Tesi sul tema "Electronic screen"

Printed electronics (PE) is a set of printing methods used to create electrical devices on various substrates. Printing typically uses common printing equipment suitable for defining patterns on material, such as screen printing, flexography, gravure, offset lithography, and inkjet. Electrically functional, electronic or optical inks are deposited on the substrate, creating active or passive devices. PE offers a great advantage when compared to traditional processes or microelectronics due to its versatility, low manufacturing cost and the possibility of generating flexible circuit componentsi. Furthermore, these techniques are suitable for roll-to-roll processes and open the possibility for printing large areas and in a large-scale production. . The selection of the printing technique is crucial to achieve a good result and it will largely depend on both, the material needed and dimensional and functional requirements pursued. Each technology offers different possibilities in terms of resolution, complexity, versatility, speed, layers thickness, materials, reliability and scalability. This work aims to dig deeper into two of the main techniques in the world of printed electronics: screen printing and inkjet printing for different applications and for the manufacturing of different devices. In addition, the capabilities of a technology that is currently in growing development (inkjet) are analyzed in comparison with the mature screen printing technique to give a wider insight of the advantages and limitations that this technology offers. The totally knowledge in this technique is still in progress and it arises to be a trend in technological and scientific aspects due to the barely availability of functional materialsii and the difficulties in achieving a precise control on the drop formation and its interaction in the final system. A better understanding of these technological issues, as well as the approaching to current difficulties in electronic applications is accomplished in this thesis. Up-to-date issues as the reliability of flexible resistive gas sensors, solution-based synthesis of absorber layers in thin film solar cells and the tuning and area reducing for inductors in RF applications are tackled. The main objective in this thesis arises from the need of expanding the knowledge on inkjet printing by exploring affordable new possibilities, taking as starting point the previous knowledge of screen printing. To pursue this goal, the comparison between SP and IP is presented along the thesis. The framework of this thesis is not solely an overview of the development of functional materials for both techniques, but also the investigation of its final implementation reliability in several devices for different electronic applications. The structure of this thesis dissertation can be divided in two well defined blocks. In chapter 2 and 3, both printing techniques are explained in detail, while in Chapter 4, 5 and 6, the potential of both technologies are studied for different electronic applications by means of the fabrication and characterization of different devices. In chapter 2, the main topic is the analysis of the inkjet printing technique. This chapter follows the attainment of two different objectives: the establishment of a quality evaluation guideline for any inkjet ink and as example of it, the formulation of our own silver ink developed in our laboratory. In this sense, the most important properties for the functional materials which should be under control during its formulation are reviewed; as well as the fundamentals and main parameters during the printing process, which affect the outcome quality. Instead, in chapter 3, the fundamentals of screen printing technique are quickly overviewed due to the consolidation of the technique knowledge and the previous studies on it done in the field, and specifically at FAE Company. In the second block of this thesis, the description of the printing techniques leads to the implementation of both, inkjet and screen printing, in different electronic fields. The chapters involving this block are focused in the printing step during its fabrication, the printing and functional material quality characterization, and the influence of this printing step in the functional performance of the devices. Chapter 4 is a comparison between low-cost flexible resistive sensor platforms with heater fabricated by both, SP and IP techniques. The performance of these sensor platforms was checked by long-term characterization and aging tests to identify the causes of the device failure. Chemical degradation of silver is observed in SP-devices due to the flake-like morphology of the deposits but not in the smooth sintered silver tracks deposited by IP. However, the IP very thin film promotes failure by hot spot phenomena. Design improvements are, hence, implemented to overcome the drawbacks of silver corrosion and power consumption. The final devices turned to be sturdy, wearable and reliable gas sensor platforms. In Chapter 5, IP is implemented in the step of the absorber layer synthesis for the fabrication of kesterite thin film solar cells. Copper-Zinc-Tin-Sulfur (CZTS) precursor ink is formulated and optimized for the enhancement of the solar cell performance. The influence of the formulation and the printing process is analyzed. Finally, the thickness of the deposited precursor was modified until obtained a cell with 6.55% efficiency, the higher efficiency reported with this absorber type using IP as deposition method. In the last chapter, Chapter 6, spiral inductors are fabricating using the two printing technologies in LTCC (low-temperature-cofired-ceramics). IP, although turning out to be a suitable technology for enhancing the accuracy of narrower tracks than SP and thus, for increasing the number of turns within a concrete area, presents difficulties to achieve a certain value in electrical conductivity due to the deposition of very thin conductor layers. For this reason, in this part of the thesis, a combination of IP with electroless copper deposition is used to overcome this limitation and to develop equivalent performances using SP and IP devices.
La electrónica impresa permite la impresión de dispositivos electrónicos ofreciendo una gran ventaja en comparación con procesos tradicionales o microelectrónica debido a su versatilidad, bajo coste de producción y posibilidad de generar circuitos flexibles. La selección del método de impresión es crucial a la hora de alcanzar un buen resultado y depende de los materiales necesarios y de los requerimientos dimensionales y funcionales. En esta tesis, la serigrafía, una técnica de impresión fiable y consolidada en la industria desde hace años, es comparada con la inyección de tinta (inkjet), que aún muestra un gran desafío en cuanto a rendimiento y reproducibilidad. Cada tecnología ofrece posibilidades diferentes en complejidad, resolución, grosor de capas y materiales. En la primera parte de la tesis se describen la inyección de tinta y la serigrafía en términos de fundamentos, parámetros y formulación de materiales. En la segunda parte, el potencial de ambas tecnologías se ha estudiado en diferentes escenarios mediante la fabricación de diversos dispositivos electrónicos. En el estudio de la fiabilidad y robustez de plataformas sensoras flexibles se ha encontrado una relación directa entre la morfología de la plata depositada y su causa de fallo en funcionamiento prolongado. La sinterización de las nanoparticulas depositadas por inkjet forma una capa lisa y con poca porosidad que evita parcialmente la corrosión, a diferencia de la pasta de plata impresa por serigrafía. Sin embargo, su bajo provoca defectos puntuales que puede causar puntos calientes. También, inkjet se ha empleado para la síntesis de precursores de la capa absorbente para celdas solares de capa fina. Se ha formulado una tinta de precursores de cobre, zinc, estaño y azufre (CZTS) para la formación de kesterita obteniéndose celdas de 6.55% de eficiencia, siendo la más alta reportada hasta la fecha utilizando este tipo de absorbente y tecnología. Sin embargo, en aplicaciones donde la conductividad es crucial para altas prestaciones, como en radiofrecuencia, queda patente la desventaja del inkjet sobre la serigrafía, donde su escaso grosor de capa es un claro hándicap para la obtención de conductividades elevadas. Dicho factor limitante es abordado con la combinación de la inyección de tinta con la deposición química (electroless) de níquel y cobre, consiguiéndose inductores equivalentes a los serigrafiados.

This thesis investigates paper-based electronics in terms of various substrates, fabrication methods and example devices, including touch sensors and microwave resonators. The term ‘paper’ is very broad and covers a wide range of substrates. A decision matrix has been created to determine the optimum paper for an application, based on a range of properties. Thermal evaporation and screen printing are compared for their use as fabrication methods for paper-based electronics and a second decision matrix has been compiled. Based on these decision matrices, screen printing onto a thicker matt paper was determined to be optimal. The printing process was further optimised to achieve the best results from the in-house process. Using this well-developed screen-printing method, passive components (including inductors and interdigitated capacitive touch sensors) were fabricated and found to be comparable with state-of-the- art results reported in the literature. Measurements from the touch pads were compared to modelling, with little variation between the two, and were confirmed to work under a wide range of conditions, showing that they are compatible with any user. The microwave characteristics, up to 3GHz, of both the chosen substrate and silver-flake ink were investigated through production of screen-printed transmission lines. These characteristics were then used to create microwave resonators. The frequency range is important for applications as the industrial, scientific and medical radio band (ISM band) lies between 2.45 and 2.55 GHz which includes Wi-Fi and Bluetooth. Initially, stub resonators were considered to determine the cause of differences between theoretical and measured results. Then spiral defected ground structures were made, with multiple resonances, and sensitivity to touch and humidity demonstrated. As paper is hygroscopic, the effect of humidity on paper-based electronics is of key importance. This has been considered for all the devices fabricated in this work and it has been determined that the change in permittivity of the substrate, as a result of absorbed water within paper, is the most dominant factor.

This thesis describes the development of printed wearable electrode networks on textiles for monitoring human biopotentials from the skin surface. The aim was to fabricate garments to monitor human biopotentials, such as an electrocardiogram (ECG), on a long term basis. A literature review was carried out to examine fabrication methods for wearable electrode networks on textile and screen printing is selected for this work. Several conductive and insulating screen printable pastes were then evaluated for this application and suitable pastes were selected. Screen printing was used to create networks of conductive tracks on the surface of woven textiles. These networks connect electrodes at different sites to electronics at a central location. The conductive tracks are composed of a silver polymer layer with thickness 5-10μm entirely encapsulated in polyurethane. The durability of these printed conductive tracks is investigated with cyclic stress and washing machine tests. A significant improvement in the durability of these tracks is achieved by using two different polyurethane pastes and optimising the screen printed layer structure. Tracks that can reliably endure 10 typical domestic machine washes without breaking are demonstrated. Carbon loaded silicone rubber is stencil printed to form electrodes on exposed conductive pads at the terminations of screen printed conductive tracks. The carbon loaded rubber formulation is optimised to provide electrodes with low resistivity, low surface energy and high flexibility. By using stencil printing rather than screen printing, the thickness of the electrodes is increased, causing them to protrude from the textile surface, which is useful in ensuring stable electrode-skin contact. Passive and active electrodes are fabricated on woven textiles using screen and stencil printing, and their performance is evaluated. The passive electrodes have issues with DC instability, but have suitable performance for some electromyography tasks and basic heart rate monitoring. The active electrodes show comparable performance with the gold standard, commercial Ag/AgCl electrodes. The printed textile electrode networks are demonstrated in four applications: a one-lead bipolar heart monitoring belt, a Frank configuration vector-cardiogram monitoring vest, a headband as an electromyographic (EMG) and electrooculographic (EOG) computer interface, and an armband used to examine electromyographic activity in the upper arm. Screen printing on textiles is shown to be a low-cost alternative fabrication process for durable wearable electrode networks on textiles, capable of providing high signal quality. These printed textile electrode networks are shown to be applicable to ambulatory monitoring, to reduce the associated cost and discomfort, and in hospitals and research to reduce electrode setup time.

In the development of inks for printed electronics, it is important to understand the behaviour of the functional inks and more especially their rheology and surface properties. This project emphasises the importance of ink characterization by performing rheological tests on silicon nanoparticle based inks that are used in the screen printing of electronic devices. The inks were characterized for linear viscoelastic behaviour, flow behaviour, change in properties with angular frequency, as well as thixotropic behaviour. All showed shear thinning, with the more dilute inks showing a power law (Ostwald / de Waele model) behaviour dependence of complex viscosity on angular frequency. The flow behaviour of the inks was also seen to follow a Windhab model. The printability of the inks primarily depends on the shear-dependent viscosity as highly viscous and dilute inks do not produce good printed structures. The printed layers showed electrical and optical activity.

Harmony is a major theme in Chinese culture. It is reflected in many forms, e.g. painting and garden design. However, calligraphy gives a straight forward insight into harmony in two dimensions. The main hypothesis was that the principles for building a harmonious calligraphic character could be converted from holistic to deductive and computable ones. These could then be applied to the design of harmonious screen interfaces, which would give visual pleasure. The first aim was to investigate and discover the quantifiable features of harmony in Chinese regular script calligraphy. Calligraphy has been associated in China with harmony and elegance for over 1500 years. There are features that are commonly accepted to establish harmony which can be quantified. However, the principles of Chinese calligraphy are embedded within Chinese culture. Direct translation does not convey the meaning. An extensive study was made of the literature on Chinese calligraphy and a practical exploration of characters was made. This resulted in a small number of principles which were needed to be satisfied for the character to appear harmonious. These were tested on several groups of participants. These principles were then converted into a mathematical form for Chinese regular script calligraphy, and for application to harmonious screen interface design. The mathematical forms were then tested on both Chinese regular script calligraphy and also on interface designs with groups of participants. Finally, an application for comparing harmony in Chinese calligraphic characters and interface designs was created. The “Harmony” application can be used to calculate how a Chinese calligraphic character or an interface design satisfies the principles of harmony and it can give an indication of how harmonious they are.

This dissertation consists of 3 essays that examine the impact of electronic screen trading in futures markets. The research provides empirical evidence on increasingly significant issues given the rapid global advances in technology used in securities markets. Each essay addresses the scarcity of conclusive research in order to aid researchers, regulators, exchange policy makers and systems builders as they confront issues related to electronic trading systems.

In this thesis, two methods of creating multi-layer porous films for DSSCs are examined. They have been designed as possible alternatives for screen printing in laboratory settings. The same precursor chemicals used for screen printing are employed in both the alternative methods, which are designated multi-layer doctor-blading and stamping. Both alternatives are simple and inexpensive, costing $0.86 and $0.89 per DSSC, respectively. Multi-layer doctor bladed cells can be made with up to three layers, while stamped cells can be made with up to eight. The cells produced by these two methods are compared to a sample screen printed cell, with mixed results. The multi-layer doctor bladed cells exhibit lower current densities than a screen printed cell, 68.0 A/m2 compared to 68.9 A/m2. The best performing stamped cell demonstrates a higher current density than the screen printed reference, reaching 82.7 A/m2. It also has a slightly higher efficiency. However, the results from the stamped cells are inconsistent. In order for it to truly become an effective method for creating DSSCs in laboratory settings, the source of this variation must be found and standardized.
Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering.

Thesis (PhD)--Stellenbosch University, 1993
ENGLISH ABSTRACT: An extensive literature study revealed numerous Jauman absorber examples with reasonable absorption properties. Unfortunately, tractable and detailed design techniques were found to be scarce, and often only applicable to absorbers with two or three layers. The research described in this report was therefore aimed at, and culminated in, general design methods for multilayered electric screen J auman absorbers. As a starting point, the synthesis problem is formulated by idealizing the spacers (assumed lossless and commensurate) and resistive sheets (assumed to have zero thickness), and by considering the absorption of a normally incident plane wave. An equivalent circuit model is derived, using the analogy between plane waves in stratified media, and guided waves in TEM transmission lines. The network is analyzed using Richard's frequency surrogate, S = tanh(s = cr +jw), and concise equations and algorithms are presented for symbolic and numerical analysis. Maximum bandwidth synthesis of the classic one-layer absorber, or Salisbury screen, proved to be simple, clearly illustrates the analytic approach, and apparently has not been published before. The two-layer absorber was also found to be algebraically simple enough to be synthesized in closed form, is dealt with comprehensively, and the treatment consolidates and formalizes many of the design techniques available in the literature. Networks comprising commensurate transmission lines and conductances have been investigated by Richardsl , but unfortunately the topology-driven realizability constraints on the input impedance of the Jauman network is only dealt with briefly. Fruitless investigations by the author showed this to be a formidable problem, and as a result the research concentrated on tractable and iterative synthesis algorithms for multilayered absorbers, instead of formal filter synthesis techniques. These algorithms may be summarized as follows: • A key concept in the multilayer zero-placement synthesis methods that will be presented, is the ability to physically realize a given set of reflection coefficientzeros. This involves solving a set of highly non-linear equations, and a gradientmethod iterative algorithm has been developed to achieve this . • The first application of the aforementioned algorithm is to synthesize all reflection zeros at S →∞, thereby obtaining a maximally flat reflection coefficient magnitude response. Stable and rapid convergence was found for up to at least 20 layers, thereby extending the two- and three-layer algebraic solutions available in the literature. It was found that a stringent restriction exists on the maximum dielectric constant (Er) of the spacers, thereby limiting the practical implementation of these solutions . • Through judicious manipulation of reflection zeros at distinct physical frequencies, an equiripple absorption response may be obtained. An elegant algorithm is presented to facilitate this, and it was found that these solutions represent substantial improvements over examples available in the literature. Restrictions still apply to the spacer Er, but these are more relaxed and practical equiripple absorbers are possible. In addition, the spread in sheet resistivities is much smaller than in comparable maximally flat solutions. • Numerical searches indicated that the aforementioned equiripple responses are very close to, but not absolutely optimal, in the sense of maximum bandwidth. The small bandwidth and/or absorption improvements that were found were almost negligible from a practical viewpoint, but the optimal synthesis problem is academically very important. Through use of the general Chebyshev approximation method, an algorithm is developed which finds the local optimal response in the vicinity of such a parent equiripple solution. Although it might be tempting to classify the algorithm as a brute force method, it will be shown that this is not the case, and that its solutions provide the answer to the fundamental and unsolved optimal design problem. These algorithms have been implemented, and tables of resistive sheet values are presented for N up to 8, a range of Er values corresponding to low loss foams, and for various absorption levels.
AFRIKAANSE OPSOMMING: geen opsomming

Do inventions that exist only on paper have less credibility than functional technologies? How has the meaning and significance of audiovisual media and technology changed over time? This dissertation examines historiography and methodology for media history, arguing for an interdisciplinary approach. It addresses methodological issues in media history—media in transition, media archaeology, and film history—through an examination of television’s speculative era. It tackles moving-image history through an historical investigation of Victorian and Machine age “television”. Because the concept and terminology of “television” changed dramatically during this period, I use the phrases “distant electric vision” and “seeing by electricity,” to define the concept of electric and electronic moving-image technology. By identifying manifestations of “television” before functional models existed, this dissertation examines the ways in which a modern concept of moving-image technology came into existence. Engineers and inventors, as well as audiences and journalists contributed to the construction of “television.” Newspaper announcements, editorial columns, letters to the editor, rumors and satires circulated. Victorian-era readers, writers and inventors pictured “seeing by electricity” to do for the eye what the telephone had done for the ear, bringing people closer together though separated by great distances. In contrast, early twentieth-century Machine-age engineers placed more emphasis on systems, communication, design, and picture quality. Developments in the 1920s with complex systems and electronics made “distant electric vision” a reality. This dissertation identifies several shifts that took place during television’s speculative era from the Victorian “annihilation of space” to Machine-Age systems engineering. Journalists, readers, and engineers all play a part in the rhetoric of innovation. From the Victorian era to the Machine age, the educational function of popular science and the role of audiences in constructing meaning and value for new technologies remain relatively consistent. I offer several case studies, including Thomas Edison’s inventions, illuminating engineering, and Bell Labs experiments with television. This dissertation argues that modern television design relies on the ability of the technology to make an unnatural experience seem as effortless as possible. Ultimately, it advocates for an expanded definition of media and technology, along with an historical emphasis on context.

A sedentary lifestyle can induce health related problems including pressure ulcers. Pro­longed sitting inadequacies constitute a risk for pressure ulcer to many individuals, in particular people with disabilities and re­duced mobility. The measurement of distributed pressure and detection of irregular sitting postures are essential in prevention of the risk of developing pres­sure ulcers. In this thesis, a screen-printed pressure sensor for a large area is presented, with the objective of measuring the distributed pressure of a seated per­son in a wheelchair. The conductors and interdigital patterns are printed with silver-based ink. A blend of a non-conductive and a low resis­tive ink is used for customized resistance for an optimal sensing range of the pressure sensor. The effect of moisture and temper­ature are realized in an environment chamber. For characterization, other key performance tests such as repeatability, drift and flexibility are carried out. The surface morphology is carried out for structural analysis of printed samples. The sensor data is acquired and processed using an 8-bit ATmega-2560 micro­controller and wirelessly transmitted to a PC for post-processing, storage and analysis. For real-time data presentation of dis­tributed pressure points, a GUI has been developed to display the values ob­tained from the large area sensor. The detection of four sit­ting pos­tures; forward leaning, backward leaning, left leaning and right leaning along with a normal sitting posture is attained. An analysis for stretchable printed tracks has been conducted to investigate the changes in electrical resistance using elon­ga­tion tests, surface morphology and EDS. The optimal curing time and tem­per­ature were investigated to manufacture stretchable conductive tracks. In summary, the contributions in this thesis provides an effective approach regarding pressure distribution measurement and recognizing irregular sitting postures for wheelchair users.

Vid tidpunkten för framläggningen av avhandlingen var följande delarbete opublicerat: delarbete 3 (accepterat).

At the time of the defence the following paper was unpublished: paper 3 (accepted).

This thesis presents a new approach for fabricating free standing structures on flexible substrates using the screen printing technique. The research addresses electronic textile applications and is intended to provide a new method for realising sensors and complex structures on fabrics. Conventional smart fabric fabrication methods, such as weaving and knitting, are only able to achieve planar structures with limited functionality. Packaged discrete sensors can also be attached directly to fabrics but this approach is unreliable and unsuitable for mass production. The reported materials and the fabrication processes enable free standing structures to be formed by printing functional layers directly on top of the fabric. This reduces the fabrication complexity and increases wearer comfort and the flexibility of the fabric. This research details an investigation into sacrificial materials suitable for use on fabrics. A plastic crystalline material (Trimetlylolethane (TME)) was identified as an appropriate sacrificial material because it sublimates which reduces the chance of stiction occurring. A screen printable TME paste has been achieved by dissolving TME powder in a solvent mixture of cyclohexanol (CH) and propylene glycol (PG). The TME sacrificial paste can be cured at 85 oC for 5 minutes providing a solid foundation for subsequent printed layers. This sacrificial layer can be removed in 30 minutes at 150 oC leaving no residue. EFV4/4965 UV curable dielectric material was identified as an appropriate structural material for use with TME. The feasibility of the sacrificial and structural materials has been demonstrated by the fabrication of free standing cantilevers and microfluidic pumps on fabrics and flexible plastic films. Printed cantilevers, with capacitive and piezoelectric sensing mechanisms, have been demonstrated as human motion sensors. A printed microfluidic pump with a maximum pumping rate of 68 μL/min at 3 kHz has also been demonstrated. Both the cantilever and micropump have been demonstrated, for the first time, on fabrics and polyimide substrates, respectively.

The problem with e-texts are related to the way texts are displayed on a screen, with multiple and different aspects that affect legibility, making readers prefer to read a paper format rather than e-resources. This research describes the factors that affect the legibility of online texts aimed at obtaining a better understanding of the usability of electronic Arabic texts for learning purposes within the field of electronic reading; mainly reading Arabic texts for students aged 9 to 13. This study sets out three particular aims: (1) building a reading strategy for Arabic schoolbook in both formats electronic and paper format based on users’ cognitive and behavioural processes; (2) defining the influence of three typographical variables that affect reading Arabic texts on a screen (font size, font-type and line length); and (3) studying the efficiency of reading Arabic texts and the related factors impacting the efficiency of reading and comprehension. Based on the nature of the research questions and objectives, positivism and phenomenology are adopted as the underlying philosophy for this research. The empirical research was divided into three phases; the first phase focused on collecting data about using the internet among students in primary schools by means of a questionnaire. This has helped in the selection of samples and determined the extent of the students’ reluctance to read from a screen. The second phase was to investigate the reading process of school book in two formats [ paper and electronic format] to build reading model based on users’ cognitive and behavioural processes. The third phase was to examine the factors that affect negatively the usability of electronic texts by examining three issues: font size [10, 14, 16 and 18], font type [Arabic traditional, Arial, Times New Roman, Simplified Arabic, and Courier New], and line length [single column and double columns]. Observation was applied as a tool to collect the data. The study has made a significant contribution to the understanding of electronic reading of Arabic language. This contribution addressed five aspects: (1) Two models of reading process for schoolbook using Arabic language were built according to users’ interaction with the school textbook in two formats ( electronic and paper). These models will not only help define the interaction amongst users and e-books, but will also help designers to understand user behaviour of e-books and thereby to establish the most appropriate functions/features when building an e-book interface. (2) Identify the optimal font size for reading an Arabic script from screen by children aged 9 to 13. (3) Based on collecting data from experiments (2) and (3) and comparing this date with other researches that have done in the same field, new model explains the interaction between three topographical variables [font size, font type and line length] and their relationships with independent variables were provided. (4) Test a new display technique to improve the legibility of reading Arabic online texts by using colour to increase the ability to focus vision when moving from one line to another so as to improve the screen display. And (5) according to quantitative and qualitative several of the rules were recommended for designers and educators to follow when designing and presenting Arabic text on screen. On the other hand, some recommendations for future research have been derived from this thesis, such as the following. (1) Investigating the effect of the colour factor on improving the legibility of Arabic texts on screen for children, e.g. using different colours to distinguish between dots and vowels. (2) Exploring and developing an e-reading model based on all the factors recorded in the empirical studies in the reading field which will lead to building a theory on e- reading. (3) Investigating the influence of a variable effect reading process and the variables that have a positive or negative impact on it. (4) Applying a model that used colour to increase the ability to focus using different age-range and type of information such as journals or books.

Science fiction has long promised the digitalization of books. Characters in films and television routinely check their palm-sized (or smaller) electronic displays for fast-scrolling information. However, this very technology, increasingly prevalent in today's world, has not been embraced universally. While the convenience of pocket-sized information pieces has the techno-savvy entranced, the general public still greets the advent of the e-book with a curious reluctance. This lack of enthusiasm seems strange in the face of the many advantages offered by the new medium - vastly superior storage capacity, searchability, portability, lower cost, and instantaneous access. This dissertation addresses the need for research examining the reading comprehension and the role emotional response plays in the perceived performance on e-document formats as compared to traditional paper format. This study compares the relative reading comprehension on three formats (Kindle, iTouch, and paper) and examines the relationship of subject's emotional response and relative technology exposure as factors that affect how the subject perceives they have performed on those formats. This study demonstrates that, for basic reading comprehension, the medium does not matter. Furthermore, it shows that, the more uncomfortable a person is with technology and expertise in the requested task (in this case, reading), the more they cling to the belief that they will do better on traditional (paper) media - regardless of how well they actually do.

Only recently has our perception of the computer, now a familiar and ubiquitous element of everyday life, changed from seeing it as a mere tool to regarding it as a medium for creative expression. Computer technologies such as multimedia and hypertext applications have sparked an active critical debate not only about the future of the book format, ("the late age of print" {Bolter} is only one term used to describe the shift away from traditional print media to new forms of electronic communication) but also about the future of literature. Hypertext Fiction is the most prominent of proposed electronic literary forms and strong claims have been made about it: it will radically alter concepts of text, author and reader, enable forms of non-linear writing closer to the associative working of the mind, and make possible reader interaction with the text on a level impossible in printed text. So far the debate that has attempted to put hypertext fiction into a historical perspective has linked it to two developments. Firstly the developments in computer technology that made hypertext not only possible but also widely accessible and secondly a tradition of postmodern theory, where characteristics attributed to hypertext echo concepts of fragmentation, multiplicity and instability that theorists like Barthes and Derrida have formulated previously and that have led to the notion of hypertext as an "authentic, yet functional postmodern form" {Roberts} A third element that is not generally subject to critical evaluation is the practice of (post)modern writing in which a number of authors consciously break with the linearity of print conventions in favour for a more fragmented narrative and presentation as well as actively inviting the reader's participation in what Barthes calls "writerly" text. There are two reasons why these "proto-hypertexts" have been widely ignored or dismissed: Hypertext is still widely define as exclusive to the electronic realm and is furthermore generally perceived in oppositional pairs in contrast to print, i.e. non-linear vs. linear and interactive vs. passive, which conceptually does not leave room for a study of an "evolution" out of existing forms of writing practice. By examining hypertext fiction in a context of print experiments (Cortazar, Borges, B.S. Johnson, Andreas Okopenko, Raymond Queneau, Miroslav Pavic, Italo Calvino) and also in a context of other forms of digital literary experimentation (collaborative projects and computer-generated writing), this thesis aims to, on a diachronic level, reincorporate hypertext fiction into an evolutionary (though radical) literary tradition and examines the manner in which concepts which originated in this tradition have been taken over often very literally and without much redefinition. On the a-historical, synchronic level, this study explores some of the possible formats for literature in the new electronic textual media: hypertext fiction, collaborative writing projects, computer-generated writing and the different challenges these present to our understanding ofliterature. After an introduction in Chapter 1, Chapter 2 and 3 discuss two of the keywords of hypertext theory, its "grand narratives' (non-linearity and interactivity) and the appropriation of the terminology to hypertext theory and to hypertext fiction. Chapter 4 and 5 will look at alternative, though related, approaches to electronic fiction: Chapter 4 will examine aspects of collaborative writing in both a print and a digital environment while computer-generated writing stands at the centre of Chapter 5.

A Tablet PC is a portable computing device which combines a regular notebook computer with a digitizing screen that interacts with a complementary electronic pen stylus. The pen allows the user to input data by writing on or by tapping the screen. Like a regular notebook computer, the user can also perform tasks using the mouse and keyboard. A Tablet PC gives the users all the features of a regular notebook computer along with the support to recognize, process, and store electronic/digital ink, enabling a user to make and save hand-written notes or data. In institutions of teaching and learning, instructors often use computer-based materials like web pages, PowerPoint® slides, etc., to explain subject matter. The ability to annotate on presentation information using the electronic stylus of a Tablet PC has attracted the attention of the academic community to use the Tablet PC as a potential tool for increasing the effectiveness of presentations in teaching and learning. Tablet PC-based applications such as OneNote®, WindowsJournal® and Classroom Presenter have been developed to enhance note-taking in classrooms based on the fact that a pen stylus is a more natural form of input device for making notes on the computer as compared to the regular keyboard and mouse. Although tools like OneNote®, WindowsJournal® enhanced the note-taking process on the Tablet PC, they lacked the ability to allow the user to directly annotate on the lecture content. Classroom Presenter provides the ability to integrate classroom notes and the presentation material by allowing the instructors and students to annotate over the lecture material. However, all the above tools lacked the ability to allow a user to take notes over the output window of an arbitrary application like Excel, an active simulator or a movies players output. The Tablet PC based tool, WriteOn, developed at Virginia Tech, addresses this drawback.

WriteOn, when deployed on the Tablet PC in a classroom environment, allows the instructor to utilize electronic ink to annotate on top of any application window visible on the Tablet PC display screen, including those that play active content like a movie or simulation.

WriteOn facilitates a user to annotate over a dynamic application window by activating its virtual transparency surface called the eVellum (electronic vellum). The user can view a movie or an active simulation running in the eVellum background because of its transparent color. The user can deactivate the eVellum to make it invisible by â piercingâ it if he/she wishes to access the desktop or an application window under the vellum window. WriteOn provides the instructor with the ability to broadcast a composite of the dynamic lecture content and ink annotations to the students in real-time. The term dynamic lecture contents is meant to indicate that the content being annotated need not be static words on a background, but may also be window contents that are changing in time. Using WriteOn, the students can make their own notes by writing on the eVellum enabled on top of the lecture stream window without losing visibility of the lecture. The instructor/student can save the ink annotations along with base lecture material as a movie file. The ability of WriteOn to improve classroom presentation and student note-taking as shown by initial tests, were pedagogically very useful. However, in order to deploy WriteOn on large scale in classrooms as an active and effective teaching tool of choice, several aspects of the application had to be improved.

One aspect of the application that needed improvement was the user interface. The primitive Graphical User Interface (GUI) of the WriteOn tool was not easily usable by instructors and students from non-computer science backgrounds. The second aspect needing improvement was the operational performance of the application in terms of its CPU resource utilization. The WriteOn tool has shown to have operational performance issues during the screen capture process. This research therefore aims to address improvements in the GUI to make it more user friendly and increase the operational performance to the point where the user does not notice degradation of a base lecture application. Incorporation of these improvements has led us to rename the application as WriteOn1.0.

WriteOn1.0 implements a picture-based GUI that comprises of two forms: a main form that appears shortly after WriteOn1.0 starts and a toolbar. The WriteOn1.0 toolbar appears in the center of the top edge of the display as soon as the user initiates a task like a screen recording session, by clicking on the appropriate menu button on the main form. The toolbar provides the user, accessibility to perform all the desired activities like annotating, screen recording, presentation broadcast, and piercing of the eVellum by a single-click of the appropriate menu icon. Tool tips that appear when the user points the mouse over a picture icon on the toolbar, explain the task that shall be performed when he/she clicks on the underlying menu icon. WriteOn1.0 introduces a window-like resizable and movable eVellum called the scalable eVellum that it activates in the area of interest specified by the user. Unlike the first implementation of the eVellum which had a fixed location and spanned the entirety of the userâ s desktop window, the instructor/student define the dimensions of the scalable eVellum and can choose to re-dimension, relocate and pierce through it at any point of time during a session. WriteOn1.0 also introduces the transparent mode of operation wherein the instructor/student, without having to deactivate the scalable eVellum can access any underlying window by a right-click of the mouse on the eVellum surface while the ink annotations are intact on the foreground,.

WriteOn1.0 addresses the operational performance issues observed during a screen capture session in WriteOn by capturing the activities only in the area of interest of the user for recording and broadcasting. By combining this scheme with a with a lossless screen capture codec called the MSU screen capture codec that has a high-compression ratio and that is optimized for speed for data compression, WriteOn1.0 greatly improves the operational CPU performance of the tool.

WriteOn1.0 employs various technologies to implement its features. The improvements to operational performance are implemented by using the MSU screen codec from Moscow State Universityâ s Graphics and Media Lab. Microsoft®â s Video for Windows Framework (VfW) and WindowsMedia Player APIâ s are used to realize the module that records the screen activities to an AVI file while DirectShow of DirectX and ConferenceXP APIâ s are used for streaming presentations over a network. WriteOn1.0, with its features like its scalable eVellum, good operational performance and picture-based GUI is aimed at potentially making it a teaching tool of choice across classrooms and changing the method of classroom instruction of courses involving dynamic content.
Master of Science

Thesis advisor: Brian J. Gareau
For my dissertation research, I am focused on the sociopolitical relations of electronics disposal, a less-considered but increasingly important stage in the life cycle of electronics. Although much has already been written on the global trade in hazardous wastes, the Basel Convention that regulates this trade, and the environmental injustice of the global waste trade--with wealthy countries dumping the "negative externalities" of their consumption on vulnerable communities in the global South--the reality today appears to be more complex. Regulators in the Basel Convention and the UN Environment Program, as well as civil society actors in industry and NGOs, have an increased interest in promoting the development of markets and infrastructure in high tech e-waste recycling. Historically, e-wastes have been both talked about, and treated as, a toxic and unwanted byproduct of the digital age. However, today key actors in the regulatory, industrial and civil society spheres are now discussing e-wastes as critical "resources" for economic and technological development. I hypothesize that uncovering the economic, technological and geopolitical drivers of this shift will reveal that the global trade in e-wastes can no longer be described as a clear-cut North/South, "perpetrator-victim," scenario, rather, it must be seen as a dynamic process where environmental inequalities are mitigated and reconstituted in new forms and at various sites. I identify two dominant paradigms that scholars, activists, policy makers and industry actors employ in evaluating the global trade in electronic wastes. I label these two paradigms the "environmental justice evaluation" and the "resource capture evaluation." By engaging concepts from global political economy and environmental sociology (particularly, O'Connor 1979; Harvey 2003; Pellow 2003) and applying them to my case, my dissertation attempts to bring a nuanced perspective to the e-waste debate. My initial findings suggest that both of these frameworks do not account for the key economic processes that are driving the e-waste trade. A better understanding of these processes will better illuminate the pathway to finding meaningful solutions to the persistent, presently illegal global trade in discarded electronics. My data consists of a comprehensive examination of meeting archives from the Basel Convention (where the experts and political decision makers on this issue implement policies that affect the global e-waste trade) spanning from 1992 to the present, as well as reviews of the proceedings of other relevant actors in e-waste policy (for example, annual meetings of the global organization StEP, and publications and pamphlets from trade organizations in the US and abroad and publications from the US government). In addition, I conducted semi-structured interviews with 25 key actors in the national regulatory, global regulatory, industry and NGO spheres in order to understand how the key decision makers in the e-waste trade understand the drivers and implications of the shift "from waste to resources." Finally, I draw on ethnographic observations conducted at a pivotal Basel Convention meeting in 2011, where a decision was made that has the potential to fundamentally reshape the Basel Convention and enable increased global trade in discarded electronics through the development of formalized recycling centers in less-developed countries
Thesis (PhD) — Boston College, 2014
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Sociology

The purpose of this study was to: obtain and review guidelines for designing on a small screen

from several theoretic sources and to purpose own guidelines for this context. There was

chosen for the development of 3 different prototypes meant for the use on 3 different mobile

devices. Those mobile devices had a different screen size and were: an e-reader, PDA and

mobile phone. The prototypes provided the user with a future e-newspaper service (a TV

schedule).

First design principles for good usability on small screens were abstracted from literature.

With this knowledge the three prototypes were developed. The development started with

writing down the functional and user requirements for the prototypes. After that the

developing process had two stages. The first stage was a low-fidelity prototype, this were

sketches of the graphical user interface that was commented by users. The second stage was

a high-fidelity prototype, this stage consisted of three fully functional prototypes. The three

different prototypes were used in a user evaluation. After the evaluation interviews with the

users took place to obtain additional information.

In this research the main question was: “What are the challenges for designing the

(graphical) user interface, as a part of an e-newspaper service which is aimed at use on

multiple devices with heterogeneous screen sizes, to be recognized as the same service?”.

The results from this research are three challenges in designing the (graphical) user interface

for devices with small screens. These challenges are: how to make the user recognize the

service in the software (recognition of service), how to develop one service on multiple

devices (use on multiple devices) and how to develop software that it is useful and pleasant

to use (usable software). In total fifteen guidelines derived from theory were found, this

research shows that thirteen of them are applicable when designing for small screens. Three

of those thirteen are reformulated in this study to make them fit better in the context. Next to

this, seven additional guidelines were proposed in this study. Examples of the purposed

guidelines are: reconstruct the layout from the non-digital service in the interface as much as

possible, explore the targeted user group, built further on their mental model and pay

attention to possible disabilities of the group, implement extra’s that give users a good reason

to use the service and make it easy for the user to select the sought information.

Thesis (M.S.)--State University of New York at Binghamton, Department of Systems Science and Industrial Engineering, Thomas J. Watson School of Engineering and Applied Science, 2008.
Includes bibliographical references.

This essay is a product of our examination work on candidate level in Interaction Design. The aim in this project was to design a digital wallet integrated into a cellular phone and make it as an electronic payment tool. In our project the goal has been to create a digital wallet not just for payment, but also develop it into a complete digital wallet, replacing visa, membership card, student cards, id card and receipt. Our ambition is to take care of current qualities of today's wallet and improve where it is possible so that can be replaceable with the digital wallet.

Linköpings Universitet och Acreo AB i Norrköping bedriver ett forskningssamarbete rörande organisk elektrokemisk elektronik och det man kallar papperselektronik. Målet på Acreo är att kunna trycka denna typ av elektronik med snabba trycktekniker så som offset- eller flexotryck. Idag görs de flesta demonstratorer och prototyper, baserade på denna typ av elektrokemisk elektronik, med manuella och subtraktiva mönstringsmetoder. Det skulle vara intressant att hitta fler verktyg och automatiserade tekniker som kan underlätta detta arbete. Målet med detta examensarbete har varit att utvärdera vilken potential bläckstråleteknik respektive screentryck har som tillverkningsmetoder för organiska elektrokemiska elektroniksystem samt att jämföra de båda teknikernas för- och nackdelar. Vad gäller bläckstråletekniken, så ingick även i uppgiften att modifiera en bläckstråleskrivare avsedd för kontor/hemmabruk för att möjliggöra tryckning av de två grundläggande materialen inom organisk elektrokemisk elektronik - den konjugerade polymeren PEDOT och en elektrolyt.

I denna uppsats rapporteras om hur en procedur för produktion av elektrokemisk elektronik har utvecklats. Världens första elektrokemiska transistor som producerats helt med bläckstråleteknik presenteras tillsammans med fullt fungerande implementeringar i logiska kretsar. Karaktärisering av filmer, komponenter och kretsar som producerats med bläckstråle- och screentrycksteknik har legat till grund för den utvärdering och jämförelse som har gjorts av teknikerna. Resultaten ser lovande ut och kan motivera vidare utveckling av bläckstrålesystem för produktion av prototyper och mindre serier. En kombination av de båda nämnda teknikerna är också ett tänkbart alternativ för småskalig tillverkning.

Linköping University and the research institute Acreo AB in Norrköping are in collaboration conducting research on organic electrochemical electronic devices. Acreo is pushing the development of high-speed reel-to-reel printing of this type of electronics. Today, most demonstrators and prototypes are made using manual, subtractive patterning methods. More tools, simplifying this work, are of interest. The purpose of this thesis work was to evaluate the potential of both inkjet and screen printing as manufacturing tools of electrochemical devices and to conduct a comparative study of these two additive patterning technologies. The work on inkjet printing included the modification of a commercially available desktop inkjet printer in order to print the conjugated polymer PEDOT and an electrolyte solution - these are the two basic components of organic electrochemical devices. For screen printing, existing equipment at Acreo AB was employed for device production.

In this report the successful development of a simple system and procedure for the inkjet printing of organic electrochemical devices is described. The first all-inkjet printed electrochemical transistor (ECT) and fully functional implementations of these ECTs in printed electrochemical logical circuits are presented.

The characterization of inkjet and screen printed devices has, along with an evaluation of how suitable the two printing procedures are for prototype production, been the foundation of the comparison of the two printing technologies.

The results are promising and should encourage further effort to develop a more complete and easily controlled inkjet system for this application. At this stage of development, a combination of the two technologies seems like an efficient approach.

This paper describes the evaluation of screen printed materials fabricated with an additive manufacturing process for flexible biomedical applications. Five different conductive polymeric thick film pastes, printed on a polyimide substrate have been investigated. For the intended biocompatible applications, the cytotoxicity of the used materials was tested through adherent cell test. Furthermore, the electrical resistance, the printed structure thickness, the surface energy and roughness have been examined. Additionally, the mechanical resilience of the printed materials was tested through a bending test. During the bending the electrical resistance of printed meander structures could be monitored indicating failures. Two out of five materials were qualified as non-toxic, all of the materials are useable for flexible electronics, as they provide good electrical and mechanical properties.

Mestrado em Engenharia Física
The increase of organic electronics and consequently, the development of sensors based on organic polymers have attracted a lot of attention of the scientific community. Intrigued by these multifunctional, easily processed and low cost materials, it has started to develop odour biosensors for different applications, including medical field and the detection of various diseases. The present work, is focused in the scaling-up of a devoted laboratory approach, in particular concerning the development of organic odour biosensors (electronic nose concept) based on a conductive polymer (PEDOT:PSS) in a pre-industrial approach and produced by means of electronic printing techniques, such as screen printing and slot die. New carbon microelectrodes with different geometrical parameters were designed and processed by the screen printing technique. Further, the slot die technique was applied in order to print the PEDOT:PSS film over the microelectrodes. After the fabrication process, the sensors were morphologically characterized by optical microscopy, atomic force microscopy, profilometry and electrically identified by the two points probe method. The sensors were tested with the use of different analytes with the main focus on two gynaecological analytes. The resistive and capacitive electrical sensor responses for the analytes were analysed and discussed in depth. Important results were obtained with regard to the influence of the geometrical parameters of the carbon microelectrodes and also to the polymer thickness. Finally, the tests on the sensors were also carried out with the use of other analytes which contained blue cheese.
O desenvolvimento de eletrónica orgânica e consequentemente o desenvolvimento de sensores baseados em polímeros orgânicos, atraíram a atenção da comunidade científica. Motivada pela multifuncionalidade, fácil processamento e baixo custo destes materiais, novos biossensores de odor para diversas aplicações começaram a ser desenvolvidos, incluindo na área médica, para a deteção de doenças. Este trabalho, baseou-se no processo de “scaling-up” de um trabalho prévio que teve um objetivo meramente laboratorial, em particular no desenvolvimento de biossensores orgânicos de odor (conceito de nariz eletrónico), baseados em polímeros orgânicos (PEDOT:PSS) num paradigma pré industrial e fabricados pelo meio de técnicas de impressão de eletrónica orgânica, tais como screen printing e slot die. Foram desenhados novos microelétrodos de carbono com diferentes parâmetros geométricos que foram posteriormente produzidos por screen printing. Através da técnica de impressa de slot die, foram posteriormente impresso filmes de PEDOT:PSS sobre os microelétrodos. Após o processo de fabrico, os sensores foram morfologicamente caraterizados por microscopia ótica, microscopia de força atómica, perfilometria e eletricamente caraterizados através da técnica de duas pontas. Os sensores foram testados para diferentes analitos, nomeadamente para dois analitos ginecológicos. A resposta resistiva e capacitiva dos sensores expostos aos analitos, foi obtida e analisada, com especial atenção na influência dos parâmetros geométricos dos microelétrodos de carbono e também na espessura do polímero. Por fim, os sensores foram também testados para outros analitos compostos por queijo azul.

Practising Shadow Theatre in the West today means to subvert the predominantly negative view of shadow in the Western psyche, to transcend the faintly racist notion of shadow theatre as the quaint practice of traditional people of the East and to contend with the dominant influences of the electronic media on this once powerful and popular art form. This research is through creative practice in the form of the production, Cactus. This performance investigates the use of the screen in contemporary Shadow Theatre and the optimisation of the live theatrical experience. The performance also seeks to integrate mediatized and non-mediatized performance through the combination of live performance and projected images. My research is a social constructivist process to creative practice as research using a pluralistic approach including elements of action research and autobiography. The literature included for review in this study includes work by Brook, Grotowski, Auslander, Sontag, and Schechner. The literature analysis and previous training with Italian company, Teatro Gioco Vita, served to inform the application of my theories as praxis. The central question of this research project is: How can I break the fifth wall (which is the screen) in shadow theatre performance? Subsidiary questions are: How can we harness the advantages of both mediatized and non-mediatized performance to produce a contemporary shadow theatre form catering to the needs of a twenty-first century audience? How can I optimize the live theatrical experience? What is contemporary Shadow Theatre?

This thesis is an investigation of the complex processes and relationships between the physical human performer and the technologically manufactured cyber-human counterpart. I acted as both researcher and the physical human performer, deeply engaged in the moment-to-moment creation of events unfolding within a shared virtual reality environment. As the primary instigator and activator of the cyber-human partner, I maintained a balance between the live and technological performance elements, prioritizing the production of content and meaning. By way of using practice as research, this thesis argues that in considering interactions between cyber-human and human performers, it is crucial to move beyond discussions of technology when considering interactions between cyber-humans and human performers to an analysis of emotional content, the powers of poetic imagery, the trust that is developed through sensory perception and the evocation of complex relationships. A theoretical model is constructed to describe the relationship between a cyber-human and a human performer in the five works created specifically for this thesis, which is not substantially different from that between human performers. Technological exploration allows for the observation and analysis of various relationships, furthering an expanded understanding of ‘movement as content’ beyond the electronic connection. Each of the works created for this research used new and innovative technologies, including virtual reality, multiple interactive systems, six generations of wearable computers, motion capture technology, high-end digital lighting projectors, various projection screens, smart electronically charged fabrics, multiple sensory sensitive devices and intelligent sensory charged alternative performance spaces. They were most often collaboratively created in order to augment all aspects of the performance and create the sense of community found in digital live dance performances/events. These works are identified as one continuous line of energy and discovery, each representing a slight variation on the premise that a working, caring, visceral and poetic content occurs beyond the technological tools. Consequently, a shift in the physical human’s psyche overwhelms the act of performance. Scholarship and reflection on the works have been integral to my creative process throughout. The goals of this thesis, the works created and the resulting methodologies are to investigate performance to heighten the multiple ways we experience and interact with the world. This maximizes connection and results in a highly interactive, improvisational, dynamic, non-linear, immediate, accessible, agential, reciprocal, emotional, visceral and transformative experience without boundaries between the virtual and physical for physical humans, cyborgs and cyber-humans alike.

This dissertation studies rear projection diffusing screens. We provide a methodology, a theoretical background, metrics, and experimental results to aid in the understanding and design of such screens. For this work, a theoretical model has been developed to predict local fluctuations of measured color that appear as image noise in projection screens. This predictive model is based on Fraunhofer diffraction along with Huygens' wavelet analysis and linear systems theory. Of importance are the figures of merit that have been defined and used to compare the theoretical predictions and experimental results. The range of validity of the model has also been determined. We set up an experiment to test the theoretical model. By experimentally varying the numerical aperture of the input illumination, color variations on screens have been measured and characterized. The results of both the experiment and the model show a strong relationship between the polychromatic image noise and the size of the illumination cone. As the size of the illumination cone was decreased from 6 to less than 0.1 millisteradians, there was more than a threefold increase in the figures of merit. Our model shows insight, validates and augments a common rule of thumb. It is often assumed that making the screen structure significantly larger than the coherence length of the source will result in a system with minimal noise. The model shows that this is correct, but it also provides predictions in the cross over region. This allows one to understand how the image noise in a projection system will change as screen designs are changed. Ultimately, this allows screen solutions to be assessed before they are reduced to practice.

Thesis (M.S. in Physics)--Naval Postgraduate School, December 1990.
Thesis Advisor: Maruyama, Xavier K. Second Reader: Buskirk, Fred R. "December 1990." Description based on title screen as viewed on April 1, 2010. DTIC Identifier(s): Transition radiation, beam monitors, charged particle beams, diffuse screens, Optical Transition Radiation, Wartski Interferometers, Cerenkov Radiation, theses. Author(s) subject terms: Transition radiation, Lorentz Factor, diffraction pattern, charged particle beam profiling. Includes bibliographical references (p. 110). Also available in print.

Rapporten behandlar simuleringar, beräkningar och mätningar av HVAC-kablar. En genomgång presenteras av kabelteori samt de olika magnetiska och elektriska effekterna som påverkar skärmströmmarnas storlek.
This report comprises simulations, calculations and measurements of HVAC cables. An introduction to cable theory and a review of the different magnetic and electric effects that has an impact on the amplitude of the screen currents in these cables.

Abstract In this thesis several novel inks based on dry inorganic powders enabling magnetic, piezoelectric and memory resistive (memristive) function were researched for printed electronics applications. Low curing temperature screen–printable magnetic inks for high frequency applications based on dry cobalt nanoparticles were developed in the first part of the work. Three publications were achieved. The first one concentrated on ink formulation and its process development, the second on the utilization of multifunctional surfactant, and the third on the development of the inks for plastic substrates. The magnetic inks developed were cured at 120 °C. The electrical performance, microstructure, surface quality and mechanical durability of printed and cured layers were investigated. Relative permeability values up to 3 and related loss tangents up to 0.01 were achieved at 2 GHz frequency, as well as a pull–off strength of up to 5.2 MPa. The maximum loading level of cobalt nanoparticles was 60 vol–%, after which the stability of the ink started to degrade. The developed ink enabled the miniaturization of a patch antenna. In the second part of the thesis, the formulation of inks based on piezoelectric ceramic particles in powder form with ferroelectric polymers as a matrix material is introduced. The performance and quality of the printed inks and cured layers were investigated. The measured pull off –strength was up to 3.25 MPa, relative permittivity was up to 48 at 1 kHz and piezoelectric constant d31 up to 17 pm/V. The printed piezoelectric layer can be utilized in a pressure sensor. In the third part of the thesis, the development of inks for a novel printed memory component, a memristor, is researched. A synthesis route was developed for an organometallic precursor solution, which was formulated into inkjet–printable form. The printing tests were carried out in order to find the most feasible layer thickness with memristive behaviour. The influence of substrate materials and different thermal treatments on the components’ electrical properties, durability of read/erase –cycles and overall lifetime were also investigated. The prepared memristive patterns remained functional for up to 35 days, while the precursor solution remained usable for over a year. The memristive areas withstood up to 30 read/erase cycles and by utilizing heat treatments the shift in resistance value increased by up to three orders of magnitude
Tiivistelmä Väitöstyössä kehitettiin epäorgaanisten kuivien jauhemaisten materiaalien pohjalta magneettisia, pietsosähköisiä ja memristiivisiä musteita käytettäviksi painettavan elektroniikan sovelluksissa. Työn ensimmäisessä osassa tutkittiin korkean taajuuden sovelluksissa käytettävien magneettisten, matalassa lämpötilassa kovetettavien, jauhemaisiin kobolttinanopartikkeleihin perustuvien silkkipainomusteiden valmistamista. Tulokset on esitetty kolmessa julkaisussa, joista ensimmäinen keskittyi musteen formulointiin, toinen monifunktionaalisen surfaktantin hyödyntämiseen ja kolmas musteen kehittämiseen muovialustalle sopivaksi. Työssä kehitettiin 120 °C:ssa kovettuvia musteita, joista valmistettujen kalvojen suhteellisen permeabiliteetin maksimiarvoksi saatiin 3 ja häviöiden minimiarvoksi 0,01 kahden gigahertsin taajuudella. Pull–off –vetotestin tulokseksi saatiin jopa 5,2 MPa. Musteet säilyivät vakaina enimmillään 60 tilavuusprosentin metallipitoisuudella. Kehitettyä mustetta käytettiin tasoantennin miniatyrisoinnissa. Toisessa osassa kehitettiin pietsosähköisiä musteita, jotka pohjautuivat keraamijauheeseen ja matriisimateriaalina toimivaan ferrosähköiseen muoviin. Niistä valmistettujen kalvojen parhaaksi pull off –vetotestin tulokseksi saatiin 3,25 MPa, permittiivisyyden maksimiarvoksi 48 yhden kilohertsin taajuudella ja d31–pietsovakion maksimiarvoksi jopa 17 pm/V. Kehitettyjä painettuja rakenteita voidaan käyttää painettavissa paineantureissa. Kolmannessa osassa kehitettiin uudentyyppinen painettava muistikomponentti, memristori ja komponenttien valmistamiseksi uusi prekursoriliuoksen synteesi. Syntetisoitu liuos muokattiin mustesuihkutulostettavaksi. Painokokeiden avulla selvitettiin materiaalin paksuus, jolla saatiin aikaan muistivastukselle ominainen memristiivinen käyttäytyminen. Työssä tutkittiin substraattimateriaalien ja mahdollisten lämpökäsittelyjen vaikutusta komponenttien sähköisiin ominaisuuksiin, luku/kirjoitussyklien kestoon sekä käyttöikään. Valmistetut memristiiviset kalvot säilyivät toimivina 35 vuorokautta ja prekursoriliuos yli vuoden. Memristiiviset pinnat kestivät jopa 30 luku/kirjoitussykliä ja vastusarvon muutos saatiin lämpökäsittelyllä kolmea kertaluokkaa suuremmaksi

As the avionics industry is seeking to introduce touch screens into most flight decks, it is vital to understand the interactional challenges and benefits of doing so. The potential benefits and challenges of touch screen technology on flight decks was investigated by means of a variety of qualitative and quantitative research methods (mixed methods approach). A number of research questions are addressed, which have been iteratively developed from the literature, interviews with avionics experts and pilots. This work presents one field study, two lab studies, one observational study, one simulation study and one comparative user study, all investigating various factors/variables that could affect touch screen usability on the flight deck. The first field study investigated interactive displays on the flight deck with search and rescue (SAR) crew members in an operational setting in helicopters. This was the first in-flight experiment where touch screens were evaluated under real conditions. The results showed the impact of target size, device placement and in-flight vibration on targeting accuracy and performance. Presented statistical analyses and observations are essential to understand how to design effective touch screen interfaces for the flight deck. One of the lab studies evaluated (more in depth) the potential impact of display position of touch screens within a simulated cockpit. This was the first experiment that investigated the impact of various display positions on performance following Fitts’ Law experiment. Results revealed that display location has a significant impact on touch screen usability. Qualitative findings from semi-structured interviews and post-experiment questionnaires supported the understanding of interactional issues on a flight deck environment which extended initial design guidelines. Pilots brought attention to the impact of increased G-force (+Gz) as an additional environmental factor that might affect touch screen usability on agile aircrafts. Therefore, a Fitts’ law experiment was conducted to understand the effect of +Gz on touch screen usability. +Gz conditions were simulated with a weight-adjustable wristband, which was the first approach to simulate increased G-force in lab environment. Empirical results and subjective ratings showed a large impact of +Gz on performance and fatigue indices. An observational study focused on Electronic Flight Bag (EFB) (mobile device) usage on the specific domain of Search and Rescue (SAR) helicopters. The novelty in this study was the focus group in which the aim was to find features, content and functionality that a SAR pilot may wish to see in an EFB. From operational observations and interviews with pilot’s operational requirements were defined. A Digital Human Modelling Software was used to define physical constraints of an EFB and develop interface design guidelines. A scenario and virtual prototype was created and presented to pilots. A new way of interaction to manipulate radio frequencies of avionics systems was developed based on findings achieved in this work and other relevant studies. A usability experiment simulating departures and approaches to airports was used to evaluate the interface and compare it with the current system (Flight Management System). In addition, interviews with pilots were conducted to find out their personal impressions and to reveal problem areas of the interface. Analyses of task completion time and error rates showed that the touch interface is significantly faster and less prone to user input errors than the conventional input method (via physical or virtual keypad). Potential problem areas were identified and an improved interface is suggested. Overall, the main contribution of this research is a framework showing the relation between various aspects that could impact the usability of touch screens on the flight deck. Furthermore, design guidelines were developed that should support the usability of interactive displays on the flight deck. This work concludes with a preliminary questionnaire that can help avionic designers to evaluate whether a touch screen is an appropriate user interface for their system.

A general model is developed describing the performance of positive displacement flowmeters. This model allows to predict the performance of any positive displacement meter if 8 coefficients describing the meter design are known. The logic is that a flowmeter performs at a defined pressure loss for a given speed. This pressure loss times flowrate is then energy balanced against all internal loses. Pressure loss and speed are the reasons for leakage. Rotational speed times the theoretical swept volume is the theoretical flowrate and this flowrate, when combined with leakage flow can be used to calculate the effective or true flowrate. The 8 coefficients describe the influence of the design of a meter on laminar leakage flow, turbulent leakage flow, speed related leakage flow, viscous friction, mechanical friction, constant friction, impulse energy losses and ball bearing friction, respectively. This model was applied to a twin-screw type displacement flowmeter which uses two helical rotors which form separate pockets and allow the flow-rate of the fluid to be measured. Based on the general prediction model it was found that for this type of flowmeter mainly two coefficients are the reasons for deviation from linearity. These are the constant friction power losses KC produced by mechanical sliding and the turbulent leakage flow losses Kt ur . When the values of KC and Ktur are zero then the error against flowrate is constant. A complete model of an actual twin-screw type displacement flowmeter was realised, determining all 8 loss coefficients. In order to do so, tests with a twin-screw type displacement flowmeter have been carried out on the overall meter performance, leakage flow losses and bearing friction. The theoretical work includes the determination of all 8 coefficients based on a study of the rotor geometry of the meter and a calculation of the fluid forces and torques acting on the rotors. The theoretical results of the final performance prediction model were compared with experimental results and show a good accordance. It was found that one optimal circumference clearance value can be determined for every different fluid property and flowrate. The flowmeter performance may be increased by minimising mechanical sliding and turbulent leakage flow losses.

A stretchable silver ink was screen printed to TPU sheets, then tensile coupons of the TPU, both bare and laminated to cotton, Denim and spandex fabric, were subjected to 1000 cycles of 20% uniaxial strain. In-situ resistance measurements of printed traces were processed to generate datasets of maximum and minimum resistance per cycle. A mechanistic fit model was used to predict the resistance behavior of the ink across TPU/fabric levels. The results show that traces strained on TPU laminated to spandex (polyester) fibers had an average rate of increase in resistance significantly lower than that of traces strained on bare TPU. The variation in predicted resistance was significantly lower in the spandex group than in the TPU group. Trace width was not found to have a significant effect on the resistance behavior across TPU/fabric groups. More testing is required to understand the effect of lamination to high elasticity fabrics on resistance behavior as it relates to the viscoelastic properties of the fibers and weave structure.

There is a great demand for low-cost disposable sensors in a variety of markets, such as the food chainand health care. No assay is performed more than that of glucose and approximately 85 % of the entirebiosensor market accounts for glucose biosensors. Each year, 6 billion glucose assays are performed andthe majority of them are based on electrochemical detection. Organic electrochemical transistors(OECTs) have favorable properties in terms of low operating voltages and have previously been used asbase for electrochemical detection of glucose. A low-cost disposable biosensor can be achieved by theuse of high throughput printing techniques. Up until now, no printable biosensors based on organic electrochemicaltransistors have been developed. In this thesis a printable miniaturized prototype for a glucose biosensor based on an OECT with a platinizedgate electrode has been designed, developed and evaluated. The biosensor has been functionalizedwith the enzyme glucose oxidase. Different platinum deposition techniques have been used to depositplatinum onto the printed carbon gate electrode: electrodeposition, platinum nanoparticle solutiondeposited either by inkjet printing or pipetting and thermal evaporation. The gate electrodes were characterized with cyclic voltammetry in hydrogen peroxide, ferricyanide andglucose. The characterizations revealed no significant differences between the different deposition techniques.However, with gate electrodes produced by printed carbon followed by electrodeposition ofplatinum it was possible to sense glucose in a concentration in the range of the values for diabetic persons.Thus, the electrodes are a promising option as gate electrodes in a glucose biosensor based on anOECT. The characteristics of the OECT revealed that the responses resembled a transistor.

[ES] RESUMEN La Electrónica Orgánica ha experimentado un gran avance en las últimas décadas, desde que en los años 70 se descubrieran los polímeros conductores. Las características únicas de los semiconductores orgánicos, han permitido el desarrollo de dispositivos electrónicos flexibles y con múltiple funcionalidad, mediante técnicas de fabricación a temperatura ambiente y bajo coste. Uno de los campos en los que estos dispositivos orgánicos han despertado mayor interés es el de su aplicación como sensores. En particular, los sensores basados en los denominados Transistores Orgánicos de película delgada (OTFT's) han experimentado un gran desarrollo debido a sus múltiples ventajas, como simplicidad, elevada sensibilidad, y posibilidad de miniaturización. Existen dos tipos principales de OTFT's: Transistor Orgánico de Efecto de Campo (OFET) y Transistor Electroquímico Orgánico (OECT). Los OECT's constan de tres electrodos (surtidor, drenador y puerta), un semiconductor orgánico (OSC), y un electrolito en contacto con el semiconductor. El funcionamiento de los sensores basados en OECT's se basa en la modulación de la corriente del canal por dopaje o de-dopaje electroquímico desde el electrolito, cuando se aplican tensiones de puerta. Los OECT's resultan especialmente adecuados como sensores químicos debido a su capacidad de operar en medios acuosos. En este trabajo, se han desarrollado OECT's basados en el OSC PEDOT:PSS mediante tecnología Screen-printing. Los transistores se han diseñado variando su geometría, parámetro del que depende la sensibilidad del sensor. Mediante la caracterización eléctrica de los OECT's, se ha podido determinar la geometría óptima en función del analito a detectar. Finalmente, se ha comprobado experimentalmente la validez de estos OECT's como sensores de cationes de diferentes tamaños y de ácido ascórbico, obteniéndose resultados muy satisfactorios. Los OFET's, se han preparado depositando el OSC sobre el dieléctrico y para obtener el canal cuya corriente se modula con la tensión aplicada al electrodo de puerta. En la mayoría de los sensores basados en OFET's, el semiconductor está expuesto al analito. Su funcionamiento se basa en la modificación de la corriente del canal por dopaje o captura de cargas en presencia del analito. En este trabajo, se han desarrollado OFET's basados en TIPS-Pentacene mediante las tecnologías Drop-casting y Spin-coating. Tras establecer la mejor técnica de deposición del semiconductor orgánico se han caracterizado eléctricamente los OFET's. La caracterización eléctrica de estos transistores orgánicos es fundamental para optimizar su uso como sensores químicos. No obstante, las propiedades únicas de los OSC's dificultan la caracterización eléctrica de estos dispositivos con los equipos comerciales actuales, diseñados todos ellos para la caracterización de transistores de Silicio. Para suplir esta necesidad, se ha diseñado un equipo para la caracterización de transistores orgánicos, utilizando componentes comerciales de bajo coste y un software desarrollado específicamente para la determinación de los parámetros característicos de OECT's y OFET's fijados en la norma estándar IEEE 1620-2008.
[CAT] RESUM La Electrònica Orgànica ha experimentat un gran avanç en les últimes dècades, des que en els anys 70 es descobrissin els polímers conductors. Les característiques úniques dels semiconductors orgànics, han permès el desenvolupament de dispositius electrònics flexibles i amb múltiple funcionalitat, mitjançant tècniques de fabricació a temperatura ambient i baix cost. Un dels camps en què aquests dispositius orgànics han despertat més interès és el de la seva aplicació com a sensors. En particular, els sensors basats en els denominats Transistors Orgànics de pel·lícula prima (OTFT s) han experimentat un gran desenvolupament a causa dels seus múltiples avantatges, com simplicitat, elevada sensibilitat, i possibilitat de miniaturització. Hi ha dos tipus principals de OTFT s: Transistor Orgànics d'Efecte de Camp (OFET) i Transistor Electroquímic Orgànic (OECT). Els OECT's consten de tres elèctrodes (sortidor, drenador i porta), un semiconductor orgànic (OSC), i un electròlit en contacte amb el semiconductor. El funcionament dels sensors basats en OECT's es basa en la modulació del corrent del canal per dopatge o de-dopatge electroquímic des del electròlit, quan s'apliquen tensions de porta. Els OECT's resulten especialment adequats com a sensors químics per la seva capacitat d'operar en mitjans aquosos. En aquest treball, s'han desenvolupat OECT's basats en el OSC PEDOT: PSS mitjançant tecnologia Screen-printing. Els transistors s'han dissenyat variant la seua geometria, paràmetre del qual depèn la sensibilitat del sensor. Mitjançant la caracterització elèctrica dels OECT's, s'ha pogut determinar la geometria òptima en funció de l'analit a detectar. Finalment, s'ha comprovat experimentalment la validesa d'aquests OECT's com a sensors de cations de diferents mides i d'àcid ascòrbic, obtenint-se resultats molt satisfactoris. Els OFET's, s'han preparat dipositant el OSC sobre el dielèctric per obtenir el canal i la corrent es modula amb la tensió aplicada a l'elèctrode de porta. En la majoria dels sensors basats en OFET's, el semiconductor està exposat al analit. El seu funcionament es basa en la modificació del corrent del canal per dopatge o captura de càrregues en presència de l'analit. En aquest treball, s'han desenvolupat OFET's basats en TIPS-Pentacene mitjançant les tecnologies "Drop-càsting" i "Spin-coating". Després d'establir la millor tècnica de deposició del semiconductor orgànic s'han caracteritzat elèctricament els OFET's La caracterització elèctrica d'aquests transistors orgànics és fonamental per optimitzar el seu ús com a sensors químics. No obstant això, les propietats úniques dels OSC's dificulten la caracterització elèctrica d'aquests dispositius amb els equips comercials actuals, dissenyats tots ells per a la caracterització de transistors de silici. Per suplir aquesta necessitat, s'ha dissenyat un equip per a la caracterització de transistors orgànics, utilitzant components comercials de baix cost i un programari desenvolupat específicament per a la determinació dels paràmetres característics de OECT's i OFET's fixats en la norma estàndard IEEE 1620-2008.
[EN] ABSTRACT Organic Electronics has been extensively developed along these past decades, since the discovery of conducting polymers in the 1970s. The unique features that these organic semiconductors can offer have allowed the development of many electronic devices with mechanical flexibility and multiple functionalities, using low-temperature and low-cost fabrication technologies. These organic devices have attracted considerable interest for their use in many fields, especially for sensing applications. In particular, Organic Thin-Film Transistors (OTFTs) have paved the way towards the fabrication of efficient sensors due to their many advantages, such as simplicity, high sensitivity, and facile miniaturization. OTFTs can be classified into two types of transistors: Organic Field Effect Transistors (OFET) and Organic Electrochemical Transistors (OECT). The essential components of an OECT are an organic semiconductor film, three electrodes (source, drain and gate), and an electrolyte bridging the semiconductor and the gate electrode. The operation of an OECT-based sensor lies on the modulation of the channel current by electrochemical doping or de-doping from the electrolyte, when gate voltages are applied. OECTs have attracted considerable interest for their application as chemical sensors due to their ability to operate in aqueous environments. In this work, PEDOT: PSS-based OECTs have been prepared by Screen-printing. The effect of the geometry on the sensor sensitivity has been investigated by comparing OECTs with different channel and gate areas ratio. The electrical characteristics of the OECTs have been used to determine the geometry that optimizes their performance for sensing different analytes. Finally, the use of these OECTs for the detection of cations and ascorbic acid has been experimentally assessed, with satisfactory and promising results. The OFET's have been prepared by depositing the organic semiconductor on the dielectric and thus obtain the chanel whose current is modulated by the voltage applied to the gate electrode. In most of the OFET-based sensors, the semiconductor is exposed to the analyte. Their operation is based on the modification of the channel current by charge doping or trapping due to the analyte. In this work, OFETs based on TIPS-pentacene have been prepared by Drop-casting and Spin-coating. The best technique for deposition of this organic semiconductor has been initially identified. Then, the electrical characteristics of these OFETs have been determined. The electrical characterization of these organic transistors is essential for their optimization as chemical sensors. However, the unique properties of organic semiconductors render difficult the electrical characterization of these transistors with current commercial devices, since these have been all designed for characterizing Si-based transistors. A device which allows for systematic characterization of organic transistors has been designed therefore, using low-cost commercial components and a software that has been specifically developed for the determination of the reporting parameters for OFETs and OECTs, as specified in the IEEE 1620-2008 standard.
El trabajo desarrollado en los artículos ha sido posible gracias a los distintos proyectos de investigación de financiación pública dentro del marco de proyectos del Ministerio de Educación y Ciencia del Gobierno de España/Fondos FEDER (grant number MAT2015-64139-C4-3-R (MINECO/FEDER)) y Fondos de la Generalitat Valenciana (grant number AICO/2015/103).
Pérez Fuster, C. (2019). Diseño y caracterización de sensores para la medida de parámetros químicos y biológicos mediante Organic Thin-film transistors [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/118793
TESIS

Electricity is the fastest-growing type of end-use energy consumption in the world, and its generation and usage trends are changing. Hence, the power electronics that control the flow and conversion of electrical energy are an important research area. Advanced power electronics with improved efficiency, power density, reliability, and functionality are critical in data center, transportation, motor drive, renewable energy, and grid applications, among others. Wide-bandgap power semiconductors are enabling power electronics to meet these growing demands, and have thus begun appearing in commercial products, such as traction and solar inverters. Looking ahead, even greater strides can be made in medium-voltage systems due to the development of silicon carbide power devices with voltage ratings exceeding 10 kV. The ability of these devices to switch higher voltages faster and with lower losses than existing semiconductor technologies will drastically reduce the size, weight, and complexity of medium-voltage systems. However, these devices also bring new challenges for designers. This dissertation will present a package for 10 kV silicon carbide power MOSFETs that addresses the enhanced electric fields, greater electromagnetic interference, worsened dynamic imbalance, and higher heat flux issues associated with the packaging of these unique devices. Specifically, due to the low and balanced parasitic inductances, the power module prototype is able to switch at record speeds of tens of nanoseconds with negligible ringing and voltage overshoot. An integrated common-mode current screen contains the current that is generated by these fast voltage transients within the power module, rather than flowing to the system ground. This screen connection simultaneously increases the partial discharge inception voltage by reducing the electric field strength at the triple point of the insulating ceramic substrate. Further, field-grading plates are used in the bus bar to reduce the electric field strength at the module terminations. The heat flux is addressed by employing direct-substrate, jet-impingement cooling. The cooler is integrated into the module housing for increased power density.
Ph. D.
Electricity is the fastest-growing type of end-use energy consumption in the world, and its generation and usage trends are changing. Hence, the power electronics that control the flow and conversion of electrical energy are an important research area. Advanced power electronics with improved efficiency, power density, reliability, and functionality are critical in data center, transportation, motor drive, renewable energy, and grid applications, among others. Wide-bandgap power semiconductors are enabling power electronics to meet these growing demands, and have thus begun appearing in commercial products, such as traction and solar inverters. Looking ahead, even greater strides can be made in medium-voltage systems due to the development of silicon carbide power devices with voltage ratings exceeding 10 kV. The ability of these devices to switch higher voltages faster and with lower losses than existing semiconductor technologies will drastically reduce the size, weight, and complexity of medium-voltage systems. However, these devices also bring new challenges for designers. This dissertation will present a package for 10 kV silicon carbide power MOSFETs that addresses the enhanced electric fields, greater electromagnetic interference, worsened dynamic imbalance, and higher heat flux issues associated with the packaging of these unique devices. Specifically, due to the low and balanced parasitic inductances, the power module prototype is able to switch at record speeds of tens of nanoseconds with negligible ringing and voltage overshoot. An integrated common-mode current screen contains the current that is generated by these fast voltage transients within the power module, rather than flowing to the system ground. This screen connection simultaneously increases the partial discharge inception voltage by reducing the electric field strength at the triple point of the insulating ceramic substrate. Further, field-grading plates are used in the bus bar to reduce the electric field strength at the module terminations. The heat flux is addressed by employing direct-substrate, jet-impingement cooling. The cooler is integrated into the module housing for increased power density.

Orientador: Giovani Fornereto Gozzi
Resumo: Dispositivos Eletroluminescentes (EL) são comumente utilizados para iluminação ambiente e transmissão visual de informações, possuem uma enorme gama de aplicações em setores diversos, como para tratamento fototerápico e decoração. Entre as atuais tecnologias, os dispositivos produzidos com compósitos eletroluminescentes têm potencial de emprego em aplicações emergentes devido ao seu baixo custo, flexibilidade mecânica e escalabilidade. Estas vantagens tecnológicas estão atreladas ao fato destes dispositivos poderem ser produzidos utilizando-se técnicas de impressão gráfica, como por exemplo, a técnica de impressão serigráfica. Neste sentido, este trabalho tem como objetivo o desenvolvimento de dispositivos EL totalmente impressos utilizando a técnica de impressão serigráfica. Para tanto, a pasta condutora transparente (PCT) e a pasta de prata (PTF), ambas fornecidas pela empresa TICON, foram utilizadas para a produção de eletrodos transparentes e opacos, respectivamente. A camada ativa dos dispositivos foi produzida com o compósito eletroluminescente (PEL), o qual foi desenvolvido durante o presente estudo. Filmes dos materiais PCT, PEL e PTF foram depositados utilizando-se telas com diversas lineaturas e caracterizados com relação às suas propriedades morfológicas, elétricas e ópticas, com a finalidade de identificar as melhores lineaturas de telas serigráficas para o processamento de cada um dos materiais. Por fim, dispositivos EL do tipo LECEL (Light-Emitting Composite Ele... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Electroluminescent (EL) devices have a wide range of applications. Among current technologies, devices produced with electroluminescent composites have potential for use in emerging applications due to their low cost, flexibility and scalability. Scalability and cost-effectiveness are characteristics also related to device processing methods, amongst which printing techniques, such as screen-printing, are the most appropriated to achieve these goals. Therefore, this research regards on development of screen-printed EL devices. For this purpose, the transparent conductive paste (PCT) and the silver paste (PTF), both sourced by TICON, were used for transparent and opaque electrodes fabrication, respectively. The active layer of the devices have been produced with an electroluminescent composite (PEL) developed during the present study. We have produced screen-printed films with the PCT, PEL and PTF materials using screens with different mesh counts to study the influence of mesh count on the morphological, electrical and optical properties of the films. In addition, we have performed a study regarding the influence of mesh count on the EL device performance parameters. As main result, we have fabricated a screen-printed EL device, using screens with appropriated mesh counts for deposition of each material, which exhibited luminance of 50 cd/m2 (at 110 V) and turn-on voltage of (18 ± 2) V.
Mestre

Organic electronic biosensors are developed as suitable devices that can transform electrochemical processes within the cell membrane into an electronic signal and enable to measure electrical activity of excitable cells and tissues both in vitro and in vivo and thus represent valuable alternative to current cell monitoring methods. In this work we focus on the fabrication of electrophysiological sensors based on organic semiconductors printed by the material printing method. Microelectrode arrays (MEAs) are active components of the device, which can monitore cellular activity and above that stimulating cells with electrical pulses. The proposed platform should be used for cytotoxicity of potential drugs especially on cardiac cells (cardiomyocytes). The experimental part focus on specific production processes of platforms, which were prepared in the laboraty with emphasis on biocompatibility and conductivity of device.

Bioresorbable implants are an attractive alternative to metallic bone fixation devices and offer potential to eliminate some of the clinical challenges with the latter. This work explores the manufacturing of fully bioresorbable fibre-reinforced composite rods and screws for such applications. Poly lactic acid (PLA) and phosphate glass fibres (PGF) were combined to provide mechanical reinforcement and biocompatibility characteristics. Aligned and randomly reinforced PLA/PGF composites were prepared by compression moulding prior to thermomechanical deformation into rod and screw forms. In vitro degradation and mechanical properties retention were investigated in phosphate buffered saline (PBS) at 37°C. The composite rods and screws exceeded published data for bioresorbable implants in their virgin state and were towards the upper range of cortical bone properties. The properties reduced rapidly in an aqueous medium and this was attributed to matrix plasticisation and fibre/matrix disbonding. The degraded samples maintained strength and stiffness close to the lower limits of the cortical bone. Water uptake and mass loss for composites exceeded equivalent values for PLA alone due to water wicking at the fibre/matrix interface. Ion release tests correlated linearly with mass loss profiles confirming that the dominant degradation mechanism was fibre dissolution. The PLA/PGF composites also exhibited good biocompatibility to human osteosarcoma and human mesenchymal stem cells.

The first part of the thesis deals with electron microscopy and physical model fluid flow. In the next part, a three-dimensional model is created in programme SolidWorks. It is the model of scintilating detector with aperture or screen with three hundred little apertures. These models are submitted to analysis focusing on investigation of the gas flow at different pressure in chamber of specimen ESEM using Cosmos FloWorks system. The results of the analysis of both apertures variants are compared with the request to minimize the pressure in the trajectory of the secondary electrons as well as in the chamber of specimen.