60 research outputs found

    Liquid cooled micro-scale gradient system for magnetic resonance

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    Schaltbare magnetische Feldgradientspulen sind ein geeignetes Werkzeug fĂŒr die Modulation der KernspinprĂ€zession in der gepulsten Kernspinresonanzspektroskopie und Bildgebung. Die Magnetresonanztomographie von mikroskopischen Proben benötigt starke, schnell schaltbare Magnetfeldgradienten, um diffusionsbedingte Artefakte zu unterdrĂŒcken, SuszeptibilitĂ€tseffekte abzuschwĂ€chen und um die Messzeit zu verkĂŒrzen. Verschiedene Techniken können eingesetzt werden, um eine hohe GradientenintensitĂ€t zu erreichen, wie zum Beispiel die Erhöhung der StromstĂ€rke oder die Steigerung der Windungsdichte der Feldspule. Ein weiterer, geeigneter technischer Ansatz besteht darin, die Gradientenspulen nĂ€her an der Probe zu platzieren. Als Konsequenz wird aber die durch die Joule-ErwĂ€rmung verursachte WĂ€rmeentwicklung zu einem zentralen Problem. In dieser Arbeit wird ein neuartiges Design, ein Mikroherstellungsprozess und eine Kernspin-Evaluierung eines Feldgradientenchips prĂ€sentiert. Die Gradientenspulen wurden besonders hoch miniaturisiert und durch den Einsatz von verbesserten und neuartigen Strukturierungsverfahren entwickelt. Zuerst wird ein Fertigungsverfahren zur Herstellung einer kompakten Hochfrequenzspule vorgestellt. Durch den Einsatz einer maskenlosen RĂŒckseitenlithographie konnte die ProzesskomplexitĂ€t reduziert werden. Dieses Verfahren wurde durch Tintenstrahldruck mit Nanopartikeln realisiert, wobei die gedruckten Strukturen selbst als lithographische Maske fĂŒr die Herstellung einer galvanischen Form dienen. Somit werden die SeitenwĂ€nde der galvanischen Form durch die gedruckte Seed-Schicht optimal selbst ausgerichtet. Dies ermöglichte eine anisotrope Galvanisierung, um eine höhere elektrische LeitfĂ€higkeit der gedruckten Leiterbahnen zu erzielen. Aus den Erkenntnissen der ausgearbeiteten Herstellungsprozesse wurde ein optimiertes Spulendesign fĂŒr ein-axiale sowie drei-axiale linearen Gradientenchips entwickelt. Die einachsige lineare zz-Gradientenspule wurde mit der Stream-Function-Methode berechnet, wobei die Optimierung darauf abgestimmt wurde, eine minimale Verlustleistung zu erzielen. Die Gradientenspulen wurden auf zwei Doppellagen implementiert, die mittels Cu-Galvanik in Kombination mit fotodefinierbaren Trockenfilm-Laminaten aufgebracht wurden. Bei dem hier vorgestellten Herstellungsverfahren diente die erste Metallisierungschicht gleichzeitig dazu, Widerstands-Temperaturdetektoren zu integrieren. Um niederohmige Spulen zu realisieren wurde der Galvanisierungsprozess soweit angepasst, um eine hohe Schichtdicke zu erzielen. Die Chipstruktur beinhaltet ein aktives KĂŒhlsystem, um dem Aufheizen der Spulen entgegenzuwirken. Thermographische Aufnahmen in Kombination mit den eingebetteten Temperatursensoren ermöglichen es, die Erhitzung der Spule zu analysieren, um die Strombelastbarkeit zu ermitteln. Die Gradientenspule wurde mit einer Hochfrequenz-Mikrospule in einer Flip-Chip-Konfiguration zusammengebaut, und mit diesem Aufbau wurde ein eindimensionales Kernspinexperiment durchgefĂŒhrt. Es wurde eine Gradienteneffizienz von 3.15 T m−1 A−1T\,m^{−1}\,A^{−1} bei einer ProfillĂ€nge von 1.2 mmmm erreicht

    Advances in Micro and Nano Manufacturing: Process Modeling and Applications

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    Micro- and nanomanufacturing technologies have been researched and developed in the industrial environment with the goal of supporting product miniaturization and the integration of new functionalities. The technological development of new materials and processing methods needs to be supported by predictive models which can simulate the interactions between materials, process states, and product properties. In comparison with the conventional manufacturing scale, micro- and nanoscale technologies require the study of different mechanical, thermal, and fluid dynamics, phenomena which need to be assessed and modeled.This Special Issue is dedicated to advances in the modeling of micro- and nanomanufacturing processes. The development of new models, validation of state-of-the-art modeling strategies, and approaches to material model calibration are presented. The goal is to provide state-of-the-art examples of the use of modeling and simulation in micro- and nanomanufacturing processes, promoting the diffusion and development of these technologies

    Metal Micro-forming

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    The miniaturization of industrial products is a global trend. Metal forming technology is not only suitable for mass production and excellent in productivity and cost reduction, but it is also a key processing method that is essential for products that utilize advantage of the mechanical and functional properties of metals. However, it is not easy to realize the processing even if the conventional metal forming technology is directly scaled down. This is because the characteristics of materials, processing methods, die and tools, etc., vary greatly with miniaturization. In metal micro forming technology, the size effect of major issues for micro forming have also been clarified academically. New processing methods for metal micro forming have also been developed by introducing new special processing techniques, and it is a new wave of innovation toward high precision, high degree of processing, and high flexibility. To date, several special issues and books have been published on micro-forming technology. This book contains 11 of the latest research results on metal micro forming technology. The editor believes that it will be very useful for understanding the state-of-the-art of metal micro forming technology and for understanding future trends

    Development of self-cleaning polymeric surfaces using polymer processing systems for application to high-voltage insulators

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    Herein, polymer processing systems are used to fabricate superhydrophobic high-temperature vulcanized (HTV) silicone rubber surfaces by direct replication. HTV silicone rubber is one of the main polymeric housing materials used in high-voltage insulators. The selected polymer processing techniques are compression molding and injection molding.The direct replication approach requires that a template or insert having the desired surface patterns be replicated onto a target polymer surface via a polymer processing. The appropriate micro-nanostructures, required for achieving ultra-water-repellency, were created on the insert materials (an aluminum alloy) using a wet-chemical etching method. As a flawless demolding is essential to acquire desirable replication quality, an antistiction coating was applied to the insert surfaces prior to the molding process to ensure the thorough removal of the silicone rubber during the demolding. The resulting silicone rubber surfaces possessed micro-nanostructures producing a water contact angle (WCA) of >160° and a contact angle hysteresis (CAH) of <3°. The surface roughness of the aluminum inserts was optimized at HCl concentrations of 15 wt.%. The self-cleaning properties of the produced ultra-water-repellent silicone rubber surfaces were rigorously investigated to ensure a self-cleaning surface at real outdoor imitated conditions. The presence of air pockets in between the surface asperities produced the Cassie-Baxter regime. The consistency of these air pockets is crucial for attaining the self-cleaning properties. A series of tests, including droplet impact, water-jet impact, trapped air layer, and severe droplet contact tests were conducted to confirm the stability of the Cassie-Baxter regime. A comprehensive series of self-cleaning experiments involving both suspended and non-suspended contaminants, e.g., kaolin, carbon black, and silica as well as contaminant-applying methods, e.g., dropwise, spraying, wet or dry contamination were performed. Self-cleaning tests were organized from less severe, i.e., non-suspended contamination tests, to severe, i.e., the wet suspended contamination test, to most severe, i.e., the dry suspended contamination test. Due to their ultra-low CAH, the produced surfaces demonstrated favorable self-cleaning properties against the various types of contaminants and the different means of contaminant application. The produced surfaces retained their water repellency following the application of the contaminants and successful cleaning of the surfaces, thereby verifying the self-cleaning performance and resistance of the fabricated superhydrophobic silicone rubber surfaces. The anti-icing properties (delayed ice formation) and de-icing properties (reduced ice adhesion strength) of the produced surfaces were evaluated. Two types of icing (atmospheric glaze and bulk ice) were considered to accumulate ice on the surfaces. The well-known ice adhesion measurement techniques, i.e., the centrifuge adhesion and push-off tests were employed to provide quantitative comparisons of the ice adhesion strength of the produced surfaces. The produced surfaces significantly delayed ice formation and reduced the ice adhesion strength. To rigorously assess the durability of the produced surfaces, a comprehensive series of experiments that covered a wide range of real-life conditions were carried out. In some cases, where the water repellency was lost, the silicone rubber surfaces demonstrated a satisfactory recovery of their anti-wetting properties. Given the importance of replication quality in the direct replication of micro-nanostructures and the role of micro-nanostructures in the formation of superhydrophobic and icephobic surfaces, the effect of processing parameters on the superhydrophobicity, icephobicity, and replication quality in the compression molding of silicone rubber surfaces were evaluated. Curing time, mold temperature, molding pressure, and part thickness were assessed via response surface methodology to determine the optimal processing parameters. Molding pressure and part thickness were revealed as two main influencing parameters in the superhydrophobic properties. The crosslink density of the fabricated silicone rubber samples, however, was found to be significantly affected by curing time and mold temperature. Replication quality was determined for various molding pressures and part thicknesses. There was an optimal molding pressure value at each part thickness level to obtain the best replication quality. Surfaces having the highest replication quality showed the longest freezing delay reflecting their potential use as anti-icing surfaces. Although all superhydrophobic surfaces offered potential icephobic properties, identifying the influential parameters controlling ice adhesion was more complicated. As this PhD project is part of an industrial-academic collaboration, the results obtained in the laboratory experiments were used for implementation in the industry (K-Line Insulators Limited). This step includes the use of aluminum and stainless-steel inserts. Using the injection molding system available at K-Line Insulators Ltd., silicone rubber insulators having superhydrophobic properties were produced successfully. The industrial partner provided facilities to modify its mold to produce superhydrophobic insulators in an industrial scale. Dans cette thĂšse, les systĂšmes de transformation des polymĂšres sont utilisĂ©s pour fabriquer des surfaces superhydrophobes de caoutchouc de silicone vulcanisĂ© Ă  haute tempĂ©rature (HTV) Ă  partir d’une rĂ©plication directe. Le HTV est l’un des principaux matĂ©riaux polymĂšres utilisĂ©s dans la fabrication des isolateurs Ă  haute tension. Les systĂšmes considĂ©rĂ©s sont des procĂ©dĂ©s de moulage par compression et de moulage par injection. L'approche de rĂ©plication directe nĂ©cessite un modĂšle ou un insert ayant les structures de surface souhaitĂ©e Ă  rĂ©pliquer sur la surface du polymĂšre. Les micronanostructures appropriĂ©es pour obtenir la non-mouillabilitĂ© de la surface ont Ă©tĂ© crĂ©Ă©es sur les matĂ©riaux d'insert (alliage d'aluminium) en utilisant un procĂ©dĂ© de gravure chimique. Comme un dĂ©moulage sans dĂ©faut est essentiel pour obtenir la qualitĂ© de rĂ©plication souhaitable, un revĂȘtement antiadhĂ©sif est appliquĂ© sur les surfaces de l'insert avant le processus de moulage afin d’assurer l'Ă©limination complĂšte du caoutchouc de silicone lors du dĂ©moulage. Les surfaces de caoutchouc de silicone dĂ©veloppĂ©es possĂ©daient des micronanostructures produisant un angle de contact eau (WCA) de > 160 ° et une hystĂ©rĂ©sis angle de contact (CAH) de < 3 °. La rugositĂ© optimale de surface des inserts en aluminium est obtenue Ă  une concentration massique de HCl de 15%. Les propriĂ©tĂ©s autonettoyantes des surfaces produites ont Ă©tĂ© rigoureusement Ă©tudiĂ©es pour assurer que ces propriĂ©tĂ©s autonettoyantes demeuraient efficaces dans des conditions extĂ©rieures rĂ©elles. La prĂ©sence de poches d'air entre les aspĂ©ritĂ©s de surface est responsable de la formation du rĂ©gime de Cassie-Baxter. La consistance de ces poches d’air est cruciale pour obtenir des propriĂ©tĂ©s autonettoyantes. Par consĂ©quent, une sĂ©rie d’essais ont Ă©tĂ© effectuĂ©s pour confirmer la stabilitĂ© du rĂ©gime Cassie-Baxter. Ensuite, une sĂ©rie complĂšte d'expĂ©riences de propriĂ©tĂ©s autonettoyantes a Ă©tĂ© rĂ©alisĂ©e en impliquant des contaminants en suspension et non suspendus (non dispersĂ©s) utilisant divers matĂ©riaux (par exemple, le kaolin, le noir de carbone, la silice, etc.) et des mĂ©thodes d'application de contaminants (par exemple, goutte Ă  goutte, pulvĂ©risation, contaminants humides ou secs) ont Ă©tĂ© effectuĂ©es. Les tests d’autonettoyage ont Ă©tĂ© organisĂ©s, du test le moins sĂ©vĂšre, c’est-Ă -dire de la contamination non suspendue (non dispersĂ©e), au test plus sĂ©vĂšre, c’est-Ă -dire de la contamination en suspension humide, et se terminant par le test le plus sĂ©vĂšre, Ă  savoir la contamination en suspension sĂšche. En raison du CAH ultra-bas, les surfaces produites ont montrĂ© des propriĂ©tĂ©s autonettoyantes favorables contre les diffĂ©rents types de contaminants et de diffĂ©rents moyens d'application de contaminants. Les surfaces produites ont conservĂ© leurs propriĂ©tĂ©s rĂ©pulsives aprĂšs l'application des contaminants et aprĂšs le nettoyage des surfaces, permettant ainsi de vĂ©rifier les performances d'autonettoyage et la rĂ©sistance des surfaces en silicone superhydrophobe fabriquĂ©es. Les propriĂ©tĂ©s anti-givrantes (la formation retardĂ©e de la glace) et les propriĂ©tĂ©s glaciophobes (la force d'adhĂ©rence rĂ©duite de la glace) des surfaces produites ont Ă©tĂ© Ă©valuĂ©es. Les surfaces produites sont exposĂ©es Ă  la formation de deux types de givrage. Les techniques bien connues de mesure de l'adhĂ©sion sur la glace, Ă  savoir le test d'adhĂ©rence par centrifugation et le test de poussĂ©e, ont Ă©tĂ© utilisĂ©es pour obtenir une comparaison prĂ©cise des rĂ©sultats. Les surfaces superhydrophobes produites ont considĂ©rablement retardĂ© la formation de glace et rĂ©duit la force d'adhĂ©rence de la glace. Afin d’évaluer de maniĂšre rigoureuse les propriĂ©tĂ©s de durabilitĂ©, une sĂ©rie complĂšte d’expĂ©riences a Ă©tĂ© rĂ©alisĂ©e sur les surfaces. Les expĂ©riences de durabilitĂ© ont Ă©tĂ© menĂ©es pour couvrir un large Ă©ventail d'applications rĂ©elles. En ce qui concerne la capacitĂ© attractive du caoutchouc de silicone dans la rĂ©cupĂ©ration des propriĂ©tĂ©s anti-mouillantes, la perte de la propriĂ©tĂ© de rĂ©pulsion de l’eau a Ă©tĂ© rĂ©gĂ©nĂ©rĂ©e jusqu’à un niveau satisfaisant dans certains cas. Compte tenu de l’importance de la qualitĂ© de la rĂ©plication dans la rĂ©plication directe des micronanostructures d’une part, et d’autre part du rĂŽle des micronanostructures dans la formation de surfaces superhydrophobes et glaciophobes, les effets des paramĂštres de moulage par compression des surfaces en caoutchouc de silicone sur la superhydrophobicitĂ©, la glaciophobicitĂ© et la qualitĂ© de la rĂ©plication ont Ă©tĂ© Ă©valuĂ©es. Le temps de durcissement, la tempĂ©rature de moulage, la pression de moulage et l'Ă©paisseur de la piĂšce ont Ă©tĂ© choisis comme paramĂštres de traitement Ă  Ă©valuer. La mĂ©thodologie de surface de rĂ©ponse a Ă©tĂ© utilisĂ©e pour dĂ©terminer les paramĂštres de traitement optimaux. BĂ©nĂ©ficiant des rĂ©sultats, la pression et l'Ă©paisseur ont Ă©tĂ© rĂ©vĂ©lĂ©es comme les deux paramĂštres d'influence principaux des propriĂ©tĂ©s superhydrophobes. La densitĂ© de rĂ©ticulation des Ă©chantillons de caoutchouc de silicone fabriquĂ©s s'est toutefois rĂ©vĂ©lĂ©e ĂȘtre significativement affectĂ©e par le temps et la tempĂ©rature. Les valeurs de qualitĂ© de rĂ©plication ont Ă©tĂ© dĂ©terminĂ©es en fonction de diverses pressions et Ă©paisseurs. Il y avait une valeur de pression optimale Ă  chaque niveau d'Ă©paisseur pour obtenir la meilleure qualitĂ© de rĂ©plication. Il a Ă©galement Ă©tĂ© observĂ© que les surfaces prĂ©sentant la meilleure qualitĂ© de rĂ©plication affichaient le plus long retard de gel de la gouttelette d’eau, ce qui reprĂ©sentait leur potentiel Ă©levĂ© d'utilisation en tant que surfaces antigivrantes. Bien que toutes les surfaces superhydrophobes aient prĂ©sentĂ© des propriĂ©tĂ©s potentiellement glaciophobes, il a Ă©tĂ© constatĂ© que le scĂ©nario d’adhĂ©rence sur la glace Ă©tait plus compliquĂ© en termes de paramĂštres influents. Ce projet de doctorat fait partie d'une collaboration industrielle-acadĂ©mique. Les rĂ©sultats obtenus en laboratoire ont Ă©tĂ© utilisĂ©s pour la mise en Ɠuvre dans l'industrie (K-Line Insulators Limited). À cette Ă©tape, des inserts en aluminium et en acier inoxydable ont Ă©tĂ© utilisĂ©s. En utilisant le systĂšme de moulage par injection disponible chez K-Line Insulators Ltd., des isolateurs en caoutchouc de silicone ayant des propriĂ©tĂ©s superhydrophobes ont Ă©tĂ© produits avec succĂšs. Par consĂ©quent, le partenaire industriel fournit des installations pour modifier son moule afin de produire des isolateurs superhydrophobes Ă  l'Ă©chelle industrielle

    IN-SITU ADDITIVE MANUFACTURING OF METALS FOR EMBEDDING PARTS COMPATIBLE WITH LIQUID METALS TO ENHANCE THERMAL PERFORMANCE OF AVIONICS FOR SPACECRAFT

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    With advances in micromachinery, the aggregation of sensors, and more powerful microcontroller platforms on satellites, the size of avionics for space missions are getting dramatically smaller with faster processing speeds. This has resulted in greater localized heat generation, requiring more reliable thermal management systems to enhance the thermal performance of the avionics. The emergence of advanced additive manufacturing (AM), such as selective laser melting (SLM) and engineering materials, such as low-melting eutectic liquid metal (LM) alloys and synthetics ceramics offer new opportunities for thermal cooling systems. Therefore, there has been an opportunity for adapting in-situ AM to overcome limitations of traditional manufacturing in thermal application, where improvements can be achieved through reducing thermal contract resistance of multi-layer interfaces. This dissertation investigates adapting in-situ AM technologies to embed LM compatible prefabricated components, such as ceramic tubes, inside of metals without the need for a parting surface, resulting in more intimate contact between the metal and ceramic and a reduction in the interfacial thermal resistance. A focus was placed on using more ubiquitous powder bed AM technologies, where it was determined that the morphology of the prefabricated LM compatible ceramic tubes had to be optimized to prevent collision with the apparatus of powder bed based AM. Furthermore, to enhance the wettability of the ceramic tubes during laser fusion, the surfaces were electroplated, resulting in a 1.72X improvement in heat transfer compared to cold plates packaged by conventional assembly. Additionally, multiple AM technologies synergistically complement with cross platform tools such as magnetohydrodynamic (MHD) to solve the corrosion problem in the use of low melting eutectic alloy in geometrically complex patterns as an active cooling system with no moving parts. The MHD pumping system was designed using FEA and CFD simulations to approximate Maxwell and Navier-Stokes equations, were then validated using experiments with model heat exchanger to determine the tradeoff in performance with conventional pumping systems. The MHD cooling prototype was shown to reach volumetric flow rates of up to 650 mm3/sec and generated flow pressure due to Lorentz forces of up to 230 Pa, resulting in heat transfer improvement relative to passive prototype of 1.054

    BioMEMS

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    As technological advancements widen the scope of applications for biomicroelectromechanical systems (BioMEMS or biomicrosystems), the field continues to have an impact on many aspects of life science operations and functionalities. Because BioMEMS research and development require the input of experts who use different technical languages and come from varying disciplines and backgrounds, scientists and students can avoid potential difficulties in communication and understanding only if they possess a skill set and understanding that enables them to work at the interface of engineering and biosciences. Keeping this duality in mind throughout, BioMEMS: Science and Engineering Perspectives supports and expedites the multidisciplinary learning involved in the development of biomicrosystems. Divided into nine chapters, it starts with a balanced introduction of biological, engineering, application, and commercialization aspects of the field. With a focus on molecules of biological interest, the book explores the building blocks of cells and viruses, as well as molecules that form the self-assembled monolayers (SAMs), linkers, and hydrogels used for making different surfaces biocompatible through functionalization. The book also discusses: Different materials and platforms used to develop biomicrosystems Various biological entities and pathogens (in ascending order of complexity) The multidisciplinary aspects of engineering bioactive surfaces Engineering perspectives, including methods of manufacturing bioactive surfaces and devices Microfluidics modeling and experimentation Device level implementation of BioMEMS concepts for different applications. Because BioMEMS is an application-driven field, the book also highlights the concepts of lab-on-a-chip (LOC) and micro total analysis system (ÎŒTAS), along with their pertinence to the emerging point-of-care (POC) and point-of-need (PON) applications

    Micro/Nano Manufacturing

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    Micro manufacturing involves dealing with the fabrication of structures in the size range of 0.1 to 1000 ”m. The scope of nano manufacturing extends the size range of manufactured features to even smaller length scales—below 100 nm. A strict borderline between micro and nano manufacturing can hardly be drawn, such that both domains are treated as complementary and mutually beneficial within a closely interconnected scientific community. Both micro and nano manufacturing can be considered as important enablers for high-end products. This Special Issue of Applied Sciences is dedicated to recent advances in research and development within the field of micro and nano manufacturing. The included papers report recent findings and advances in manufacturing technologies for producing products with micro and nano scale features and structures as well as applications underpinned by the advances in these technologies

    3D-nanostrukturierte Multielektrodenarrays : Konzeption, Prozessentwicklung und Untersuchung des Einflusses maßgeschneiderter Nanostrukturen auf elektrochemische Eigenschaften, ZelladhĂ€sion und Signalableitung

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    Um das Verhalten von Zellen auf interne oder externe Stimuli zu analysieren, können die von den Zellen abgegebenen Signale mittels sogenannter Multielektrodenarrays (MEAs) detektiert werden. Dreidimensionale Nanostrukturen auf den ElektrodenoberflĂ€chen des MEAs können dabei zu einer Verbesserung der Zell-Elektroden-Kopplung beitragen und vergrĂ¶ĂŸern darĂŒber hinaus die elektrochemisch aktive OberflĂ€che, was zu einer Erhöhung des Signal-Rausch-VerhĂ€ltnisses wĂ€hrend der Messung fĂŒhrt. Unterschiedliche Zelltypen verhalten sich bezĂŒglich ihrer AdhĂ€sionscharakteristiken sehr variabel und benötigen deshalb individuell auf sie abgestimmte Nanostrukturdimensionen und -anordnungen. Daher wurde im Rahmen dieser Dissertation eine Prozesslinie zur Fertigung 3D-nanostrukturierter MEA-Chips erarbeitet, die die Herstellung verschiedener MEA-Chips mit unterschiedlichen Nanostrukturlayouts erlaubt. Die ElektrodenoberflĂ€chen wurden mittels Rasterkraft- und Rasterelektronenmikroskopie sowie elektrochemischer Methoden untersucht. Beim Vergleich charakteristischer elektrochemischer Werte konnte abhĂ€ngig vom Design eine signifikante Verbesserung auf Seiten der nanostrukturierten Elektroden festgestellt werden. WĂ€hrend der zellbiologischen Versuchsreihen fĂŒhrten im Besonderen ĂŒberwachsene Röhrenstrukturen mit einem Durchmesser von 600 nm und einem Strukturabstand von 5 ”m zu einer deutlichen Steigerung der Zell-Elektroden-AdhĂ€sion und der gemessenen Signalamplituden.Analyzing the cell behavior upon internal or external stimuli, cell signals can be detected by so called multielectrode arrays (MEAs). Three-dimensional nanostructures on top of the electrodesÂŽ surfaces of the MEAs can lead to an improvement of the cell-electrode coupling and enlarge the electrochemical active surface area, thus leading to a crucial increase of the signal-to-noise ratio during the measurement. Obviously, different cells act very variable regarding their adhesion behavior. Therefore, each individual cell type might need specific dimensions and a certain arrangement of nanostructures. In this work, a process line of 3D nanostructured MEA chips is presented which allows the fabrication of a whole set of MEA chips with different nanostructure layouts in one single approach. The surfaces of the electrodes are characterized by using atomic force and scanning electron microscopy as well as electrochemical methods. By comparing characteristic electrochemical values a design-dependent improvement of the nanostructured electrodes could be revealed. Especially, overgrown tube structures with a diameter of 600 nm and a distance of 5 ”m showed good characteristics during the cell-biological experiments, resulting in a distinct increase of the cell-electrode adhesion and an improvement of the recorded signal amplitudes

    High-precision micro-machining of glass for mass-personalization

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    With the fourth industrial revolution manufacturing industry faces new challenges. Small batches of personalized parts, where the geometry changes per part, must be produced in an economically viable manner. In such cases of mass personalization new manufacturing technologies are required which can keep manufacturing overhead related to change of part geometries low. These processes need to address the issues of extensive calibration and tooling costs, must be able to handle complex parts and reduce production steps. According to recent studies hybrid technologies, including electrochemical technologies, are promising to address these manufacturing challenges. At the same time, glass has fascinated and attracted much interest from both the academic and industrial world, mainly because it is optically and radio frequency transparent, chemically inert, environmentally friendly and it has excellent mechanical and thermal properties, allowing tailoring of new and dedicated applications. However, glass is a hard to machine material, due to its hardness and brittleness. Machining smooth, high-aspect ratio structures is still challenging due to long machining times, high machining costs and poor surface quality. Hybrid methods like Spark Assisted Chemical Engraving (SACE) perform well to address these issues. Nevertheless, SACE cannot be deployed for high-precision glass mass-personalization by industry and academia, due to 1) lack of process models for glass cutting and milling, relating SACE input parameters to a desired output, 2) extensive calibration needed for tool-workpiece alignment and tool run-out elimination, 3) part specific tooling required for proper clamping of the glass workpiece to attain high precision. In this study, SACE technology was progressively developed from a mass-fabrication technology towards a process for mass-personalization of high-precision glass parts by addressing these issues. Key was the development of 1) an (empirically validated) model for SACE cutting and milling process operations allowing direct relation of the machining input to the desired machining outcome, enabling a dramatical increase of automation across the manufacturing process workflow from desired design to establishing of machinable code containing all necessary manufacturing execution information, 2) in-situ fabrication of the needed tooling and 3) the use of low-cost rapid prototyping, eliminating high indirect machining costs and long lead times. To show the viability of this approach two novel applications in the microtechnology field were proposed and developed using glass as substrate material and SACE technology for rapid prototyping: a) fabrication of glass imprint templates for microfabricating devices by hot embossing and b) manufacturing of glass dies for micro-forming of metal micro parts

    Integrated 3D glass modules with high-Q inductors and thermal dissipation for RF front-end applications

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    The objectives of this research are to model, design, fabricate and validate high quality factor (Q > 100 at 2.4 GHz for 3-10 nH/mm2) inductors and innovative thermal structures with copper through-package vias to maintain low junction temperatures of < 85 oC in power amplifiers, and demonstrate ultra-thin fully-integrated dual-band (2.4 GHz/ 5GHz) WLAN modules with passive-active integration on ultra-thin glass substrates with double-side RF circuits and copper through-package vias (TPVs). Today’s RF subsystems are 2D single or multichip packages made of either organic laminates or LTCC (low temperature co-fired ceramic) substrates. The need for form-factor reduction in RF subsystems in both z and x-y direction has led to the evolution of embedded die-package architectures in thin laminates with dies facing up or down. This also reduces insertion loss and improves signal integrity by minimizing electromagnetic interference (EMI), package parasitics and routing issues. For further improvement in performance and miniaturization, glass is proposed as an ideal substrate for RF module integration. However, major design and fabrication challenges need to be addressed to achieve ultra-thin high Q RF components and also enable IC cooling to eliminate hotspots on glass substrates, which forms the key focus of this thesis.Ph.D
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