<p>Halftoning methods can be divided into two main categories, namely AM (Amplitude Modulated) and FM (Frequency Modulated). Some printing methods, such as Flexography, are not able to produce dots small enough to handle the highlights and the shadows of the original image by just using AM halftoning method. To overcome this problem FM method is used in the highlights (and the shadows) and an AM method in rest of the image.</p><p>Hybrid halftoning (combination of AM and FM) technique for grayscale images has already be presented showing the best way to place FM and AM dots in the resulting binary image. This thesis work is and extension of that and presents hybrid technique for color images. In color images, besides the problem of transition area between AM and FM, a number of other factors needs to be addressed. One of such factors is to define the starting point of FM technique in different color channels. In this work all the possibilities of combining AM and FM in different color channels have been investigated and then the best approach for hybrid color halftoning is proposed. This approach not only uses the best solution for starting point of FM halftoning in each channel but also places the different color dots in the highlights, as homogenously as possible.</p>

<p>Coated solid bleached board belongs to the top-segment of paperboards. One important property of paperboard is the printability. In this diploma work a specific print defect, oriented mottle, has been studied in association with Iggesund Paperboard. The objectives of the work were to develop a method for analysis of the dark and light areas of oriented mottle, to analyse these areas, and to clarify the effect from the print, coating and paperboard surface related factors. This would clarify the origin of oriented mottle and predict oriented mottle on unprinted paperboard. The objectives were fulfilled by analysing the areas between the dark halftone dots, the amount of coating and the ink penetration, the micro roughness and the topography. The analysis of the areas between the dark halftone dots was performed on several samples and the results were compared regarding different properties. The other methods were only applied on a limited selection of samples. The results from the study showed that the intensity differences between the dark halftone dots were enhanced in the dark areas, the coating amount was lower in the dark areas and the ink did not penetrate into the paperboard. The other results showed that areas with high transmission corresponded to dark areas, smoother micro roughness, lower coating amount and high topography. A combination of the information from these properties might be used to predict oriented mottle. The oriented mottle is probably an optical phenomenon in half tone prints, and originates from variations in the coating and other paperboard properties.</p>

<p>Flexographic printing is a process that employs a flexible printing form and low viscous ink, often water-based. The flexible printing form is favourable for printing on rough surfaces, but the high surface tension of the ink may cause printability problems.</p><p>This work has focused on the interaction between paper/paperboard coating and water-based flexographic ink, aimed at increasing the knowledge about the printing process in form of physical/chemical parameters that are important for ink setting. The effects of printing conditions on print quality, such as printing pressure and temperature, have also been in focus.</p><p>The work has shown that fluids of different polarities, i.e. different dipole moments, behave differently when being absorbed by a coating layer. Due to their chemical compatibility to the coating layer, fluids with large dipole moment fill the pore matrix of the coating to a lesser extent but penetrate further into the coating than fluids with small dipole moments. On the other hand, polarity of the coating layer also affects the print. When printing on coatings with different polarities, higher print densities was obtained on the more polar substrates. As a tentative explanation, it is proposed that the ink builds different layer structures during drying depending on the coating polarity.</p><p>Print gloss is related to the ink setting which, in turn, is affected by the solvent retaining capacity of the ink. Large water holding capacity allows the ink components to smoothen out before the structure is set, resulting in a higher print gloss. The rheology of inks is affected by temperature; at a higher temperature the viscosity is reduced. The reduction in ink viscosity at higher temperature has been shown to affect the print quality, e.g., print density and dot gain. It is suggested that a thicker layer is immobilised during impression due to the lower viscosity and that it is an explanation of the higher print density at a higher printing temperature.</p><p>The influence of impression pressure on dot gain has been experimentally evaluated and mathematically modelled with good agreement. The dot gain is shown to respond non-linearly to the applied printing pressure.</p><p>Studies based on pilot coated and printed paperboards is also reported, and it is shown that the print quality, e.g. print density, print gloss and dot gain, is largely dependent on the type of ink chosen and on the coating characteristics. Higher clay content in the coating resulted in increased dot gain and a decreased mottling.</p>

A numerical model has been developed to simulate the firing of an inkjet printhead. The model evaluates the heat generation and diffusion within the thin film structure, the phase change and vapor bubble growth in the ink, and the subsequent flow of ink from the orifice. The heat transfer is modeled numerically throughout the printhead's thin film structure and ink through an asymptotic integration algorithm. The bubble growth and fluid flow are coupled and modeled through conservation of momentum, conservation of energy, and state equations. The heat transfer model has been validated with simple theoretical solutions and ink drop weight and velocity have been compared to empirical data. To test the usefulness of the model as a design tool, parametric studies have been made which characterize pen performance as a function of several system parameters. The results show that although the model does not reflect every detail in the firing process, it is useful for predicting trends and investigating new design concepts. / Graduation date: 1997

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.

Imagine if you could combine the power and capabilities ofan entire laboratory in the palm of your hand. Advances inmicrofluidic chip technology promise to integrate andminiaturize multiple lab processes into a single palm-sizeddevice. The advantages of these lab-on-a-chip devices,sometimes also referred to as micro total analysis systems(µTAS), compared with conventional bench-scale systems arenumerous and wide ranging and include: less reagentconsumption, low manufacturing costs, increased performance,faster analysis, high sample throughput, integration andautomation possibilities, and disposability. However,microfluidic devices also present challenges such as theinterfacing to the macro world and detection limits. In this thesis the focus has been to develop novel discretemicrofluidic components for biotechnology and organic chemicalapplications with the goal to integrate them to formlab-on-chips. A flow-through filter-chamber device has beendesigned, manufactured and evaluated for chemical analysis onbeads. Passive liquid handling has been integrated on the chipin the form of hydrophobic valves at the inlet channels. Anarray format has also been developed to allow parallel analysisof multiple samples. The filter-chamber functions well forsingle nucleotide analysis using pyrosequencing. Initialevaluations on catalyst screening in the filter-chamber devicehas been performed. The suitability of valve-less micropumps for biochemicalapplications is presented. Fluids encountered in variousbiochemical methods, including living cells, that areproblematic for other micropumps have been pumped with goodperformance. This thesis also introduces expandablemicrospheres as a novel component in microfluidics includingapplications such as one-shot valves, micropositioning andsurface enlargement. A novel technique for bead immobilization in microfluidicdevices based on surface chemistry is presented in this thesis.Beads for both biochemical assays and organic chemistry havebeen self-sorted and self-assembled in line patterns as narrowas 5 µm on both structured and unstructured substrates.This method will greatly facilitate the generation of screeningplatforms, for example. To develop a microfluidic device for catalysis-on-chip,ligands for asymmetric catalysis have successfully beenimmobilized in silicon channels by consecutive microcontactprinting, which is a novel technique presented in thisthesis. <b>Keywords:</b>microfluidics, beads, microspheres, silicon,filter-chamber, flow-through, bead trapping, DRIE, passivevalves, fluorocarbon, microfluidic array, adhesive bonding,valve-less micropump, microcontact printing, PDMS,self-assembly, self-sorting, DNA, SNP, pyrosequencing,allele-specific extension, expandable microspheres, catalysis,chiral ligand, monolayer, miniaturization, lab-on-a-chip,µTAS.

Durant la tesi doctoral s'ha comprovat que a partir de biosensors fabricats mitjançant una tecnología relativament senzilla i económica, com és la formació de matrius i la impressió serigràfica de tintes, es poden realitzar determinacions de diversos analits d'interès en l'àmbit alimentari no tan sols en solucions estàndard sinó també en mostres reals. Els resultats aconseguits suposen una important millora en l'abaratiment dels costos d'anàlisi i la reducció del temps necessari.El treball realitzar s'ha portat a terme en dues parts molt diferenciades; en una primera s'han desenvolupat biosensors screen-printing basats en resines epoxi per a l'anàlisi de pesticides i en una segona biosensors screen-printing basats en matrius de sílice (sol-gel) per a la determinació d'àcid màlic i làctic en vins.

Now and in the future we will consider more and more ecological aspects. The car industry already has a strong commitment to environmental care, but I have decided to investigate how we can go a step further. Imagine a car taking advantage of new and upcoming technologies to reduce its footprint. This vehicle will demonstrate a new method to mass produce cars by simplifying the workflow and reduce the amount of component. The main idea is to be energy efficient while you build it and drive it.

Manufactured products, such as furniture, laminate flooring, and large signs, are very labour intensive, time-consuming, and costly to produce as they require multiple coating and cutting operations on a series of independent machines, which can each introduce manufacturing errors between the tools and the work piece. By combining the processes of printing and milling, printing integrated manufacturing has the potential to eliminate some of these steps, significantly reduce errors, and preserve resources. Inkjet printing is an ideal method for both image transfer and coating operations due to its non-contact method of directly depositing various types of fluid onto a substrate. With improved positioning accuracy and droplet miniaturisation, inkjet printing could even be used for future applications like the mass-production of MEMS devices, which are traditionally fabricated with a highly complex process involving photolithography. This thesis presents the integration of a Xaar 126 inkjet printing system with an existing industrial flatbed CNC router to develop a combined printing and cutting system. This integration required modification to the overall system through mechanical, electrical, and software means to the existing 3-axis CNC milling system. A secondary z-axis was installed onto the router gantry for positioning of the printheads relative to the substrate, which required development of a separate homing routine to consistently position the printheads to a specified location. Based on the identified frequency response of the machine, a loop-shaping controller was designed for improved y-axis positioning, which is one of the main contributions to droplet placement accuracy. This resulted in a continuous motion tracking accuracy within ±20.2 µm at 250 mm/sec along a print pass (measured by 1.22 nm resolution linear encoder), which is significantly better than the industrial benchmark of ±100 µm. Extensive image processing and calibration methods were utilised on various substrate preparations of paper, wood, and coatings, to demonstrate the capability of the printing system and quantify the quality of print resolution. Calibration results tested on high-gloss Hewlett-Packard paper showed that the swath angle could be aligned within ±1°. Also, bidirectional printing could be used to reduce print time by at least 15% in multi-colour printing with comparable droplet placement accuracy to unidirectional printing. The inkjet system was successfully used to print custom designs on paper and, to a certain extent, on medium density fibreboard at a feed rate of 250 mm/sec. It was difficult to achieve satisfactory image results on wood, as the wood or paint grain was visible through the ink. Thus, without a white pre-coat, the printed image would appear significantly darker than the original image, even after adjusting the image in a graphics editor. For better quality results, it is recommended that greyscale printheads be implemented for greater resolution and a UV system should be investigated for more versatility in printing on different substrates such as glass, metals, plastics, and ceramics.

Halftoning methods can be divided into two main categories, namely AM (Amplitude Modulated) and FM (Frequency Modulated). Some printing methods, such as Flexography, are not able to produce dots small enough to handle the highlights and the shadows of the original image by just using AM halftoning method. To overcome this problem FM method is used in the highlights (and the shadows) and an AM method in rest of the image. Hybrid halftoning (combination of AM and FM) technique for grayscale images has already be presented showing the best way to place FM and AM dots in the resulting binary image. This thesis work is and extension of that and presents hybrid technique for color images. In color images, besides the problem of transition area between AM and FM, a number of other factors needs to be addressed. One of such factors is to define the starting point of FM technique in different color channels. In this work all the possibilities of combining AM and FM in different color channels have been investigated and then the best approach for hybrid color halftoning is proposed. This approach not only uses the best solution for starting point of FM halftoning in each channel but also places the different color dots in the highlights, as homogenously as possible.