the overall environmental impacts, across the production process, followed by the impacts from material usage. The impact share distribution from these two hotspots identifies opportunities in the process that need to be prioritized for immediate actions. Sensitivity analyses varying the sensor layer thickness and the electricity mix of the laboratory facilities reveal insightful impact trends. The results from scenario analyses show the LIG sensor to have much lower environmental impacts than that of a sensor with silver electrodes and carbon-based sensing ink. They also show potential for achieving economies of scale from the mass production of LIG sensors. The data inventory for the processes and components of the sensor stands as a crucial part of this study, relying heavily on literature, assumptions, and proxy data. While these may reveal some uncertainties and limitations, the study nonetheless, serves as an important reference for future research concerning similar databases and a cradle-to-grave LCA of the sensor. / Den ökade efterfrågan för digitalisering har skapat behov av nya och hållbara designs av elektroniska enheter som sensorer. Avancerade lager printteknologier, organiskt bläck och biobaserat substrat i enhetstillverkning visar lovande potential för att reducera energi och rå materielkonsumtion och därmed minskning av miljöpåverkan. En sådan innovation är den nya metoden av lasergrafitisering i designenheter som printad fuktighetssensor. Denna studie har som fokus att utvärdera miljöpåverkan av ny teknik inom området tryckt elektronik. I synnerhet ska avhandlingen göra en livscykelanalys (LCA), från råvaruutvinning till slutprodukt av att producera en resistent fuktsensor från ett skogsbaserat träbläck genom lasergrafitisering. Sensorn är baserad på en design som var demonstrerad i en labbanläggning hos forskningsinstitutet RISE i Norrköping. Forskningen är analysen av laboratorieskalad produktion av 1mm2 lasergrafitiserad sensoryta, exklusive användning, bortskaffande och återvinningsfaser. Resultaten lyfter fram påverkan från elektronisk användning som den primära bidragaren till övergripande miljöpåverkan över hela produktionsprocessen, följd av påverkan från materiell användning. Påverkan från dessa två hotspots uppmärksamgör möjligheter i processen som är av prioritet för omedelbart åtgärdande. Känslighetsanalyser av de varierande sensorskiktens tjockhet och elektronisk mix i laboratoriums faciliteten, påvisar insiktsfulla påverkanstrender. Resultaten från scenarioanalyser visar att LIG sensorer har mycket lägre miljöpåverkan än sensorer med silverelektroner och kolbaserat avläsningsbläck. De visar också potential för att uppnå ekonomisk skalbarhet för massproducering av LIG-sensorer. Datalagring för processerna och komponenterna av sensorn står som kritisk del av studien, med en tung tillit på litteratur, antaganden och proxydata. Då dessa faktorer kan påvisa några osäkerheter och begränsningar så bidrar studien ändå som en viktig referens för framtida forskning berörande liknande databaser och en LCA från råvaruutvinning till sluthanteringsfasen av sensorn.

Iridescence is the property that makes colors vary by angle of observation. Technology has made it possible to print with ink that has this anisotropic property. The ink that is used contains microparticles and therefore only specific printing methods can be used, for example screen printing. This comes with new demands on halftones, due to its procedure; dots cannot be too small, and keeping structures should be prioritized. To minimize costs and time, prints should be simulated before sending an order. In this thesis, different methods to halftone for screen printing with iridescent ink are developed. Three existing methods are compared to methods that are developed for this specific cause. The result is presented as a 2D-mask and as an interactive 3D-simulation, using data measured from real ink. Also, properties of iridescence are analyzed to separate it from diffuse colors. An OpenGL simulation tool was developed for simulating halftones on 3D-models. The ink reflectance spectra are represented by polynomials that take as input the wavelength and observation angle. Given an observation angle, a spectrum can be found, which can be converted to RGB and set as the output color in the fragment shader. The program uses an RGB-mask which is the combined masks of the halftone. This is loaded as a texture which indicates what polynomial to use. There is no perfect method that works for all types of images. Images that contain colors similar to the inks benefit from morphological halftoning (enhanced structures) for iridescent areas, or foreground, and hatching (an angle dependant grid pattern) for diffuse areas, or background. Other images, that contain mixed colors as cyan, yellow or magenta, benefit froma hue separation error diffusion, where masks are created by thresholding the hue where the mixed colors are error diffused.The actual prints confirmed the hypothesis that tone reproduction can be of lower priority while structure and depth preservance should be highly prioritized. Iridescent colors can be separated from diffuse colors by thresholding the saturation combined with value, or the lightness of the Lab-representation

Les dispositifs optoélectroniques sont devenus un élément essentiel de la technologie moderne visant à exploiter des applications de niche pour l'électronique flexible à base de composés organiques. Jusqu'à présent, les films minces préparés à partir de composés polymères conjugués ont été les principaux concurrents pour les dispositifs optoélectroniques organiques. Avec l'apparition de nouvelles méthodes de mise en œuvre et de nouveaux besoins électroniques, les méthodes de fabrication additive des matériaux optoélectroniques suscitent de plus en plus d'intérêt. Malgré l'intérêt croissant et la variété des méthodes de mise en œuvre tridimensionnelles, on comprend encore mal l'impact de la technique de mise en œuvre sur l'organisation moléculaire des échantillons. Ici, une étude est présentée impliquant l’impression 3D assistée par évaporation de solvant et le poly(3-hexylthiophène) (P3HT) qui est bien décrit dans la littérature, et, dans ce cas-ci, mélangé à diverses matrices thermoplastiques. Dans un premier temps, les matrices thermoplastiques employées, i.e. le polystyrène (PS), le polypropylène carbonate (PPC), le polyméthacrylate de méthyle (PMMA) et le polyoxyéthylène (PEO) sont évaluées en fonction de leurs propriétés rhéologiques et de leur imprimabilité en 3D, qui ne sont que très peu affectées par l'introduction du P3HT. Par la suite, le P3HT à régiorégularité élevée et faible est mélangé dans chacune des matrices thermoplastiques. L'organisation moléculaire des deux composantes dans les architectures imprimées a été évaluée par des techniques de spectroscopie UV-visible et de fluorescence. Les phases en présence ont été analysées à l'aide d’analyse calorimétrique différentielle à balayage, de microscopie optique polarisée et de diffraction des rayons X, ce qui a également permis d'analyser l'état d'agrégation du P3HT par rapport à celui retrouvé dans les films minces. Il est intéressant de noter que les propriétés optiques montrent peu ou pas de différence entre les architectures 3D et les films minces, ce qui indique vraisemblablement que l'efficacité d'un dispositif optoélectronique imprimé en 3D ne serait pas affectée par l’impression 3D assistée par évaporation de solvant. Cette étude pourrait permettre de mieux comprendre comment il serait possible de mettre au point des dispositifs optoélectroniques, y compris des photoconducteurs, des photovoltaïques organiques, des transistors à effet de champ organiques, etc. à l’aide de techniques de fabrication additive, ce qui ouvrira la voie à une nouvelle ère en électronique organique imprimée en trois dimensions. / Optoelectronic devices have become a staple in modern day technology which aims to transition to flexible electronics that are developed from organic compounds. To date, 2-dimensional films of conjugated polymer compounds have been the main contender for organic optoelectronic devices. As new processing methods and electronic needs become present in the modern day, a focus on 3-dimensional processing methods of optoelectronic materials have become increasingly of interest. With the increasing interest and variety of 3-dimensional processing methods, there is little understanding of how the processing technique molecularly affects the final product. Herein is presented a study on the extrusion-based, direct-ink writing of the well understood poly(3-hexylthiophene-2,5-diyl) (P3HT) blended into a variety of thermoplastic matrices. Initially the pristine thermoplastics of polystyrene (PS), poly(propylene carbonate) (PPC), poly(methyl methacrylate) (PMMA), and poly(ethylene oxide) (PEO) were evaluated based on their rheological and printable properties which are negligibly affected by the introduction of P3HT. Subsequently, after the blending of both high and low regioregular P3HT into each of the thermoplastic matrices, the printed architectures were further analyzed by X-Ray diffraction, UV-vis, and fluorescence techniques to assess the aggregation state of P3HT in comparison to 2-dimensional processed films. Interestingly, the electronic properties show little to no difference between 3-dimensional architectures and 2-dimensional films, which presumably indicates that the efficiency would not be affected by the direct-ink writing technique. This study could contribute to the beginning of producing optoelectronic devices, including photoconductors, organic photovoltaic and organic field effect transistors, in 3-dimensions resulting in a new age of electronics.

Environmental stresses arising from temperature and moisture changes, and/or other aggressive fluid ingressions can degrade the mechanical properties of the adhesive, as well as the integrity of an adhesive interface with a substrate. Therefore such disruptions can significantly reduce the lifetime and durability of an adhesive joint.1-4 In this research, the durability of certain epoxy adhesive joints and coatings were characterized using a fracture mechanics approach and also by constant frequency impedance spectroscopy. The shaft-loaded blister test (SLBT) was utilized to measure the strain energy release rate (G) or adhesive fracture energy of a pressure sensitive adhesive tape. In this study, support for the value of the SLBT fracture mechanics approach was obtained. The SLBT was then used to investigate the effects of relative humidity on a model epoxy bonded to silicon oxide. Lastly, the effects of water and temperature on the adhesion of a commercial filled epoxy bonded to silicon oxide was characterized and interpreted. A novel impedance sensor for investigating adhesion was developed in a collaborative effort between Virginia Tech and Hewlett-Packard. Utilizing the technique of constant frequency impedance spectroscopy, the distribution and transport of fluids at the interface of adhesive joints was measured. A broad spectrum of adhesives was tested. In addition, the effects of hygroscopic cycling on the durability of adhesive coatings were measured for the commercial filled epoxy using the device. Lastly, recommended modifications of the experimental set-up with the new sensor are proposed to improve the technique. / Ph. D.