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Während keramische Bremsscheiben bereits als Serienbauteile in High Class-Fahrzeugen verbaut werden, befindet sich die Entwicklung von keramischen Bremsbelägen noch im Anfangsstadium. Im Rahmen des BMBF-Projekts «Anforderungsgerechte hochdrapierbare Carbon-Gelege-Faser-Preformen für effiziente Faserverbundkeramiken - CaGeFa» wurden textile Preformen entwickelt, die eine Reduzierung von Prozesszeiten und -kosten bei gleichzeitiger Optimierung des Eigenschaftsprofils ermöglichen und die Kommerzialisierung keramischer Reibbeläge vorantreiben. Die Bauteile müssen dabei einen hohen, stabilen Reibwiderstand, ein schnelles, effektives Ansprechen (sog. «Initial Bite») sowie eine gezielte Wärmeabführung zur Vermeidung der Überhitzung aufweisen.

The subthalamic nucleus (STN) plays a crucial role in the surgical treatment of Parkinson’s disease (PD). Studies investigating optimal protocols for STN visualization using state of the art magnetic resonance imaging (MRI) techniques have shown that susceptibility weighted images, which display the magnetic susceptibility distribution, yield better results than T1-weighted, T2-weighted, and T2*-weighted contrasts. However, these findings are based on young healthy individuals, and require validation in elderly individuals and persons suffering from PD. Using 7T MRI, the present study set out to investigate which MRI contrasts yielded the best results for STN visualization in 12 PD patients and age-matched healthy controls (HC). We found that STNs were more difficult to delineate in PD as reflected by a lower inter-rater agreement when compared to HCs. No STN size differences were observed between the groups. Analyses of quantitative susceptibility mapping (QSM) images showed a higher inter-rater agreement reflected by increased Dice-coefficients. The location of the center of mass of the STN was not affected by contrast. Overall, contrast-to-noise ratios (CNR) were higher in QSM than in T2*-weighted images. This can at least partially, explain the higher inter-rater agreement in QSM. The current results indicate that the calculation of QSM contrasts contributes to an improved visualization of the entire STN. We conclude that QSM contrast is the preferred choice for the visualization of the STN in persons with PD as well as in aging HC.

The electrical conductivity of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) was enhanced by dipping the thin films prepared by spin coating technique in an aqueous DMSO solution. The low concentration range of DMSO in water between 0-5 vol % was studied in comparison with pure water and pure DMSO. It was found that the electrical conductivity dramatically increased as increasing the concentration of DMSO and reached the constant value of 350 S cm-1 at 2 vol % of aqueous DMSO solution. This could be explained by the conformational change of PEDOT chains from the coil structure to the linear or expanded coil structure as confirmed by Raman spectra. Further, white patches were obviously noticed on the surface of the films dipped in pure DMSO, indicating the phase separation of conductive PEDOT grains and associated PSS. The sulfur element of the dipped film surface was investigated by XPS. The XPS S2p core-level spectra displayed that the unassociated PSS was considerably removed from the surface of PEDOT:PSS films dipped in pure water and 2 vol % of aqueous DMSO solution, indicating that the presence of water in the solvents is important to prominently promote the washing effect. Finally, UV-Vis spectra revealed the improved transparency of the films probably owing to the decreased film thickness.

Inkjet printing of various nanoparticle inks, made from silver or copper nanoparticles, and its transformation into solid functional patterns is of high interest in the field of printed electronics. Liquid materials can be deposited as defined patterns in selected areas with micrometer precision. To convert these printed liquid films, consisting of solvents, additives and nanoparticles, into solid functional patterns a post-treatment is required. To this date, many investigations report on various sintering techniques to achieve e.g. high conductivity from the printed conductive materials. Direct thermal sintering (via furnace or hotplate) requires high temperatures, which makes it not suitable for sensitive polymeric substrates. The novel method of intense pulsed light (IPL) sintering opens the window of opportunity to convert liquid or dried metal layers into solid functional layers within milliseconds without damaging the thermally fragile polymeric substrate. In this work we present and analyze the application of the IPL sintering on inkjet printed silver patterns on various flexible substrates, like Poly(ethylene naphthalate) (PEN), Poly(ethylene terephthalate) (PET), Polyimide (PI) foils and paper. A high dependency of the electrical and structural performance of the printed silver layers on the base substrate was observed when flashing with the IPL technique. Flashing parameters were varied and the resulting sheet resistance is presented. With the analytical comparison of optical and electrical results, the flashing settings could be adapted to achieve highly conductive inkjet printed silver patterns on flexible substrates, when compared to other thermal sintering techniques. Furthermore the first integration of this post treatment methodology into semi-industrial roll-2-roll processing was successfully performed and will be demonstrated.

The Inkjet printing technology is a direct patterning technique to deposit functional materials with high precision and accuracy. This deposition technology is often used to manufacture conductive electrodes for different active and passive electronic devices on flexible foils. It is an up-scalable process in terms of printing devices from low (via. Sheet-to-Sheet, S2S platform) to high (via. Roll-to-Roll platform) quantities. For manufacturing of these conductive electrodes and hence electronic devices through the R2R platform, a suitable post-treatment/curing methodology is very much desired. In this work, the focus is concentrated on the curing methodology using the Infra-red radiation for both the inkjet-printed conductive electrodes and insulator layer, for completing a ""proof of concept"" Metal-Insulator-Metal (MIM) electronic device structure over the R2R platform. A conductive silver nano-particle and a polymeric dielectric ink are used to print the top and bottom conductive electrodes, with a middle insulator layer for the MIM structure respectively. It is observed that not only the printed silver electrode layers (both top and bottom) can be cured with the help of the Infra-red radiation, but also the insulator layer. Additionally, the layers constituting the MIM device structure is cured with the conventional curing methodology which in this case is thermal curing using a convection oven. This curing procedure for the printed functional layers is generally performed for the S2S manufacturing process. The conductive electrodes are then electrically characterized by measuring the sheet resistance (on the foil and dielectric layer) as a function of the un-conventional Infra-red radiation and conventional oven curing methodologies. The cured layers for both the conductive electrodes and insulator layers are morphologically analyzed for the layer thickness and homogeneity. The electrical performance of the cured insulator in form of the obtained capacitance from the MIM passive device is compared for the two mentioned curing methodologies.