Sensitive and Makeable Computational Materials for the Creation of Smart Everyday Objects

The vision of computational materials is to create smart everyday objects using the materi- als that have sensing and computational capabilities embedded into them. However, today’s development of computational materials is limited because its interfaces (i.e. sensors) are unable to support wide ranges of human interactions , and withstand the fabrication meth- ods of everyday objects (e.g. cutting and assembling). These barriers hinder citizens from creating smart every day objects using computational materials on a large scale. To overcome the barriers, this dissertation presents the approaches to develop compu- tational materials to be 1) sensitive to a wide variety of user interactions, including explicit interactions (e.g. user inputs) and implicit interactions (e.g. user contexts), and 2) makeable against a wide range of fabrication operations, such cutting and assembling. I exemplify the approaches through five research projects on two common materials, textile and wood. For each project, I explore how a material interface can be made to sense user inputs or activities, and how it can be optimized to balance sensitivity and fabrication complexity. I discuss the sensing algorithms and machine learning model to interpret the sensor data as high-level abstraction and interaction. I show the practical applications of developed computational materials. I demonstrate the evaluation study to validate their performance and robustness. In the end of this dissertation, I summarize the contributions of my thesis and discuss future directions for the vision of computational materials

RECYCLING OF WASTEPAPER INTO FUNCTIONALIZED ELECTRONIC PAPER

One of the main objectives of this work has in view a concern of our society: Sustainability. With the degradation of the planet's well-being and environmental quality, and being an in-creasingly irreversible process in recent years, it only makes sense to focus all our attention on improving sustainability and reducing electronic waste, following the vision of UN Sustainable Goals and the European Green Deal. This work is committed to the fabrication of multi-functional electronic paper (e-paper) through recycling the waste in a low-cost method, targeted to reduce the use of critical raw materials. Furthermore, the e-paper has been designed for multi-purpose smart applications such as mech-ano-responsive energy harvesters, interactive pressure sensors, or energy storage systems. This work is based on studies previously carried out at CENIMAT and CEMOP. However, this work aims at a more ecological approach, as it uses cellulose obtained from used newspapers that would have no other destination than recycling. All recycled samples and fabricated electronic devices were investigated by using chemical, electrical, and morphological characterization techniques. The successful functionalization of recycled paper (RP) showed good performance as an e-paper. The e-paper has been designed for a mechano-responsive energy harvesting device, that gener-ates current under charge transfer mechanism at PANI-Cellulose/electrode Interface layer. The manufactured devices present satisfactory results (output voltage: 17 - 20 V, output current: 0.85 - 1.6 μA, power density: 0.16 - 0.35 Wm-2) in the production of energy through mechanical impulses, managing to light up several LEDs in series. Moreover, the E-paper has been investigated as a flexible paper-based pressure sensor. The device demonstrates excellent sensitivity, fast response, and a wide working range from 10 Pa to 10 kPa.Um dos principais objetivos deste trabalho tem em vista uma preocupação da nossa sociedade: Sustentabilidade. Com a degradação do bem-estar e qualidade ambiental do planeta, e sendo um processo cada vez mais irreversível nos últimos anos, só faz sentido concentrar toda a nossa atenção na melhoria da sustentabilidade e na redução do lixo eletrônico, seguindo a visão dos Objetivos de Sustentabilidade das Nações Unidas e do Acordo Verde Europeu. Este trabalho está comprometido com a fabricação de papel eletrónico multifuncional de baixo custo através de lixo reciclado, visado em reduzir o uso de matérias-primas em estado critico. De seguida, o papel eletrónico foi projetado em diversas aplicações de multiuso inteligente como extração de energia através de resposta mecânica, sensores de pressão interativos e siste-mas de armazenamento de energia. Este trabalho tem por base estudos anteriormente desenvol-vidos no CENIMAT e CEMOP. No entanto, este trabalho visa uma abordagem mais ecológica, pois utiliza celulose obtida de jornais usados que não teriam outro destino senão a reciclagem. Todas as amostras recicladas e papel eletrónico foram investigadas através de caracterizações químicas, elétricas e morfológicas. Ao funcionalizar o papel reciclável (RP), este demonstrou boa condutividade como papel eletrónico. O papel eletrónico foi projetado em dispositivos de extração de energia através de resposta mecânica que por sua vez, geraram corrente com um mecanismo de transferência de carga num sistema PANI-celulose/elétrodo. Os dispositivos fabricados, apresentaram resultados satisfató-rios (tensão de saída: 17-20 V, corrente de saída: 0.85 -1.6 μA, densidade de potência: 0.16-0.35 Wm-2) na produção de energia através de impulsos mecânicos, conseguindo acender vários LEDs em série. Posteriormente, o papel eletrónico foi investigado como sensor de pressão flexível. O disposi-tivo demonstrou excelente sensibilidade, resposta rápida e uma larga área de trabalho entre 10 Pa e 10 kPa

Energy Harvesting Technologies for Achieving Self-Powered Wireless Sensor Networks in Machine Condition Monitoring:A Review

Condition monitoring can reduce machine breakdown losses, increase productivity and operation safety, and therefore deliver significant benefits to many industries. The emergence of wireless sensor networks (WSNs) with smart processing ability play an ever-growing role in online condition monitoring of machines. WSNs are cost-effective networking systems for machine condition monitoring. It avoids cable usage and eases system deployment in industry, which leads to significant savings. Powering the nodes is one of the major challenges for a true WSN system, especially when positioned at inaccessible or dangerous locations and in harsh environments. Promising energy harvesting technologies have attracted the attention of engineers because they convert microwatt or milliwatt level power from the environment to implement maintenance-free machine condition monitoring systems with WSNs. The motivation of this review is to investigate the energy sources, stimulate the application of energy harvesting based WSNs, and evaluate the improvement of energy harvesting systems for mechanical condition monitoring. This paper overviews the principles of a number of energy harvesting technologies applicable to industrial machines by investigating the power consumption of WSNs and the potential energy sources in mechanical systems. Many models or prototypes with different features are reviewed, especially in the mechanical field. Energy harvesting technologies are evaluated for further development according to the comparison of their advantages and disadvantages. Finally, a discussion of the challenges and potential future research of energy harvesting systems powering WSNs for machine condition monitoring is made

UltraPower: Powering Tangible and Wearable Devices with Focused Ultrasound

Wireless power transfer creates new opportunities for interaction with tangible and wearable devices, by freeing designers from the constraints of an integrated power source. We explore the use of focused ultrasound as a means of transferring power to a distal device, transforming passive props into dynamic active objects. We analyse the ability to transfer power from an ultrasound array commonly used for mid-air haptic feedback and investigate the practical challenges of ultrasonic power transfer (e.g., receiving and rectifying energy from sound waves). We also explore the ability to power electronic components and multimodal actuators such as lights, speakers and motors. Finally, we describe exemplar wearable and tangible device prototypes that are activated by UltraPower, illustrating the potential applications of this novel technology

Paper-based Screen-printed Passive Electronic Components

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

Blending the Material and Digital World for Hybrid Interfaces

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

Paper-based ZnO self-powered sensors and nanogenerators by plasma technology

Nanogenerators and self-powered nanosensors have shown the potential to power low-consumption electronics and human-machine interfaces, but their practical implementation requires reliable, environmentally friendly and scalable, processes for manufacturing and processing. This article presents a plasma synthesis approach for the fabrication of piezoelectric nanogenerators (PENGs) and self-powered sensors on paper substrates. Polycrystalline ZnO nanocolumnar thin films are deposited by plasma-enhanced chemical vapour deposition on common paper supports using a microwave electron cyclotron resonance reactor working at room temperature yielding high growth rates and low structural and interfacial stresses. Applying Kinetic Monte Carlo simulation, we elucidate the basic shadowing mechanism behind the characteristic microstructure and porosity of the ZnO thin films, relating them to an enhanced piezoelectric response to periodic and random inputs. The piezoelectric devices are assembled by embedding the ZnO films in PMMA and using Au electrodes in two different configurations: laterally and vertically contacted devices. We present the response of the laterally connected devices as a force sensor for low-frequency events with different answers to the applied force depending on the impedance circuit, i.e. load values range, a behaviour that is theoretically analyzed. The vertical devices reach power densities as high as 80 nW/cm2 with a mean power output of 20 nW/cm2. We analyze their actual-scenario performance by activation with a fan and handwriting. Overall, this work demonstrates the advantages of implementing plasma deposition for piezoelectric films to develop robust, flexible, stretchable, and enhanced-performance nanogenerators and self-powered piezoelectric sensors compatible with inexpensive and recyclable supportsComment: 30 pages, 8 figures in main tex

SMART MATERIALS FOR STRETCHABLE ELECTRONICS, SENSORS AND SOFT ACTUATION

Smart materials can be exploited to facilitate disruptive or transformative changes in several fields like stretchable electronics, soft robotics or to develop new class of sensors. They are innovative materials that interact with the environment and respond to external stimuli altering their physical properties in a controlled fashion. They are made integrating different materials at the nanoscale in a nanocomposite to obtain novel functionalities that are not showed from individual constituents. Polymers are the best candidates to be used in smart material fabrication because of their structural and functional properties that can be easily tuned. Moreover, they are low-cost, versatile and can be processed into any shape including thin films. In order to exploit smart materials for soft robotics or stretchable electronic applications, it is required that they should be electrically conductive, patternable, have good mechanical properties and need to be able to transduce an electrical signal in a mechanical response. In addition, their functionalities should remain unchanged over a long period of time. Thus polymers are combined with hard materials like metals, semiconductors or standard electronic components. It is challenging to fabricate technologically relevant smart materials combining hard and soft materials because of their intrinsic physical diversities. Standard manufacturing processes fail to achieve the needed requirements. Among different processes to fabricate smart materials based on polymers, Supersonic Cluster Beam Implantation (SCBI) and Supersonic Cluster Beam Deposition (SCBD) are effective techniques to realize smart materials based on metal/polymer nanocomposites. In my thesis work, I have demonstrated that it is possible to produce new robust smart materials, designing both their electrical and mechanical properties with sharp precision. Metal/polymer nanocomposites have been designed at the nanoscale level to obtain sensors, actuators and electronic devices. Their electrical and mechanical properties have been characterized and their performances have been tested under different stress conditions

A plug and play framework for an HVAC air handling unit and temperature sensor auto recognition technique

A plug and play framework for an HVAC air handling unit control system is proposed in this study. This is the foundation and the first step towards the plug and play HVAC control system that will eventually lead to self-configuring of HVAC control systems for automatic building controls system set-up, commissioning, more robust HVAC system operations, and automatic detection and repair of potential controls problems. This framework is built on the commercially available smart transducers that are compatible with the IEEE 1451 family of standards, and a data acquisition system that can read and write the smart transducer information. As a proof of concept for the framework, a structural pattern recognition algorithm is developed to automatically recognize temperature sensors in an Air Handling Unit (AHU) at different locations. The algorithm can be a critical part of the self-configuring HVAC control system in establishing a binding list of control system input/output and automated assignment and verification of the binding list. A prototype of the plug and play framework for an AHU was built. Experiments were designed, setup, and tested to automatically recognize eleven different temperature sensors at various AHU locations on two different AHUs. More than one hundred test cases were implemented at various initial conditions, environmental temperatures, and chilled water system configurations, to demonstrate the robustness of the pattern recognition algorithm