ACPEL devices were fabricated onto various paper substrates. The dielectric and phosphor layers were mask printed, a PEDOT:PSS/SWCNT ink was inkjet-printed for the cathode and a translucent conductor was applied with a paintbrush for the anode resulting in a maximum luminance of 8.05 cd/m2 at 300 VAC and 60 Hz. It was found that the conductivity of the PEDOT:PSS/SWCNT ink on the various paper types was affected by the coating and paper thickness. Novel ACPEL devices were also fabricated by incorporating paper as the dielectric layer of the device. The maximum luminance achieved was 7.24 cd/m2 at 300 VAC and 60 Hz. It is shown that the dielectric constant of the paper and hence the performance of the resulting EL device may be enhanced by filling the sheet with BaTiO3 and by the surface treatment of the sheet.

ACPEL devices were fabricated onto various paper substrates. The dielectric and phosphor layers were mask printed, a PEDOT:PSS/SWCNT ink was inkjet-printed for the cathode and a translucent conductor was applied with a paintbrush for the anode resulting in a maximum luminance of 8.05 cd/m2 at 300 VAC and 60 Hz. It was found that the conductivity of the PEDOT:PSS/SWCNT ink on the various paper types was affected by the coating and paper thickness. Novel ACPEL devices were also fabricated by incorporating paper as the dielectric layer of the device. The maximum luminance achieved was 7.24 cd/m2 at 300 VAC and 60 Hz. It is shown that the dielectric constant of the paper and hence the performance of the resulting EL device may be enhanced by filling the sheet with BaTiO3 and by the surface treatment of the sheet.

Multifunctional composites have gained significant interest as they enable the integration of sensing and communication capabilities into structural, lightweight composites. Researchers have explored additive manufacturing processes for creating these structures through selective patterning of electrically conductive materials onto composites. Thus far, multifunctional composite performance has been limited by the conductivity of functional materials used, and the methods of integration have resulted in compromises to both structural and functional performance. Integration methods have also imposed limitations on part geometry due to an inability to adequately deposit conductive material over concave surfaces. Proposed methods of integrating functional devices within composites have been shown to negatively affect their mechanical performance. This work presents a novel method for integrating printed electronics onto the interior surfaces of closed, complex continuous fiber composite structures via the transfer of selectively printed conductive inks from additively manufactured sacrificial tooling to the composite surface. The process is demonstrated by creating multifunctional composites via embossing printed electronics onto structural composites without negatively affecting the mechanical performance of the structure. Additionally, this process expands the ability to pattern devices onto complex surfaces and demonstrates that the transferred functionality is well integrated (adhered) with the composite surface. The process is further validated through the successful completion of two separate case studies. The first is the integration of a functioning strain gauge onto an S-glass/epoxy composite, while a second process demonstration shows a composite surface featuring a band stop filter at the X-band, otherwise known as a frequency selective surface (FSS), to show the process' suitability for high performance, aerospace grade multifunctional composites. / Master of Science / Significant interest has been given in the past few decades to strong, lightweight materials for structural purposes. Among these materials, specific interest has been paid to fiber-reinforced composites, which are made of strong fibers and advanced resins. Recently, researchers have tried to use electrically conductive inks and 3D printing techniques to put antennas and other devices onto composites. These composites could possess additional functions beyond their structural purpose and are therefore called multifunctional composites. So far, the performance of multifunctional composites has been limited by the methods used to add additional functions. These methods often result in a weaker composite material and poor performance of the added devices. In this work, a new method for integrating devices onto complex-shaped composite structures is demonstrated. This is done by printing a mold for a composite, then putting a conductive ink onto the mold and transferring the ink to the composite surface. This process is demonstrated without weakening the composite. Additionally, this process allows researchers to put devices onto complex surfaces and demonstrates that the devices are secured to the composite surface. The process is used to make two separate devices and combine them with a composites surface. The first demonstration is the integration of a functioning strain gauge (used to measure a change in material dimension) onto a structural composite, while a second process demonstration shows a composite surface featuring an electromagnetic filter, otherwise known as a frequency selective surface (FSS), to show the process' suitability for high performance, aerospace grade multifunctional composites.

This thesis presents novel solutions for the fabrication of functional magnetoresponsive systems, with a focus on the development of magnetic composites as sensors and actuators. Currently, there is a need for multifunctional mechanically flexible materials that can be easily processed into functional devices that respond to a wide range of physical stimuli, including magnetic fields. These characteristics aim for lightweight, and imperceptible systems that help us to interact with technology and with each other without the need for a bulky gadget. Typically, magnetically responsive devices are constructed using materials that do not necessarily possess flexible properties; so magnetosensitive composites with tailored magnetic, conductive, and flexible properties arising from the combination of their constituents were implemented. Here, it is described the use of these composites as printable sensors for magnetic field detection, with a focus on interactivity, safety, and holographic-like applications. A dedicated selection of materials and fabrication methods allowed to obtain stretchable, transparent, or self-healing properties, as well as explore their possibilities for printing them over large-area or even 3D printing. Additionally, it is shown the use of these magnetoresponsive composites as actuators, demonstrating their potential use in magnetic soft robotics by laminating magnetically sensitive devices that give them a sense of motion. Such applications become more technically accessible after the proposition of measurement strategies that remove artifacts in the magnetic signal coming from mechanical deformations. This thesis addressed several of the challenges related to cost, fabrication, and integration in magnetoresponsive composites, and is expected that related research might develop through multifunctional composites that sense more than magnetic fields.

Fundamental research to implement the printed autonomous wireless sensor platform is studied in three aspects: fabrication method, material selection, and novel applications for autonomous sensing/communication. Additive fabrication processes, such as inkjet printing technology and electroless electroplating, are discussed and the additively created metal layers are characterized. Fundamentals for material characterization utilizing resonators are presented and electrical properties of flexible low-cost substrates like synthetic Teslin paper and Poly(methyl methacrylate) (PMMA) are characterized. Widely used flexible substrates for printing, such as Liquid Crystal Polymer (LCP) and Kapton (polyimide), are summarized and tabulated as well. Novel antenna-based applications for efficient and autonomous operation of wireless sensor system, such as an antenna on Artificial Magnetic Conductor (AMC) for wearable applications, an active beacon oscillator for Wireless Power Transfer (WPT), and a multiband RF energy harvester, are designed and their performances are experimentally verified. The printed RFID-enabled sensor topologies with/without RFID chip are discussed as a new sensor platform for autonomous wireless operation. Fully inkjet-printed via topology for system miniaturization and integration is proposed for the first time. Challenges, circuit modeling and experimental data are presented. Future and remaining work to implement the novel low-cost autonomous wireless sensor platform are also discussed.

Sensor applications are becoming increasingly important as products are now being requested to be more and more intelligent and safe. As the costs involved in sensor technology decrease its usage will spread to new market segments including new areas with products that have never previously used such functionalities, including, wood fibre based products for packaging, hygiene or graphical use. Currently there is a significant interest in developing technology that will allow packages to become interactive and be integrated with digital services accessible on the Internet. In this thesis, the system integration of a hybrid RFID based sensor platform is presented. This proposed platform provides a trade-off between the communication performance and its compatibility with international standards and also includes flexibility in on‐package customization, including the type and number of sensors. In addition it combines the use of traditional silicon based electronics with printed electronics directly onto wood fibre based materials so as to enable the possibility of creating smart packages. Together with the system integration of the sensor platform, five printed moisture sensor concepts that are designed to work with the sensor platform are presented and characterized. Firstly, there is a moisture sensor that shows a good correlation to the moisture content of wood fibre based substrates. The second one involves a sensor that detects high relative humidity levels in the air and the third is an action activated energy cell that provides power when activated by moisture. The fourth one deals with two types of moisture sensors that utilize silver nano-particles in order to measure the relative humidity in the air. The final one is a printable touch sensitive sensor that is sensitive to the moisture contained in the hand. A concept of remote moisture sensing that utilizes ordinary low cost RFID tags has also been presented and characterized. The main focus is thus on system integration to, by combining silicon based electronics with printed electronics, find the most low cost solution with regards to flexibility, sensor functions and still meet the communication standards. / När efterfrågan på mer intelligenta och säkra produkter ökar så ökar även intresset för olika typer av sensorer. När kostnaden för dessa sensorer sjunker så kommer användandet av dessa att utökas till nya marknadssegment som tidigare inte använt denna typ av funktionalitet, som tillexempel pappersbaserade förpackningar, hygienartiklar och papper för grafiskttryck. Det är för närvarande ett stort intresse att utveckla tekniker som tillåter förpackningar att bli interaktiva och integrerade med olika digitala tjänster kopplade till Internet. I denna avhandling så presenteras systemintegrationen av en RFID baserad sensor plattform som tillhandahåller en avvägning mellan kommunikationsprestanda, kompabilitet med internationella standarder och kundanpassningsflexibilitet. Där man direkt på förpackningen kombinerar fördelarna med traditionell kiselbaserad elektronik med trycktelektronik för att kunna skapa intelligenta förpackningar. I avhandlingen presenteras och utvärderas även fem trycka fuktsensorer som är designade att kunna användas tillsammans med sensor plattformen. Den första sensorn mäter fukthalten i cellulosabaserade substrat. Den andra kan detektera höga fukthalter i luften. Den tredje, som aktiveras vid en händelse, producerar en elektrisk ström när den blir fuktig. Den fjärde sensorn använder sig av silverbaserade partiklar i nanostorlek för att mäta fukthalten i luften. Den femte sensorn är en beröringskänslig sensor som ger utslag av fukten i handen. Utöver dessa sensorer så utvärderas även ett koncept med en fuktsensor som kan läsas av på avstånd. Fokus är således att på system integrationsnivå, med hjälp av att kombinera kisel elektronik med tryckt elektronik, hitta den mest kostnadseffektiva lösningen med avseende på flexibilitet, sensor funktionalitet och att även kunna möta kommunikationsstandarderna.

In this thesis, a number of commercially available paper substrates of various types are characterized and their characteristics related to the performance of inkjet-printed conductors using silver nanoparticle ink. The evaluated performance variables are electrical conductivity as well as the minimum achievable conductor width and the edge raggedness. It is shown that quick absorption of the ink carrier is beneficial for achieving well defined conductor geometry and high conductivity. Surface roughness with topography variations of sufficiently large amplitude and frequency is detrimental to print definition and conductivity. Porosity is another important factor, where the characteristic pore size is much more important than the total pore volume. A nearly ideal porous coating has large total pore volume but small characteristic pore size, preferably smaller than individual nanoparticles in the ink. Apparent surface energy is important for non-absorbing substrates but of limited importance for coatings with a high absorption rate.Additionally, a concept for improving the geometric definition of inkjet-printed conductors on nonporous films has been demonstrated. By coating the films with polymer–based coatings to provide a means of ink solvent removal, minimum conductor width were reduced a factor 2 or more.Intimately connected to the end performance of printed conductors is a well adapted sintering methodology. A comparative evaluation of a number of selective sintering methods has been performed on paper substrates with different heat tolerance. Pulsed high-power white light was found to be a good compromise between conductivity performance, reliability and production adaptability.The purpose of the work conducted in this thesis is to increase the knowledge base in how surface characteristics of papers and flexible films affect performance of printed nanoparticle structures. This would improve selection, adaption of, or manufacturing of such substrates to suit printed high conductivity patterns such as printed antennas for packaging. / I denna avhandling har ett antal kommersiellt tillgängliga papper av olika typ karaktäriserats och deras egenskaper relaterats till prestandan på inkjet-tryckta elektriska ledare tryckta med silvernanopartikelbläck. De undersökta prestandavariablerna är elektrisk ledningsförmåga samt ledarnas minimala linjebredd och kantjämnhet. Det visas att en snabb absorption av bläckets lösningsmedel är gynnsam för både väldefinierad ledningsgeometri och elektrisk ledningsförmåga. Ytråhet med topografiska variationer med tillräckligt stor amplitud och spatiell frekvens korrelerar negativt med tryckdefinition och ledningsförmåga. Porositet är ytterligare en viktig faktor, där karaktäristisk porstorlek är avsevärt viktigare än total porvolym. Nära ideala egenskaper hos en porös bestrykning synes vara en mycket hög total porvolym men med små individuella porer, med fördel mindre än de minsta metallpartiklarna i bläcket. Ytenergi är mycket betydelsefull för icke-absorberande substrat men tappar nästan all sin betydelse för bestrykningar med snabb absorption.Ett koncept för att förbättra den geometriska definitionen på inkjet-tryckta ledare på icke-porösa flexibla filmer har visats. Genom att bestryka filmerna med vissa polymerbaserade material och därmed införa en mekanism för separering av lösningsmedel och partiklar så reducerades ledarnas minimibredd med en faktor 2 eller mer.Intimt förknippad med den slutliga elektriska prestandan på tryckta ledare är också en väl anpassad sintringsmetodik. En jämförande utvärdering av ett flertal selektiva sintringmetoder har genomförts på papper med olika värmetålighet. Pulsat vitt ljus med hög effekt bedömdes som en bra kompromiss mellan elektriska prestanda, tillförlitlighet och anpassningsbarhet för produktionsmiljö.Nyttan med arbetet som presenteras i denna avhandling är att öka kunskapsbasen för hur pappers och flexibla filmers ytegenskaper påverkar prestandan på inkjet-tryckta nanopartikelstrukturer. Detta möjliggör bättre urval, anpassning av, eller tillverkning av sådana substrat för att passa tryckta mönster med hög konduktivitet; som till exempel tryckta antenner på förpackningar.

This work presents a novel means of producing thin-film light-emitting devices, functioning according to the principle of electroluminescence, using an inkjet printing technique. This study represents the first report of a light-emitting device deposited completely by inkjet printing. An electroluminescent species, doped zinc sulfide, was incorporated into a polymeric matrix and deposited by piezoelectric inkjet printing. The layer was printed over other printed layers including electrodes composed of the conductive polymer poly(3,4-ethylenedioxythiophene), doped with poly(styrenesulfonate) (PEDOT:PSS) and single-walled carbon nanotubes, and in certain device structures, an insulating species, barium titanate, in an insulating polymer binder. The materials used were all suitable for deposition and curing at low to moderate (<150°C) temperatures and atmospheric pressure, allowing for the use of polymers or paper as supportive substrates for the devices, and greatly facilitating the fabrication process. The deposition of a completely inkjet-printed light-emitting device has hitherto been unreported. When ZnS has been used as the emitter, solution-processed layers have been prepared by spin-coating, and never by inkjet printing. Furthermore, the utilization of the low-temperature-processed PEDOT:PSS/nanotube composite for both electrodes has not yet been reported. Device performance was compromised compared to conventionally prepared devices. This was partially due to the relatively high roughness of the printed films. It was also caused by energy level misalignment due to quantization (bandgap widening) of the small (<10 nm) nanoparticles, and the use of high work function cathode materials (Al and PEDOT:PSS). Regardless of their reduced performance, inkjet printing as a deposition technique for these devices presents unique advantages, the most notable of which are rapidity of fabrication and patterning, substrate flexibility, avoidance of material wastage by using drop-on-demand technology, and the need for only one main unit operation to produce an entire device.

This work presents a novel means of producing thin-film light-emitting devices, functioning according to the principle of electroluminescence, using an inkjet printing technique. This study represents the first report of a light-emitting device deposited completely by inkjet printing. An electroluminescent species, doped zinc sulfide, was incorporated into a polymeric matrix and deposited by piezoelectric inkjet printing. The layer was printed over other printed layers including electrodes composed of the conductive polymer poly(3,4-ethylenedioxythiophene), doped with poly(styrenesulfonate) (PEDOT:PSS) and single-walled carbon nanotubes, and in certain device structures, an insulating species, barium titanate, in an insulating polymer binder. The materials used were all suitable for deposition and curing at low to moderate (<150°C) temperatures and atmospheric pressure, allowing for the use of polymers or paper as supportive substrates for the devices, and greatly facilitating the fabrication process. The deposition of a completely inkjet-printed light-emitting device has hitherto been unreported. When ZnS has been used as the emitter, solution-processed layers have been prepared by spin-coating, and never by inkjet printing. Furthermore, the utilization of the low-temperature-processed PEDOT:PSS/nanotube composite for both electrodes has not yet been reported. Device performance was compromised compared to conventionally prepared devices. This was partially due to the relatively high roughness of the printed films. It was also caused by energy level misalignment due to quantization (bandgap widening) of the small (<10 nm) nanoparticles, and the use of high work function cathode materials (Al and PEDOT:PSS). Regardless of their reduced performance, inkjet printing as a deposition technique for these devices presents unique advantages, the most notable of which are rapidity of fabrication and patterning, substrate flexibility, avoidance of material wastage by using drop-on-demand technology, and the need for only one main unit operation to produce an entire device.

Printed electronics (PE) is a disruptive but growing technology that is beginning to integrate its way into viable applications for product design. However, the potential for future impact of the technology on product design and the designer s role and contribution to this has yet to be established. Interest is increasing in the potential for product designers to explore and exploit this technology. Technologies can be seen as being disruptive from both a business, and an adoption point of view. For a business, changing from one technology to another or incorporating a new technology and its production processes can be difficult if they already have their suppliers established and existing relationships in place. Understanding and adopting a new technology can be challenging for a business and individuals working within an established industry as it can cause many questions to be raised around its performance, and direct comparison with the technology they already have in place. However, there have been many technologies that could be seen as disruptive in the past, as they offered an alternative way of working or method of manufacture, such as Bluetooth, 3D printing, and automation (manufacturing/assembly/finishing), etc., and their success has been dictated by individual s perception and adoption of the technology, with their ability to see the worth and potential in the technology. Cost comparison is also an important aspect for a business to consider when choosing whether to change to a new technology or to remain with their existing technology, as changing can disrupt the manufacturing line assembly of a product, and direct cost comparisons of components themselves, such as the cost of buying silicon components in bulk verses printing the components. The new technology needs to offer something different to a product to be worth implementing it in a product, such as its flexible form or lightweight properties of printed electronics being of benefit to the product over what a silicon electronic component/circuit could offer (restricted to rigid circuit boards), the functionality/performance of the components themselves also need to be considered. Performance, availability and maturity of the technology are some of the essential aspects to consider when incorporating a new technology into a product and these can be evaluated using a Technology Readiness Level (TRL) scale. Interest in the stage of development for a technology lies not only with designers; industry and academia also contribute to knowledge by playing a central role in the process of determining a TRL scale that is universally recognised. However, a TRL separation issue occurs between academia (often the technology only reaching an experimental proof of concept stage, a lower number on the TRL scale indicating that the technology is at an early stage of development) and industry (not considering technology for commercialisation until it reaches a stage where there is a demonstration of pre-production capability validated on economic runs, a much higher number on the TRL scale - indicating that the technology is at a much more advanced stage of development). The aim of this doctoral research was to explore the contribution of PE to product design. The researcher experienced the scientific development of the technology first-hand, and undertook a literature review that covered three main topics: 1) printed electronics (the technology itself), 2) impact (approaches to assessing impact and methods of judging new technology) because together they will identify the state of the art of printed electronics technology, and 3) education - educational theories/methods for designers - studying how designers learn, explore different methods in educating them about new technologies, and start to find appropriate methods for educating them about printed electronics technology. A knowledge framework for PE technology was generated and utilised to produce a taxonomy and TRL scale for PE and confirmed by PE expert interview. Existing case studies in which PE technology had been presented to student designers were investigated through interviews with participants from academia and industry to solicit perception and opinions on approaches for the effective communication of PE knowledge to student designers within an educational environment. The findings were interpreted using thematic analysis and, after comparing the data, three main themes identified: technical constraints, designer s perspective, and what a designer is required to do. The findings from the research were combined to create an educational approach for knowledge transfer aimed specifically at meeting the needs of product designers. This resulted in the need for PE technology to be translated into both a visual and written format to create structure and direct links between the technological elements and their form and function in order to facilitate understanding by designers. Conclusions from the research indicate that the translation of this technology into an appropriate design language will equip designers with accessible fundamental knowledge on PE technology (i.e. electrical components: form, function, and area of the technology), which will allow informed decisions to be made about how PE can be used and to utilise its benefits in the design of products. The capabilities and properties of this technology, when paired with product design practice, has the capacity to transform the designs of future products in terms of form/functionality and prevailing/views towards design approaches with electronics. If exposed to a variety of PE elements ranging across different TRLs, designers have the capacity to bridge the TRL separation issue (the gap between academia and industry) through their ability to create design solutions for an end user and provide a commercial application for the technology.