In this article we investigate the change in wetting behavior of inkjet printed materials on either hydrophilic or hydrophobic plasma treated patterns, to determine the minimum obtainable track width using selective patterned μPlasma printing. For Hexamethyl-Disiloxane (HMDSO)/N2 plasma, a decrease in surface energy of approx. 44 mN/m was measured. This resulted in a change in contact angle for water from <10 up to 105 degrees, and from 32 up to 46 degrees for Diethyleneglycol-Dimethaclylate (DEGDMA). For both the nitrogen, air and HMDSO/N2 plasma single pixel wide track widths of approx. 320 μm were measured at a plasma print height of 50 μm. Combining hydrophilic pretreatment of the glass substrate, by UV/Ozone or air μPlasma printing, with hydrophobic HMDSO/N2 plasma, the smallest hydrophilic area found was in the order of 300 μm as well.
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Nederlandse laagveengebieden vormen voor het habitattype overgangs- en trilvenen een zwaartepunt in Noordwest-Europa. In veel van deze gebieden wordt een negatieve trend van verzuring, verdroging en vermesting waargenomen. Hoe deze systemen precies functioneren en welke bijdrage een verhoogde atmosferische stikstofdepositie heeft op de vegetatiesuccessie in kraggenverlandingen, is echter onbekend. In een OBN-onderzoek zijn 110 locaties met overgangs- en trilvenen in 21 Nederlandse laagvenen bemonsterd voor standplaatsfactoren en vegetatiesamenstelling.
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Renewing agricultural grasslands for improved yields and forage quality generally involves eliminating standing vegetation with herbicides, ploughing and reseeding. However, grassland renewal may negatively affect soil quality and related ecosystem services. On clay soil in the north of the Netherlands, we measured grass productivity and soil chemical parameters of ‘young’ (5–15 years since last grassland renewal) and ‘old’ (>20 years since last grassland renewal) permanent grasslands, located as pairs at 10 different dairy farms. We found no significant difference with old permanent grassland in herbage dry matter yield and fertilizer nitrogen (N) response, whereas herbage N yield was lower in young permanent grassland. Moreover, the young grassland soil contained less soil organic matter (SOM), soil organic carbon (C) and soil organic N compared to the old grassland soil. Grass productivity was positively correlated with SOM and related parameters such as soil organic C, soil organic N and potentially mineralizable N. We conclude that on clay soils with 70% desirable grasses (i.e., Lolium perenne and Phleum pratense) or more, the presumed yield benefit of grassland renewal is offset by a loss of soil quality (SOM and N-total). The current practice of renewing grassland after 10 years without considering the botanical composition, is counter-productive and not sustainable.
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Inkjet printing is a rapidly growing technology for depositing functional materials in the production of organic electronics. Challenges lie among others in the printing of high resolution patterns with high aspect ratio of functional materials to obtain the needed functionality like e.g. conductivity. μPlasma printing is a technology which combines atmospheric plasma treatment with the versatility of digital on demand printing technology to selectively change the wetting behaviour of materials. In earlier research it was shown that with μPlasma printing it is possible to selectively improve the wetting behaviour of functional inks on polymer substrates using atmospheric air plasma. In this investigation we show it is possible to selectively change the substrate wetting behaviour using combinations of different plasmas and patterned printing. For air and nitrogen plasmas, increased wetting of printed materials could be achieved on both polycarbonate and glass substrates. A minimal track width of 320 μm for a 200 μm wide plasma needle was achieved. A combination of N2 with HMDSO plasma increases the contact angle for water up from <100 to 1050 and from 320 to 460 for DEGDMA making the substrate more hydrophobic. Furthermore using N2-plasma in combination with a N2/HMDSO plasma, hydrophobic tracks could be printed with similar minimal track width. Combining both N2 -plasma and N2/HMDSO plasma treatments show promising results to further decrease the track width to even smaller values.
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De toekomst van de zeevaart ziet er volgens Martien Visser zonnig uit. “We hebben weliswaar de ambitie minder afhankelijk te worden van landen van buiten Europa, maar in de praktijk komt daar niets van terecht. We willen zelfs geen datacenters. Extra belangrijk dus te werken aan een CO2-vrije internationale scheepvaart”, stelt hij.
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With a market demand for low cost, easy to produce, flexible and portable applications in healthcare, energy, biomedical or electronics markets, large research programs are initiated to develop new technologies to provide this demand with new innovative ideas. One of these fast developing technologies is organic printed electronics. As the term printed electronics implies, functional materials are printed via, e.g. inkjet, flexo or gravure printing techniques, on to a substrate material. Applications are, among others, organic light emitting diodes (OLED), sensors and Lab-on-a-chip devices. For all these applications, in some way, the interaction of fluids with the substrate is of great importance. The most used substrate materials for these low-cost devices are (coated) paper or plastic. Plastic substrates have a relatively low surface energy which frequently leads to poor wetting and/or poor adhesion of the fluids on the substrates during printing and/ or post-processing. Plasma technology has had a long history in treating materials in order to improve wetting or promote adhesion. The µPlasma patterning tool described in this thesis combines a digital inkjet printing platform with an atmospheric dielectric barrier discharge plasma tool. Thus enabling selective and local plasma treatment, at atmospheric pressure, of substrates without the use of any masking materials. In this thesis, we show that dependent on the gas composition the substrate surface can either be functionalized, thus increasing its surface energy, or material can be deposited on the surface, lowering its surface energy. Through XPS and ATR-FTIR analysis of the treated (polymer) substrate surfaces, chemical modification of the surface structure was confirmed. The chemical modification and wetting properties of the treated substrates remained present for at least one month after storage. Localized changes in wettability through µPlasma patterning were obtained with a resolution of 300µm. Next to the control of wettability of an ink on a substrate in printed electronics is the interaction of ink droplets with themselves of importance. In printing applications, coalescence of droplets is standard practice as consecutive droplets are printed onto, or close to each other. Understanding the behaviour of these droplets upon coalescence is therefore important, especially when the ink droplets are of different composition and/or volume. For droplets of equal volume, it was found that dye transport across the coalescence bridge could be fully described by diffusion only. This is as expected, as due to the droplet symmetry on either side of the bridge, the convective flows towards the bridge are of equal size but opposite in direction. For droplets of unequal volume, the symmetry across the bridge is no longer present. Experimental analysis of these merging droplets show that in the early stages of coalescence a convective flow from the small to large droplet is present. Also, a smaller convective flow of shorter duration from the large into the small droplet was identified. The origin of this flow might be due to the presence of vortices along the interface of the bridge, due to the strong transverse flow to open the bridge. To conclude, three potential applications were showcased. In the first application we used µPlasma patterning to create hydrophilic patterns on hydrophobic dodecyl-trichlorosilane (DTS) covered glass. Capillaries for a Lab-on-a-chip device were successfully created by placing two µPlasma patterned glass slides on top of each other separated by scotch tape. In the second application we showcased the production of a RFID tag via inkjet printing. Functional RFID-tags on paper were created via inkjet printing of silver nanoparticle ink connected to an integrated circuit. The optimal operating frequency of the produced tags is in the range of 860-865 MHz, making them usable for the European market, although the small working range of 1 m needs further improvement. Lastly, we showed the production of a chemresistor based gas sensor. In house synthesised polyemeraldine salt (PANi) was coated by hand on top of inkjet printed silver electrodes. The sensor proved to be equally sensitive to ethanol and water vapour, reducing its selectivity in detecting changes in gas composition.
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In manufacturing of organic electronics, inkjet printing as an alternative technique for depositing materials is becoming increasingly important. Aside to the ink formulations challenges, improving the resolution of the printed patterns is a major goal. In this study we will discuss a newly developed technique to selectively modify the substrate surface energy using plasma treatment as a means to achieve this goal. First, we look at the effects of the μPlasma treatment on the surface energy for a selection of plastic films. Second, we investigated the effects of the μPlasma treatment on the wetting behaviour of inkjet printed droplets to determine the resolution of the μPlasma printing technique. We found that the surface energy for all tested films increased significantly reaching a maximum after 3-5 repetitions. Subsequently the surface energy decreased in the following 8-10 days after treatment, finally stabilizing at a surface energy roughly halfway between the surface energy of the untreated film and the maximum obtained surface energy. When μPlasma printing lines, an improved wetting abillity of inkjet printed materials on the plasma treated areas was found. The minimal achieved μPlasma printed line was found to be 1 mm wide. For future application it is important to increase the resolution of the plasma print process. This is crucial for combining plasma treatment with inkjet print technology as a means to obtain higher print resolutions.
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This paper analyses the initiative AgroAgenda in the northern Netherlands. The AgroAgenda is a platform in which multiple stakeholders together stimulate a circular, and nature-inclusive agro-food system in the Dutch provinces of Friesland, Groningen and Drenthe. Stakeholders come from, among others, provincial governments, farmers’ and nature organizations, educational and research institutes and processing companies. They join forces to realize a system change, a transition, in the region, while promoting knowledge circulation, knowledge co-creation and joint learning. The platform, is a front runner of five national, comparable initiatives. The AgroAgenda has the potential to lead to a more nature-inclusive and circular farming. Several of the 40 experiments have already led to good results. However, to bring about a real system change, more attention to innovations in governmental organizations (including law and regulations), policy, the value chains (division of margins, pricing and marketing) and the educational system are needed.
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The additive manufacturing (AM) of high-quality products requires knowledge of the 3D-printing process and the related design guidelines. Allthough AM has been around for some years, many engineers still lack this knowledge. Therefore, Fontys University of Applied Sciences sets great store by training of engineers, education of engineering students and knowledge sharing on this topic. As an appetiser, this article offers a beginner’s course.
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Deze publicatie is ontwikkeld door het lectoraat Communicatie, Participatie en Sociaal-Ecologisch Leren (CoPSEL) in samenwerking met partneruniversiteiten als een eindresultaat van het Invest4Excellence project. Het magazine onderzoekt de complexiteit en dynamiek van Living Labs door met een drietal metaforen (koken, reizen en Do-It-Yourself) te reflecteren op Living Labs zowel in Nederland, Europa en daarbuiten.
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