Zoekresultaten

µPlasma Patterning and Inkjet Printing to enhance localized wetting and mixing behaviour

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.

Itour

Technology is becoming omnipresent in public spaces: from CCTV cameras to smart phones, and from large public displays to RFID enabled travel cards. Although such technology comes with great potential, it also comes with apparent (privacy) threats and acceptance issues. Our research focuses on realizing technologyenhanced public spaces in a way that is acceptable and useful for the public. This paper gives a brief overview of the research that is aimed to unlock the positive potential of public spaces. This paper’s main focus is on the acceptance of sensor technology in the realm of tourism. The ITour project which investigates the potential and acceptance of using (sensor) technology and ambient media to collect, uncover and interpret data regarding tourists’ movements, behavior and experiences in the city of Amsterdam is particularly discussed as an example.

Mapping welfare

Several studies have suggested that precision livestock farming (PLF) is a useful tool foranimal welfare management and assessment. Location, posture and movement of an individual are key elements in identifying the animal and recording its behaviour. Currently, multiple technologies are available for automated monitoring of the location of individual animals, ranging from Global Navigation Satellite Systems (GNSS) to ultra-wideband (UWB), RFID, wireless sensor networks (WSN) and even computer vision. These techniques and developments all yield potential to manage and assess animal welfare, but also have their constraints, such as range and accuracy. Combining sensors such as accelerometers with any location determining technique into a sensor fusion systemcan give more detailed information on the individual cow, achieving an even more reliable and accurate indication of animal welfare. We conclude that location systems are a promising approach to determining animal welfare, especially when applied in conjunction with additional sensors, but additional research focused on the use of technology in animal welfare monitoring is needed.

Average kWh per RFID per session in the G4 and MRA-E

Contextinformatie verbetert identificatie

We laten steeds meer sporen na: door op internet te surfen, door onze mobiele telefoon te gebruiken, door RFID-labels bij ons te dragen of door ons binnen het blikveld van camera’s te bewegen. Door de contextuele informatie die dit genereert te gebruiken als aanvulling op de ‘klassieke’ methode van gezichtsherkenning kunnen we de identificatie van personen sterk verbeteren. Bob Hulsebosch en Wouter Teeuw van het Telematica-instituut leggen uit hoe. Identificatie is het herkennen van een specifiek persoon – van wie de identiteit bekend is – in de menigte. Gezichtsherkenning speelt hierbij een grote rol. Uit camerabeelden leiden we een aantal gelaatskenmerken af, die we vergelijken met profielen in een database. Een match is mede afhankelijk van de tolerantie die we instellen. Bij een strenge instelling, met weinig ruimte voor onnauwkeurigheid, is de kans klein dat iemand ten onrechte wordt herkend (een lage false acceptance rate, of FAR), maar wordt de kans groter dat iemand uit de database ten onrechte niet wordt herkend (hogere false rejection rate, of FRR).

RFID in Retail: New approaches, new viewpoints

RFID technology is a promising technology currently finding its way into the field of customer interaction strategy, supply chain accuracy and inventory management. Primarily, RFID tags are seen as substitutes of traditional barcodes, yet they can add a lot of value and functionality. Where barcodes require a scanning device to be placed directly in front of the tag to be read, RFID tag readers are able to scan all tags that are in the proximity of the scanner . The next difference is that whereas barcodes usually are the same for all articles of the of the same type (i.e. a jar of peanut butter of brand x), RFID tags will be unique for each individual product occurrence. This opens up the possibility of tracking the entire history of a specific occurrence of a product. Moreover, due to the nature of the scanning technology, it suddenly becomes achievable for manufacturers to track individual products through all stages of production and base inventory management and front office planning on real-time data at item level from production facilities.