1,485 research outputs found

    Towards Practical Triboelectric Nanogenerator for Mechanical Energy Harvesting and Self-powered Sensing

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    Triboelectric nanogenerator (TENG) offers a promising solution as a decentralised energy source to sustainably power the ever-growing mobile electronics. TENG’s characteristics such as high output, versatile working modes and broad material availability have made it viable but still there are a few issues that limit practical applications of TENG. This thesis aims to tackle some of the practical limitations of TENGs to be used as wearable energy harvesters or self-powered sensors. Firstly, to address the poor stretchability of TENG with rigid metal / carbon electrodes for wearable applications, a soft and highly stretchable solid polymer electrode (SPE) based on biocompatible PVA infused with ionically conductive ingredient was developed as the TENG electrode. The use of SPE endows the TENG with high stretchability, superb transparency, environmental stability, and enhanced electrical output. Then the requirement of complex power management system of conventional TENG with AC output was simplified with a new design of DC-TENG boosted by a dual-breakdown mechanism. The DC output could be directly utilized by small electronics without the need of rectifiers, thus reducing complexity and energy loss. Lastly, for TENG-based sensors, to overcome the errors caused by TENG output variations under changing environment, a new method of extracting sensing signals independent of intrinsic TENG output variations is proposed. This research has yielded several important scientific contributions in the device design, optimisation and application of TENG. These findings provide new opportunities to improve TENGs in terms of wearing comfort, system complexity and sensing reliability, thus greatly enhancing the practical application of TENGs in real-life scenarios

    2017 GREAT Day Program

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    SUNY Geneseo’s Eleventh Annual GREAT Day.https://knightscholar.geneseo.edu/program-2007/1011/thumbnail.jp

    An investigation of entorhinal spatial representations in self-localisation behaviours

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    Spatial-modulated cells of the medial entorhinal cortex (MEC) and neighbouring cortices are thought to provide the neural substrate for self-localisation behaviours. These cells include grid cells of the MEC which are thought to compute path integration operations to update self-location estimates. In order to read this grid code, downstream cells are thought to reconstruct a positional estimate as a simple rate-coded representation of space. Here, I show the coding scheme of grid cell and putative readout cells recorded from mice performing a virtual reality (VR) linear location task which engaged mice in both beaconing and path integration behaviours. I found grid cells can encode two unique coding schemes on the linear track, namely a position code which reflects periodic grid fields anchored to salient features of the track and a distance code which reflects periodic grid fields without this anchoring. Grid cells were found to switch between these coding schemes within sessions. When grid cells were encoding position, mice performed better at trials that required path integration but not on trials that required beaconing. This result provides the first mechanistic evidence linking grid cell activity to path integration-dependent behaviour. Putative readout cells were found in the form of ramp cells which fire proportionally as a function of location in defined regions of the linear track. This ramping activity was found to be primarily explained by track position rather than other kinematic variables like speed and acceleration. These representations were found to be maintained across both trial types and outcomes indicating they likely result from recall of the track structure. Together, these results support the functional importance of grid and ramp cells for self-localisation behaviours. Future investigations will look into the coherence between these two neural populations, which may together form a complete neural system for coding and decoding self-location in the brain

    Blending the Material and Digital World for Hybrid Interfaces

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    The development of digital technologies in the 21st century is progressing continuously and new device classes such as tablets, smartphones or smartwatches are finding their way into our everyday lives. However, this development also poses problems, as these prevailing touch and gestural interfaces often lack tangibility, take little account of haptic qualities and therefore require full attention from their users. Compared to traditional tools and analog interfaces, the human skills to experience and manipulate material in its natural environment and context remain unexploited. To combine the best of both, a key question is how it is possible to blend the material world and digital world to design and realize novel hybrid interfaces in a meaningful way. Research on Tangible User Interfaces (TUIs) investigates the coupling between physical objects and virtual data. In contrast, hybrid interfaces, which specifically aim to digitally enrich analog artifacts of everyday work, have not yet been sufficiently researched and systematically discussed. Therefore, this doctoral thesis rethinks how user interfaces can provide useful digital functionality while maintaining their physical properties and familiar patterns of use in the real world. However, the development of such hybrid interfaces raises overarching research questions about the design: Which kind of physical interfaces are worth exploring? What type of digital enhancement will improve existing interfaces? How can hybrid interfaces retain their physical properties while enabling new digital functions? What are suitable methods to explore different design? And how to support technology-enthusiast users in prototyping? For a systematic investigation, the thesis builds on a design-oriented, exploratory and iterative development process using digital fabrication methods and novel materials. As a main contribution, four specific research projects are presented that apply and discuss different visual and interactive augmentation principles along real-world applications. The applications range from digitally-enhanced paper, interactive cords over visual watch strap extensions to novel prototyping tools for smart garments. While almost all of them integrate visual feedback and haptic input, none of them are built on rigid, rectangular pixel screens or use standard input modalities, as they all aim to reveal new design approaches. The dissertation shows how valuable it can be to rethink familiar, analog applications while thoughtfully extending them digitally. Finally, this thesis’ extensive work of engineering versatile research platforms is accompanied by overarching conceptual work, user evaluations and technical experiments, as well as literature reviews.Die Durchdringung digitaler Technologien im 21. Jahrhundert schreitet stetig voran und neue Geräteklassen wie Tablets, Smartphones oder Smartwatches erobern unseren Alltag. Diese Entwicklung birgt aber auch Probleme, denn die vorherrschenden berührungsempfindlichen Oberflächen berücksichtigen kaum haptische Qualitäten und erfordern daher die volle Aufmerksamkeit ihrer Nutzer:innen. Im Vergleich zu traditionellen Werkzeugen und analogen Schnittstellen bleiben die menschlichen Fähigkeiten ungenutzt, die Umwelt mit allen Sinnen zu begreifen und wahrzunehmen. Um das Beste aus beiden Welten zu vereinen, stellt sich daher die Frage, wie neuartige hybride Schnittstellen sinnvoll gestaltet und realisiert werden können, um die materielle und die digitale Welt zu verschmelzen. In der Forschung zu Tangible User Interfaces (TUIs) wird die Verbindung zwischen physischen Objekten und virtuellen Daten untersucht. Noch nicht ausreichend erforscht wurden hingegen hybride Schnittstellen, die speziell darauf abzielen, physische Gegenstände des Alltags digital zu erweitern und anhand geeigneter Designparameter und Entwurfsräume systematisch zu untersuchen. In dieser Dissertation wird daher untersucht, wie Materialität und Digitalität nahtlos ineinander übergehen können. Es soll erforscht werden, wie künftige Benutzungsschnittstellen nützliche digitale Funktionen bereitstellen können, ohne ihre physischen Eigenschaften und vertrauten Nutzungsmuster in der realen Welt zu verlieren. Die Entwicklung solcher hybriden Ansätze wirft jedoch übergreifende Forschungsfragen zum Design auf: Welche Arten von physischen Schnittstellen sind es wert, betrachtet zu werden? Welche Art von digitaler Erweiterung verbessert das Bestehende? Wie können hybride Konzepte ihre physischen Eigenschaften beibehalten und gleichzeitig neue digitale Funktionen ermöglichen? Was sind geeignete Methoden, um verschiedene Designs zu erforschen? Wie kann man Technologiebegeisterte bei der Erstellung von Prototypen unterstützen? Für eine systematische Untersuchung stützt sich die Arbeit auf einen designorientierten, explorativen und iterativen Entwicklungsprozess unter Verwendung digitaler Fabrikationsmethoden und neuartiger Materialien. Im Hauptteil werden vier Forschungsprojekte vorgestellt, die verschiedene visuelle und interaktive Prinzipien entlang realer Anwendungen diskutieren. Die Szenarien reichen von digital angereichertem Papier, interaktiven Kordeln über visuelle Erweiterungen von Uhrarmbändern bis hin zu neuartigen Prototyping-Tools für intelligente Kleidungsstücke. Um neue Designansätze aufzuzeigen, integrieren nahezu alle visuelles Feedback und haptische Eingaben, um Alternativen zu Standard-Eingabemodalitäten auf starren Pixelbildschirmen zu schaffen. Die Dissertation hat gezeigt, wie wertvoll es sein kann, bekannte, analoge Anwendungen zu überdenken und sie dabei gleichzeitig mit Bedacht digital zu erweitern. Dabei umfasst die vorliegende Arbeit sowohl realisierte technische Forschungsplattformen als auch übergreifende konzeptionelle Arbeiten, Nutzerstudien und technische Experimente sowie die Analyse existierender Forschungsarbeiten

    Frontiers of Humanity and Beyond: Towards new critical understandings of borders. Working Papers

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    UIDB/04666/2020 UIDP/04666/2020publishersversionpublishe

    Novel polymeric and oligomeric materials for organic electronic devices

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    Die enormen Fortschritte im Bereich der organischen Elektronik in den letzten Jahrzehnten haben zur Entwicklung effizienter optoelektronischer Bauelemente geführt wie z. B. organische Leuchtdioden (OLEDs), organische Feldeffekttransistoren (OFETs) und organische Photovoltaikzellen (OPV). Darüber hinaus ermöglichen halbleitende Polymere die Herstellung kostengünstiger, großflächiger elektronischer Bauelemente mit Hilfe von Niedertemperatur Lösungsverfahren auf flexiblen Substraten. Der erste Teil dieser Arbeit befasste sich mit der Entwicklung von Host-Materialien für die emittierende Schicht (EML) von OLEDs. Effiziente Host-Materialien sollten bestimmte Eigenschaften aufweisen, z. B. eine hohe Triplett-Energie, einen hohen und ausgeglichenen Ladungsträgertransport, geeignete Grenzorbitalniveaus, die mit denen der Nachbarschichten übereinstimmen, und morphologische Stabilität. Zu diesem Zweck wurden Polymere auf Carbazolbasis mit einer elektronenziehenden Gruppe (EWG) an verschiedenen Stellen der Kette entworfen und durch Suzuki Kupplung synthetisiert. Die Polymere wurden chemisch und optisch charakterisiert, bevor sie nach Dotierung mit Tris(2-phenylpyridin)iridium(III) (Ir(ppy)3) in eine funktionierende grüne OLED eingebaut wurden. Zusätzlich wurden die Ladungstransporteigenschaften durch die Herstellung von Einzelträgergeräte untersucht. Der zweite Teil widmete sich der Herstellung von Halbleitermaterialien für OFET Anwendungen. Nach einem neuartigen Moleküldesign wurde eine Reihe von Verbindungen auf der Basis von Diketopyrrolopyrrol (DPP) und Thiophen durch Stille-Kupplung und phosphinfreie direkte Heteroarylierung synthetisiert. Dieses molekulare Design erwies sich als flexibel für die Synthese neuartiger Derivate durch Modifikation der Endgruppen. Die Korrelation zwischen Struktur und Morphologie wurde ebenfalls untersucht. Die Mobilität der Ladungsträger, welche von der chemischen Struktur und Morphologie des Halbleiters beeinflusst wird, ist einer der wichtigsten Parameter eines OFET. Daher wurden die erhaltenen Materialien mit niedriger Bandlücke in Transistoren verschiedener Architekturen integriert, die durch Lösungsverfahren wie Spin-Coating und Scherbeschichtung hergestellt wurden. Die Mobilität sowie andere OFET-Parameter wurden im p- und n-Typ-Betrieb gemessen.:1 Theoretical background 1.1 Introduction 1.2 Organic semiconductors 1.3 Organic Light Emitting Diodes 1.3.1 Physics of OLEDs 1.3.2 Solution processable OLEDs 1.3.3 Polymer Light-Emitting Diodes 1.4 Organic Field-Effect Transistors 1.4.1 Device operation 1.4.2 Ambipolar transistors 1.5 Synthesis of π-conjugated polymers 1.6 Characterisation methods 1.6.1 Chemical structure characterisation 1.6.2 Optical characterisation 1.6.3 Morphology and microstructure 2 Motivation and aim 3 Results and discussion 3.1 Polymers for ambipolar semiconductors 3.1.1 Molecular design 3.1.2 (N-carbazole)triphenylphosphine oxide polymers 3.1.3 Bis(carbazol-3-yl)triphenylphosphine oxide polymers 3.1.4 ((Carbazol-3-yl)phenoxy)hexyl diphenylphosphinate polymers 3.1.5 ((Phenothiazin-10-yl)phenyl)diphenylphosphine oxide polymers 3.1.6 Device integration 3.1.7 Summary 3.2 DPP based molecules for OFETs 3.2.1 Molecular design 3.2.2 DBT-I series 3.2.3 DBT-II 3.2.4 Device integration 3.2.5 Summary 4 Conclusions and outlook 5 Experimental part 6 Supporting Information 7 BibliographyStaggering progress in the field of organic electronics over the past decades has led to the development of efficient optoelectronic devices, such as organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs)and organic photovoltaic cells (OPV). Moreover, semiconducting polymers enable the fabrication of low-cost, large-area electronic devices using low-temperature solution-processing methodologies on flexible substrates. The first part of this thesis focused on the development of host materials for the emitting layer (EML) of an OLED. Efficient hosts should possess a number of properties, such as high triplet energy, good and balanced charge-carrier transport, suitable frontier orbital levels that match those of the neighbouring layers, and morphological stability. To this end, carbazole-based polymers featuring an electron-withdrawing group (EWG) at different positions of the chain were designed and synthesised by Suzuki coupling. Chemical and optical characterisations of the polymers were performed prior to their incorporation into a functioning green OLED upon doping with tris(2-phenylpyridine)iridium(III) (Ir(ppy)3). Additionally, the charge-transport properties were studied through the fabrication of single-carrier devices. The second part was dedicated to the production of semiconductor materials for OFET applications. Following a novel molecular design, a series of compounds based on diketopyrrolopyrrole (DPP) and thiophene were synthesised by Stille coupling and phosphine-free direct heteroarylation. This molecular design was proven to be flexible for the synthesis of novel derivatives by modification of the end-groups. The correlation between structure and morphology was also studied. Mobility, influenced by the chemical structure and morphology of the semiconductor, is one of the most important parameters of an OFET. Thus, the obtained low bandgap materials were integrated into devices of different architectures, fabricated by solution processing methodologies, such as spin coating and shear coating, and the mobility, as well as other OFET parameters, were measured in p- and n-type operation.:1 Theoretical background 1.1 Introduction 1.2 Organic semiconductors 1.3 Organic Light Emitting Diodes 1.3.1 Physics of OLEDs 1.3.2 Solution processable OLEDs 1.3.3 Polymer Light-Emitting Diodes 1.4 Organic Field-Effect Transistors 1.4.1 Device operation 1.4.2 Ambipolar transistors 1.5 Synthesis of π-conjugated polymers 1.6 Characterisation methods 1.6.1 Chemical structure characterisation 1.6.2 Optical characterisation 1.6.3 Morphology and microstructure 2 Motivation and aim 3 Results and discussion 3.1 Polymers for ambipolar semiconductors 3.1.1 Molecular design 3.1.2 (N-carbazole)triphenylphosphine oxide polymers 3.1.3 Bis(carbazol-3-yl)triphenylphosphine oxide polymers 3.1.4 ((Carbazol-3-yl)phenoxy)hexyl diphenylphosphinate polymers 3.1.5 ((Phenothiazin-10-yl)phenyl)diphenylphosphine oxide polymers 3.1.6 Device integration 3.1.7 Summary 3.2 DPP based molecules for OFETs 3.2.1 Molecular design 3.2.2 DBT-I series 3.2.3 DBT-II 3.2.4 Device integration 3.2.5 Summary 4 Conclusions and outlook 5 Experimental part 6 Supporting Information 7 Bibliograph

    A War of Words: The Forms and Functions of Voice-Over in the American World War II Film — An Interdisciplinary Analysis

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    Aside from being American World War II films, what else do the following films have in common? The Big Red One; Hacksaw Ridge; Harts War; Mister Roberts; Stalag 17; and The Thin Red Line — all have voice-over in them. These, and hundreds of other war films have voice-overs that are sometimes the thoughts of a fearful soldier; the wry observations of a participant-observer; or the declarations of all-knowing authoritative figures. There are voice-overs blasted out through a ships PA system; as the reading of a heart-breaking letter; or as the words of a dead comrade, heard again in the mind of a haunted soldier. This thesis questions why is voice-over such a recurring phenomenon in these films? Why is it conveyed in so many different forms? What are the terms for those different forms? What are their narrative functions? A core component of this thesis is a new taxonomy of the six distinct forms of voice-over: acousmatic, audioemic, epistolary, objective, omniscient, and subjective. However, the project is more than a structuralist taxonomy that merely serves to identify, and define those forms. It is also a close examination of their narrative functions beyond the unimaginative trope that voice-over in war films is simply a convenient storytelling device. Through interdisciplinarity — combined with a realist framework — I probe the correlations between: the conditions, codification, and suppression of speech within the U.S. military, and the manifestations of that experience through the cinematic device, and genre convention of voice-over. In addition, I present a radically new interpretation of the voice-overs in The Thin Red Line (Terrence Malick, 1998) as being both a choric meta-memorial to James Jones; and a Greek tragedy — with its replication of the stagecraft of Aeschylus, in its use of the cosmic frame, and the inclusion of a collective character, which I have named ‘The Chorus of Unknown Soldiers’. The overall result is a more logical, and nuanced explanation of the forms, functions, and prevalent use of voice-over in the American World War II film

    The Significance of Things: A Theological Account of Sorrow Over Anthropogenic Loss

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    This thesis proposes that sorrow over anthropogenic loss can bear moral authority in both its experience and expression, and further that this sorrow is most fittingly expressed as prayer. I introduce a metaphysical account of sorrow as a morally charged condition which constitutes a critical correction to contemporary accounts of emotion. I apply this account to anthropogenic loss via a theological anthropology which presents humans as priests of creation. There are two motivations for this thesis: correcting a theological gap in treatments of feeling about anthropogenic loss and offering a constructive moral theological anthropology. These motivations are related. Anthropogenic loss is a particular context which nevertheless reveals fundamental truth about the vocation of the human. Against the context of psycho-social research into ‘feeling’ prompted by climate change and ecological collapse, I investigate the definitional challenge presented by ‘emotions’ in this literature. I introduce the passion of sorrow via Augustine, Thomas Aquinas, late medieval readings of Christ’s passion, and the Black theological tradition. These distinct traditions share an appreciation of sorrow in Christian moral formation, particularly when expressed as prayer. I then apply this account of sorrow to anthropogenic loss. In dialogue with Bruno Latour, I address the culturally conditioned nature of human feeling about the loss of non-human creatures, proposing that this is not a barrier to its moral role because creation consists of sign-making and sign-receiving agents. Our cultural creaturely identity does, however, require a governing narrative in which to interpret these signs and guide our response; the theological anthropologies of Maximus the Confessor and Jean-Louis Chrétien frame humans as priests of creation. Finally, I look to sign-making and sign-reception beyond the Church. Hannah Arendt’s description of world-making as communicative action guides my claim that prayerful sorrow over anthropogenic loss is politically efficacious, and therefore belongs in public

    Microfluidic systems based on electroactive polymers technology

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    Dielectric elastomer actuators (DEAs) have been widely investigated for more than 30 years. Lately, several fabrication methods have successfully allowed the creation of very thin elastomer and electrode layers. The development of attractive applications, in which DEAs offer advantages over conventional technologies, is thus necessary for the advance of the technology. In this work, new biocompatible microfluidic devices based on DEAs are developed. In the first part of this thesis, several prototypes of peristaltic pumps of single layer dielectric elastomer actuators are designed, manufactured and characterized. Although these prototypes were not able to produce fluid flow, novel insights into the capabilities of Electroactive Polymer technology were gained. In the second part of this work, a pumping micromixer as a novel application of dielectric elastomer stacked actuators is manufactured. The pumping micromixer is based on peristaltic movements, which gently act as a mixer and a pump for microfluidics. Experimental data show a maximal flow rate of 21.5 µL/min at 10 Hz. Image analysis at the outlet proves a 50/50 mixing when all actuators are functioning at the same pace and voltage. The performance of the pumping micromixer is further studied with the Finite Element Method, using the COMSOL Multiphysics® software. Simulations demonstrate the versatility of the pumping characteristics of such a microdevice, from very few µL/min to mL/min, and from a very low pressure in the range of Pa to hundreds of kPa, by only changing the duty cycle, phase shift and actuation frequency

    Advanced Materials and Technologies in Nanogenerators

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    This reprint discusses the various applications, new materials, and evolution in the field of nanogenerators. This lays the foundation for the popularization of their broad applications in energy science, environmental protection, wearable electronics, self-powered sensors, medical science, robotics, and artificial intelligence
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