Inkjet-printed memory cards have been developed previously by re-searchers at Mid Sweden University but, these did possess some limita-tions, as each resistive memory cell required one physical contact and the resistances were designed to be electrically programmed.This work overcomes the above limitations by developing chemically programmed printed memory cards and a PC connected memory card reader. Printed memory cards are inexpensive and are developed by inkjet printing the nano-silver ink onto the photo paper substrate. A matrix readout method is used to increase the num-ber of memory cells and, by using a chemical solvent, the resistances were programmed to the desired resistance values and, for which, each resistance value represents data on the cards, called, write once read many (WORM) memories. The memory card reader was developed to access the data (resistance value) of the memory card and also to trans-mit the data to a LabVIEW graphical user interface for displaying the resistance values. By using multiple resistance steps, in which each step represents a different state, it is possible to create a number of possible selectable combinations which can be programmed at a later stage for developing applications.

<div>This thesis includes two parts. The main part is on the topic of conductivity prediction for Inkjet printed silver electrodes. The second part is about the follow-up work of toner usage prediction of laser electro-photographic printers. </div><div><br></div><div>For conductivity prediction of Inkjet printed silver electrodes part, the brief introduction is described below. Recently, electronic devices made with Inkjet printing technique and flexible thin films have attracted great attention due to their potential applications in sensor manufacturing. This imaging system has become a great tool to monitor the quality of Inkjet printed electrodes due to the fact that most thickness or resistance measuring devices can destroy the surface of a printed electrode or even whole electrode. Thus, a non-contact image-based approach to estimate sheet resistance of Inkjet printed electrodes is developed.</div><div><br></div><div>The approach has two stages. Firstly, strip-shaped electrodes are systematically printed with various printing parameters. The sheet resistance measurement data as</div><div>well as images of the electrodes are acquired. Then, based on the real experimental data, the fitting model is constructed and further used in predicting the sheet</div><div>resistance of the Inkjet printed silver electrodes.</div><div><br></div><div>For toner usage prediction part, the introduction is described below. With the widespread use of laser electro-photographic printers in both industry and households fields, estimation of toner usage has great significance to ensuring the full utilization of each cartridge. The follow-up work is focused on testing and improving feasibility, reliability, and adaptability of the Black Box Model (BBM) based two-stage strategy in estimating the toner usage. Comparing with previous methods, the training process for the firrst stage requires less time and disk storage, all while maintaining high accuracy. For the second stage, experiments are performed on various models of printers, with cyan(C), magenta(M), yellow(Y), and black(K) color cartridges.</div>

Os novos processos de impressão têm exigido novas características do papel. Entre os novos processos encontram-se as impressões digitais, em especial, a impressão por jato de tinta. Este tipo de impressão é baseado na ejeção de uma gota de tinta por um orifício em uma cabeça de impressão, que atinge o substrato formando um pixel. A definição das imagens formadas neste tipo de impressão é, portanto, dependente das características da tinta e, principalmente, do substrato. O presente trabalho tem por objetivo caracterizar as propriedades do papel que são importantes para a impressão por jato de tinta, desde o momento em que a tinta atinge a superfície do papel até a sua absorção. As propriedades consideradas neste estudo foram: a rugosidade, a porosidade e as propriedades químicas da superfície. A rugosidade foi avaliada pelos métodos tradicionais da área de papel e celulose (baseados em vazão de ar), por método perfilométrico e, qualitativamente, por imagens obtidas por microscopia eletrônica de varredura (MEV). Para a porosidade foi utilizado um método tradicional, além de porosimetria de intrusão de mercúrio e microtomografia de raios X, e a composição química da superfície foi avaliada por espectroscopia por energia dispersiva (EDS) e espectroscopia Raman. A partir dos resultados obtidos, as propriedades do papel foram qualificadas e as suas influências no espalhamento e absorção de líquidos em geral foram identificadas. Além da caracterização das propriedades superficiais e porosimétricas do papel, as correlações entre as propriedades e os diferentes métodos utilizados na sua determinação foram discutidas. Os métodos de análise tradicional não conseguem caracterizar os papéis em níveis de resolução capazes de fornecer informações sobre a influência das propriedades estudadas na impressão por jato de tinta. Ao mesmo tempo, a caracterização do papel para este tipo de impressão e a compreensão das influências das propriedades do papel no espalhamento e absorção de tinta e líquidos em geral só é possível quando as propriedades são analisadas em conjunto. / The new printing processes have required new features of the paper. Among the new printing processes are the digital printing, in particular, the inkjet printing. This type of printing is based on the ejection of an ink drop through a hole in a print head, which reaches the substrate forming a pixel. The resolution of the images formed in this type of printing is therefore dependent on the characteristics of the ink, and especially of the substrate. The present work aims to characterize the properties of paper that are important to the inkjet printing, from the moment the ink hits the paper surface to its absorption. The properties considered in this study were: roughness, porosity and chemical properties of the surface. The roughness was evaluated by traditional methods in pulp and paper sector (based on air flow), by profilometry and qualitative using images obtained by scanning electron microscopy (SEM). For the porosity, a traditional method was used, and also mercury intrusion porosimetry and X-ray microtomography. The chemical composition of the surface was evaluated by energy dispersive spectroscopy (EDS) and Raman spectroscopy. From the results obtained, the paper properties were described and their influence on the spreading and absorption of liquids in general have been identified. Besides the characterization of the paper surface properties and porosity, the correlations between the properties and the different methods used for measurement were discussed. The traditional analysis methods can not characterize the paper in levels of resolution capable of providing information about the influence of the properties studied in inkjet printing. At the same time, to characterize paper for this printing process and to understand the influences of the paper properties on the spreading and absorption of inks and liquids in general the paper properties have to be analyzed together.

Over the last decade, two dimensional (2D) materials have attracted considerable attention from both the scientific and engineering community due to their unique properties. One important advance of 2D materials is that they can be exfoliated into nanosheets suspended in a liquid phase and that this allows the formulation of 2D nanomaterials inks. Such inks can be deposited as functional components through low-cost inkjet printing techniques. Many 2D materials based inks have been produced over the years. This thesis investigates the use of inkjet printing to deposit 2D materials such as graphene oxide (GO) and black phosphorus (BP).GO, a derivative of graphene, has been widely used to produce graphene-based conductors via inkjet printing owing to its good stability in readily available solvents such as water. In this work, highly conductive reduced graphene oxide (rGO) films with bulk conductivity in excess of 2 × 10^4 Sm-1 have been prepared by inkjet printing a GO aqueous ink, with mean flake size 35.9 micro metre, through a 60 micro metre inkjet printing nozzle followed by a reduction step. Experimental results showed that individual GO flakes up to 200 micro metre diameter can be successfully printed with no instances of nozzle blocking or poor printing performance. The mechanism by which this occurs is believed to be GO sheet folding during drop formation followed by elastic unfolding during drop impact and spreading. In addition, the influence of GO flake size on rGO film conductivity has been investigated. It was found that the rGO film conductivity increased about 60% when the mean flake size of the GO flakes in the ink increases from 0.68 micro metre to 35.9 micro metre. The drying behaviour of printed GO droplets has been studied on eight GO aqueous inks in which the mean flake size of GO was varied over a range from 0.68 to 35.9 micro metre. It was found that the coffee ring effect (inhomogeneous drying of a droplet to leave a ring like deposit) of dried droplets of the GO ink weakened and disappeared when the flake size increasing. It was found that, with a printed deposit around 340 micro metre in diameter, the coffee ring effect (CRE) was suppressed with the mean flake size > 10.3 micro metre. The critical flake size for CRE suppression reduced to 5.97 and 3.68 micro metre when the substrate temperature was 40 and 50 °C, respectively. It was further found that the CRE weakened with decreasing printed drop size, with the critical flake size reducing to 1.58 micro metre with a printed drop diameter of 30 micro metre.The interaction between BP nanometre thickness flakes and humid atmospheres was investigated using an inkjet printed BP sensor. The BP sensor showed was very sensitive to changes in humidity with a response time of a few seconds and the effect is reproducible in minutes. However, long term exposure to humid air with a relative humidity (RH) > 11% leads to a significant chemical change in the BP films, with Fourier transform infra-red spectroscopy (FTIR) indicating partial hydrolysis of the BP to form phosphate and phosphonate ions. Low temperature heat treatment of BP films under dry conditions after exposure to elevated RH leads to a partial recovery of the impedance response and reversion to a chemical state similar to that before exposure to a humid environment. The recovery of BP properties is most complete after exposure to lower humidity environments (RH < 11%), although exact replication of the original impedance response and FTIR spectrum was not possible.

This thesis presents the development of all-inkjet-printed low-voltage organic thin-film transistors. Organic thin-film transistors (OTFTs), taking advantage of low-temperature printability, mechanical flexibility, and multi-functionality, are promising for a wide range of emerging applications such as wearable electronics. Printed OTFTs provide great benefits in fabrication cost reduction, but they need a very high operating voltage and exhibit severe instability during storage and operation in ambient environment. In this study, all-inkjet-printed OTFTs with a low operating voltage of less than 3 V are demonstrated through reducing trap density in the fabricated devices. The transistors use 6,13-bis(triisopropylsilylethynyl)pentacene as the semiconductor, poly(4-vinylphenol) as the dielectric, silver as the electrodes, and CYTOP as the encapsulation. Several aspects of physical and chemical properties of polymer dielectrics are studied to achieve this goal, including cross-linking, wetting, and moisture affinity. Through the careful selection of device architecture and control of the inkjet-printing processes, the semiconductor-dielectric interface trap density of the fabricated OTFTs is significantly reduced. The applicability of this approach to different materials is also investigated and confirmed, including polyvinyl cinnamate as the dielectric, 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene as the semiconductor, and anisole as the solvent for semiconductor inks. Based on the investigation of different materials, the characteristics and parameters of all-inkjet-printed OTFTs are optimised, demonstrating an ultra-steep subthreshold of 60.2 mV/decade approaching the theoretical limit and a low operating voltage of 1 V. In order to explore their feasibility in real-world applications, the stability of all-inkjet-printed OTFTs is investigated and the factors of instability are analysed. Based on these findings, the stability of the fabricated device is improved, such that the threshold voltage shift is less than 0.1 V in ambient environment storage for 3 months and operation for 1 hour. The electrical characteristics of OTFTs in the subthreshold regime are studied for analogue circuit design. Based on the developed low-voltage stable transistors, an ultra-low-power (< 1 nW) high-gain (> 200 V/V) amplifier is presented and utilised to detect electrophysiological signals from the human body.

abstract: Reactive inkjet printing (RIJP) is a direct-write deposition technique that synthesizes and patterns functional materials simultaneously. It is a route to cheap fabrication of highly conductive features on a versatile range of substrates. Silver reactive inks have become a staple of conductive inkjet printing for application in printed and flexible electronics, photovoltaic metallization, and more. However, the high cost of silver makes these less effective for disposable and low-cost applications. This work aimed to develop a particle-free formulation for a nickel reactive ink capable of metallizing highly pure nickel at temperatures under 100 °C to facilitate printing on substrates like paper or plastic. Nickel offers a significantly cheaper alternative to silver at slightly reduced bulk conductivity. To meet these aims, three archetypes of inks were formulated. First were a set of glycerol-based inks temperature ink containing nickel acetate, hydrazine, and ammonia in a mixture of water and glycerol. This ink reduced between 115 – 200 °C to produce slightly oxidized deposits of nickel with carbon content around 10 wt %. The high temperature was addressed in a second series, which replaced glycerol with lower boiling glycols and added sodium hydroxide as a strong base to enhance thermodynamics and kinetics of reduction. These inks reduced between 60 and 100 °C but sodium salts contaminated the final deposits. In a third set of inks, sodium hydroxide was replaced with tetramethylammonium hydroxide (TMAH), a strong organic base, to address contamination. These inks also reduced between 60 and 100 °C. Pipetting or printing onto gold coated substrates produce metallic flakes coated in a clear, thick residue. EDS measured carbon and oxygen content up to 70 wt % of deposits. The residue was hypothesized to be a non-volatile byproduct of TMAH and acetate. Recommendations are provided to address the residue. Ultimately the formulated reactive inks did not meet design targets. However, this thesis sets the framework to design an optimal nickel reactive ink in future work. / Dissertation/Thesis / Masters Thesis Chemical Engineering 2019

Contrairement à l’industrie graphique qui s’est très rapidement convertie à l’impression numérique à jet d’encre, l’industrie textile manifeste de fortes réticences envers cette nouvelle technologie. Ce procédé d’ennoblissement offre pourtant, dans les domaines de la création et de la production, de nombreuses possibilités d’innovation. L’objectif de ce travail est, d’une part de mettre en exergue le potentiel créatif iconographique de cette technologie et d’expliquer les changements de la notion de dessin textile qu’il induit. D’autre part, en les confrontant aux limites actuelles de l’impression traditionnelle aux cadres, il détaille les nouveaux modes de production à même d’insuffler une nouvelle dynamique aux métiers de l’impression textile. En dernier lieu, sont exposés les facteurs environnementaux qui seront appelés à jouer un rôle de plus en plus important dans l’économie du futur. L’ensemble offre ainsi une présentation complète et actualisée des différents aspects de l’impression textile à jet d’encre. / Contrary to the graphics industry that very quickly adopted the digital inkjet printing, the textile industry is very reticent to move into this new technology. Nevertheless, this printing process offers many opportunities for innovation in the fields of design and production. There are three main objectives to this study. The first is to focus on the creative potential of this technology and to explain the changes of textile design thereby induced. The second is to present the new production methods and to compare them to the current limitations of conventional screen printing. These methods will be able to inspire new dynamics in the textile printing industry. The third objective is to expose the environmental factors that will become more and more important in the future economy. The combination of these elements will provide a global and modern picture of the different aspects of textile inkjet printing.

In this thesis investigations are carried out on two research topics in context to spray drying. The first research topic is the production of dried particles having uniform characteristics. The second research topic is the development of new applications of the reaction engineering approach which, in recent times, has emerged as an effective tool to formulate drying kinetics models. The reaction engineering approach is also implemented to simulate the drying of monodisperse droplets corresponding to the experimental work in the first research topic. Manufacturing micron- and nano-sized particles having uniform characteristics has recently become a popular research area due to the unique functionalities of these kinds of particles in biomedical, drug delivery, functional foods, nutraceuticals, cosmetics and other valuable applications. Spray drying has been a common and economical route to produce dried particles. A typical characteristic of spray dried products is the existence of a significant variation in particle properties such as size and morphology. One possible idea to restrict this product non-uniformity is to achieve a good control over the droplet’s behaviour and characteristics inside the drying chamber. The current thesis has investigated an innovative spray drying technique, i.e. a single stream drying approach in order to restrict product non-uniformity. In this drying approach, identical sized droplets having vertical trajectories are dried under controlled gas flow conditions. The piezoelectricity-driven monodisperse droplet generator is used as the atomizer to disperse liquid droplets. A prototype single stream dryer was assembled based on the single stream drying approach using various components designed in the laboratory and several parts purchased from the market. Experiments were carried out using aqueous lactose solutions as a model system in order to check the practicability of manufacturing uniform-sized spherical particles. Preliminary results were found to be positive and reported in this thesis. Mathematical models on the drying of monodisperse droplets were developed in order to predict important droplet and gas parameter profiles during single stream drying. These models serve as a platform for design, optimization and scale-up purposes. Several important advantages and drawbacks of single stream drying are also reported. Problems encountered during the experimental work and future recommendations are presented in detail so that a more robust and effective drying research tool can be developed in future. Recently the reaction engineering approach (REA) has emerged as a simple and reliable technique to characterize the drying of various food and dairy materials. In this thesis two new applications of the REA are described for the first time in context to convective drying of aqueous droplets. The REA is used in this study to formulate the drying kinetics model for the drying of aqueous sucrose and maltodextrin (DE6) droplets. The effect of initial moisture content was explicitly demonstrated. The development of a new ‘composite’ REA which aimed to model the drying of aqueous droplets containing multiple solutes has been described. The composite REA was found to be suitable to characterize the drying behaviour of aqueous sucrose-maltodextrin mixtures of different proportions. The second new application of the REA is the development of a procedure to estimate surface properties of aqueous droplets during drying. In literature various droplet characteristics such as surface moisture contents were normally estimated using the diffusion-based drying kinetics model or the receding interface model. Surface moisture content and surface glass transition temperature profiles were evaluated here using a lumped-parameter model (REA) during the drying of aqueous sucrose, maltodextrin (DE6) and their mixtures. The same experimental data used for the development of the composite REA were used to yield predictions. The procedure was found to be useful in estimating surface moisture contents and understanding the stickiness behaviour of sugar droplets during drying. During the formulation of the REA-based drying kinetics model in this thesis, the assumption of uniform temperature within droplets was used. In most studies published in literature the uniform temperature assumption was justified by calculating the heat-transfer Biot numbers at the beginning and end of drying. However, the conventional Biot number concept does not take into account the evaporation effect and therefore would not be suitable to drying scenarios. In this thesis, a new approximation procedure is developed to estimate surface-centre temperature differences within materials following the entire drying process. This new procedure was helpful to check the extent of temperature non-uniformity within skim milk droplets under isothermal laboratory conditions as well as industrial spray drying conditions. Both conventional and drying-based Biot numbers are calculated and compared. Predictions showed that temperature gradients within the droplets were negligible during the drying of suspended droplets under laboratory drying conditions (slow drying), whilst the gradients were small and existed only for a short drying period for small droplets under industrial spray drying conditions (fast drying). Furthermore, it was observed that the maximum temperature gradient within the droplets did not exist at the starting or end points of the drying process, and therefore the estimation of Biot numbers at the starting and end point does not reflect temperature non-uniformity under drying conditions. This is a significant theoretical development in the area.

<p>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.</p><p>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.</p> / <p>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.</p><p>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.</p><p>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.</p><p>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.</p>

<p>Inkjet is a digital printing process where the ink is ejected directly onto a substrate from a jet device driven by an electronic signal. Most inkjet inks have a low viscosity and a low surface tension, which put high demands on the coating layer’s porosity and absorbency characteristics.</p><p>The aim of this study has been to gain an increased knowledge of the mechanisms that control the sorption and fixation of inkjet inks on coated papers. The focus has been on printability aspects of high print quality (although not photographic quality) laboratory-coated inkjet papers for printers using aqueous-based inks.</p><p>Papers coated solely with polyvinyl alcohol (PVOH) and starch presented excellent gamut values and good print sharpness over the uncoated substrate, due to good film-forming characteristics observed by light microscopy and ESCA. ESEM analyses showed the complexity and variation of PVOH surface structures, which has probably explained the wide scatter in the colour-to-colour bleed results. Pure PVOH coatings also gave a surface with high gloss variations (2-8 times greater than that of commercial inkjet papers), prolonged ink drying time, and cracked prints when using pigmented inks. When an amorphous silica gel pigment (with broad pore size distribution) was used in combination with binder, a new structure was formed with large pores in and between the pigments and a macro-roughness generated by the large particles. The inkjet ink droplets could quickly penetrate into the large pores and the time for surface wicking was reduced, which was beneficial for the blurriness. However, the macro-roughness promoted bulk spreading in the coarse surface structure, and this tended to increase the line width. Finally, when the ink ends up within the coating, the colorant is partly shielded by the particles, and this reduced the gamut area to some extent. The binder demand of the silica pigments was strongly related to their pore size distributions. Silica gel required two to three times the amount of binder compared to novel surfactant-templated mesoporous silica pigments (with small pores and narrow pore size distribution). This finding was attributed to the significant penetration of PVOH binder into the pores in the silica gel, thereby, increasing its binder demand. Furthermore, this binder penetration reduced the effective internal pore volume available for rapid drainage of the ink vehicle. Consequently, the surfactant-templated pigments required significantly lower amounts of binder, and gave improvements in print quality relative to the commercial pigment.</p>