• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 33
  • 32
  • 27
  • 4
  • 3
  • 2
  • 2
  • 2
  • 1
  • 1
  • Tagged with
  • 124
  • 30
  • 25
  • 23
  • 14
  • 13
  • 12
  • 12
  • 12
  • 12
  • 10
  • 9
  • 9
  • 9
  • 9
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Enhanced Detection Strategies Accomplished Through Metal Binding and Miniature Mass Spectrometry

Graichen, Adam 01 February 2013 (has links)
A multiplexed method for performing MS/MS on multiple ions simultaneously in a miniature rectilinear ion trap (RIT) mass spectrometer has been developed. This method uses an ion encoding procedure that relies on the mass bias that exists when ions are externally injected into an RIT operated with only a single phase RF applied to one pair of electrodes. The ion injection profile under such conditions ions is Gaussian-like over a wide range of RF amplitudes, or low mass cutoff (LMCO) values, during ion accumulation. We show that this distribution is related to ion m/z and is likely caused by ions having an optimal range of pseudo-potential well depths for efficient trapping. Based on this observation, precursor ion intensity changes between two different injection LMCO values can be predicted, and these ion intensity changes are found to be carried through to their corresponding product ions, enabling multiplexed MS/MS spectra to be deconvoluted. The gas-phase reactions of a series of coordinatively unsaturated [Ni(L)n]y+ complexes, where L is a nitrogen-containing ligand, with chemical warfare agent (CWA) simulants in a miniature rectilinear ion trap mass spectrometer were investigated as part of a new approach to detect CWA. Results show that the metal complex ions can react with low concentrations of several CWA simulants, including dipropyl sulfide (simulant for mustard gas), acetonitrile (simulant for the nerve agent tabun), and diethyl phosphite (simulant for nerve agents sarin, soman, tabun, and VX), thereby providing a sensitive means of detecting these compounds. The [Ni(L)n]2+ complexes are found to be particularly reactive with the simulants of mustard gas and tabun, allowing their detection at low parts-per-billion (ppb) levels. These detection limits are well below the median lethal doses for these CWAs, which indicates the applicability of this new approach, and are about two orders of magnitude lower than electron ionization detection limits on the same mass spectrometer. The use of coordinatively unsaturated metal complexes as reagent ions offers the possibility of further tuning the ion-molecule chemistry so that desired compounds can be detected selectively or at even lower concentrations. Mass spectrometry has become a tool for studying noncovalently bound complexes. Specifically, electrospray ionization mass spectrometry (ESI-MS) has found increasing use for the determination of affinity (Ka) or dissociation (Kd) constants. Direct measurement of the equilibrium components by ESI-MS is the most straightforward approach for determining binding equilibrium constants, but this approach is prone to error and has some inherent limitations. Transferring complexes from solution to the gas phase may perturb the equilibrium concentrations and/or different ionization efficiencies may cause the resulting ion signals not to reflect actual solution concentrations. Furthermore, ESI only works under a limited range of solvent conditions (i.e. low ionic strengths), which limits the broad applicability of this approach. We propose an approach based on covalent labeling in the context of metal-catalyzed oxidation (MCO) reactions that, when combined with MS, overcomes such limitations when determining metal-ligand binding constants. The MCO-MS approach will provide concurrent information regarding metal binding site and metal-protein binding affinity. Optimization of the MCO reaction through isotopic mass tags will permit enhanced identification of modified residues. Application of this method to study the affinity and binding interactions of other divalent metals with β2m are likely to provide insight into the specificity of copper for causing β2m amyloid formation.
52

Miniaturized Electron Optics based on Self-Assembled Micro Coils

Kern, Felix Lucas 10 November 2022 (has links)
Zahlreiche Geräte, die in den Naturwissenschaen, in der Industrie und im Gesundheitswesen unverzichtbar sind, basieren auf Strahlen schneller geladener Teilchen. Dazu zählen unter anderem Elektronen- und Ionenmikroskope, entsprechende Lithographiestrahlanlagen und Röntgenstrahlungsquellen. Magnetische Optiken, die Strahlen geladener Teilchen ablenken, formen und fokussieren, sind das Rückgrat aller Geräte die mit hochenergetischen Teilchen arbeiten, da sie im Vergleich zu Optiken, die auf elektrischen Feldern basieren, bei hohen Teilchengeschwindigkeiten eine überlegene optische Leistung aufweisen. Konventionelle makroskopische magnetische Optiken sind jedoch groß, teuer und platzraubend, nicht hochfrequenzfähig und erfordern aktive (Wasser-)Kühlung zur Wärmeabfuhr. Sie sind daher für Mehrstrahlinstrumente, miniaturisierte Anwendungen und schnelle Strahlmanipulation ungeeignet, die für zukünftige Fortschritte in der Nanofabrikation und -analyse gebraucht werden. Im Rahmen dieser Arbeit wurden die ersten magnetischen selbst-assemblierenden Mikro-Origami-Elektronenoptiken entwickelt, hergestellt und charakterisiert. Mit dem verwendeten Miniaturisierungsansatz können, bei ähnlicher optischer Leistung, alle oben genannten Nachteile von konventionellen magnetischen Optiken überwunden werden. Die außergewöhnlichen Eigenschaften dieser optischen Elemente werden durch die einzigartigen Merkmale der Mikrospulen ermöglicht: geringe Größe, geringe Induktivität und geringer Widerstand. Im Rahmen dieser Arbeit wurden unter anderem adaptive Phasenplaen hergestellt, die Elektronenvortexstrahlen mit einem bislang unerreichten Bahndrehimpuls von bis zu mehreren 1000 ̄h erzeugen. Des Weiteren wurden schnelle Elektronenstrahldeflektoren zur Strahlablenkung, zum zweidimensionalen Rastern und für stroboskopische Experimente gefertigt. Sie besitzen eine Ablenkleistung im mrad-Bereich für 300 kV Elektronen und einen Frequenzdurchgang bis zu 100 MHz. Darüber hinaus wurden miniaturisierte adrupollinsen mit Brennweiten kleiner als 46 mm für 300 kV Elektronen entwickelt. Diese drei Arten elektronenoptischer Elemente sind von großem Interesse für verschiedenste Anwendungen in der Nanofabrikation und -analyse, da sie unter anderem als integrale Bestandteile von zu entwickelnden Mehrstrahlinstrumenten, miniaturisierten Geräten und stroboskopischen Messaufbauten dienen können.:1 Introduction 1.1 Charged Particle Optics 1.2 Miniaturized Charged Particle Optics 1.3 Phase Plates for Transmission Electron Microscopy 2 Charged Particle Optics 2.1 Hamiltonian Formalism 2.2 Gaussian Matrix Optics 2.3 Transfer Matrices of Magnetic Elements 2.3.1 Single Quadrupole 2.3.2 Quadrupole Multiplets 2.3.2.1 Quadrupole Doublet 2.3.2.2 Quadrupole Triplet 2.3.2.3 Higher Order Quadrupole Multiplets 2.4 Scaling Laws for Charged Particle Optics 2.4.1 Thin Film 2.4.2 Electrostatic Scaling Laws 2.4.3 Magnetic Scaling Laws 3 Design and Fabrication of Miniaturized Electron Optics 3.1 Basics of Polymer-Based Self-Assembly Technology 3.2 Basic Coil Design and Magnetic Field Simulations 3.3 CoFeSiB-Pyrex Core-Shell Micro Wires 3.4 Fabrication of Self-Assembled Micro Coil Devices 4 Optical Properties of Self-Assembled Miniaturized Electron Optics 4.1 Electron Vortex Phase Plate 4.1.1 Projected Magnetic Fields 4.1.2 Vortex Beam Characteristics 4.2 Miniaturized Deflector 4.3 Quadrupole Focusing Optic 4.4 High Frequency Characteristics of Self-Assembled Electron Optics 5 Summary and Outlook 5.1 Applications of Electron Vortex Beams with Large OAM 5.2 Optics of Large Optical Power for Pulsed Instruments 5.3 Stroboscopic TEM Measurements 5.4 Miniaturized Wigglers, Undulators and Free Electron Lasers 5.5 Towards Integrated Electron Optical Systems / Beams of highly accelerated charged particles are essential for numerous indispensable devices used throughout natural sciences, industry and the healthcare sector, e.g., electron and ion microscopes, charged particle lithography machines and X-ray radiation sources. Magnetic charged particle optics that deflect, shape and focus high-energy charged particles are the backbone of all such devices, because of their superior optical power compared to electric field optics at large particle velocities. Conventional macroscopic magnetic optics, however, are large, costly and bulky, not high frequency capable and require active cooling for heat dissipation. They are therefore unsuitable for fast beam manipulation, multibeam instrumentation, and miniaturized applications, much desired for future advances in nanofabrication and analysis. The first on-chip micro-sized magnetic charged particle optics realized via a self-assembling micro-origami process were designed, fabricated and characterized within the frame of this work. The utilized micro-miniaturization approach overcomes all the aforementioned obstacles for conventional magnetic optics, while maintaining similar optical power. The exceptional properties of these optical elements are rendered possible by the unique features of strain-engineered micro-coils: small size, small inductance and small resistivity. Within the frame of this work, adaptive phase plates were fabricated, which generate electron vortex beams with an unprecedented orbital angular momentum of up to several 1000 ̄h. Furthermore, fast electron beam deflectors for beam blanking, two-dimensional scanning and stroboscopic experiments were manufactured. They possess a deflection power in the mrad regime for 300 kV electrons and a high frequency passband up to 100 MHz. Additionally, miniaturized strong quadrupole lenses with focal lengths down to 46 mm for 300 kV electrons have been developed. These three types of electron optical elements are of great interest for a wide range of applications in nanofabrication and analysis, as they serve as integral components of future multibeam instruments, miniaturized devices, and stroboscopic measurement setups to be developed.:1 Introduction 1.1 Charged Particle Optics 1.2 Miniaturized Charged Particle Optics 1.3 Phase Plates for Transmission Electron Microscopy 2 Charged Particle Optics 2.1 Hamiltonian Formalism 2.2 Gaussian Matrix Optics 2.3 Transfer Matrices of Magnetic Elements 2.3.1 Single Quadrupole 2.3.2 Quadrupole Multiplets 2.3.2.1 Quadrupole Doublet 2.3.2.2 Quadrupole Triplet 2.3.2.3 Higher Order Quadrupole Multiplets 2.4 Scaling Laws for Charged Particle Optics 2.4.1 Thin Film 2.4.2 Electrostatic Scaling Laws 2.4.3 Magnetic Scaling Laws 3 Design and Fabrication of Miniaturized Electron Optics 3.1 Basics of Polymer-Based Self-Assembly Technology 3.2 Basic Coil Design and Magnetic Field Simulations 3.3 CoFeSiB-Pyrex Core-Shell Micro Wires 3.4 Fabrication of Self-Assembled Micro Coil Devices 4 Optical Properties of Self-Assembled Miniaturized Electron Optics 4.1 Electron Vortex Phase Plate 4.1.1 Projected Magnetic Fields 4.1.2 Vortex Beam Characteristics 4.2 Miniaturized Deflector 4.3 Quadrupole Focusing Optic 4.4 High Frequency Characteristics of Self-Assembled Electron Optics 5 Summary and Outlook 5.1 Applications of Electron Vortex Beams with Large OAM 5.2 Optics of Large Optical Power for Pulsed Instruments 5.3 Stroboscopic TEM Measurements 5.4 Miniaturized Wigglers, Undulators and Free Electron Lasers 5.5 Towards Integrated Electron Optical Systems
53

Широкополосные и миниатюрные мостовые устройства : магистерская диссертация / Broadband and miniature bridge device

Ларин, А. В., Larin, A. V. January 2014 (has links)
В настоящее время область применения радиоэлектронных средств расширяется, комплексы радиосистем становятся все более сложными, это полностью относится и к радиотехнике СВЧ диапазона. В связи с расширением физических возможностей радиоэлектронной аппаратуры во многих случаях необходимо не только излучать и принимать СВЧ сигнал, но также производить его обработку и преобразование, поэтому усложняются СВЧ схемы и в прежнем исполнении становятся громоздкими, поэтому возникает необходимость создания миниатюрных схем, работающих в СВЧ диапазоне. / Currently, the scope of radio electronic means expands, complexes of radio systems become more complex, it relates to radio engineering microwave range. In connection with the physical capabilities of electronic equipment in many cases, it is necessary not only to emit and receive microwave signals, but also to make its processing and conversion, so more complex microwave circuits in the previous execution is cumbersome, therefore there is the need to create miniature circuits operating in the microwave range.
54

Миниатюризация микрополосковых СВЧ-устройств : магистерская диссертация / Miniaturization mikrobiolosko-o microwave devices

Летавин, Д. А., Letavin, D. A. January 2016 (has links)
Данная работа посвящена миниатюризации квадратурных и кольцевых мостовых устройств. Описана процедура проектирования миниатюрных конструкций, основанная на замене отрезка микрополосковой линии передачи на фильтр нижних частот, обладающий таким же фазовым сдвигом, что и заменяемый отрезок. Проведено моделирование предлагаемых конструкций и получены их частотные характеристики. Изготовлены опытные образцы, и измерены их характеристики, которые подтверждают работоспособность устройства. / This work is dedicated to the miniaturization of the quadrature ring and bridge devices. The procedure of designing miniature structures based on replacement of a segment of microstrip transmission line on a low-pass filter, which has the same phase shift that model and cut. The simulation of the proposed designs and obtained their frequency characteristics. Built prototypes of, and measured their characteristics, which confirm the efficiency of the device.
55

Swiss-Roll Microbattery: Design, Fabrication, and Integration

Li, Yang 04 January 2023 (has links)
Microbatteries are being considered as the critical components for portable and smart microelectronics, including remote sensors, micro-electromechanical systems, microrobots, implantable medical devices, and the Internet of Things, owing to their high energy densities, long life span, and facile on-chip integration. To date, tremendous efforts have been devoted to developing new methodologies for building high-performance microbatteries with minimum footprint areas. However, an effective and reliable fabrication procedure that is compatible with the modern microelectronics industry has not yet been reported for microbatteries so far. Two main issues need to be considered for the device design: (1) pursuing satisfying energy and power densities at limited footprint area is highly desired by constructing the 3D microelectrode architecture with high aspect ratio while reducing its footprint; (2) a novel technology is highly demanded to produce the 3D microstructure following an on-chip processing route which is compatible with the manufacturing procedure of microelectronic devices. Rolled-up nanotechnology can transform a large-area planar precursor into a micrometer-sized Swiss-roll by careful strain-engineering and state-of-the-art micro-patterning techniques with a micro-origami self-assembly process, which reduces the device size for monolithic integration. This dissertation demonstrates brand-new 3D Swiss-roll microbatteries with high performance at a sub-square millimeter-scale by employing rolled-up nanotechnology. Two types of micro-batteries with different configurations have been designed and fabricated, including twin Swiss-roll and single Swiss-roll structures. The twin Swiss-roll microbattery is fabricated based on two separated Swiss-roll micro-scaffolds with a parallel structure and controllable distance between them. The tuneable mesostructure benefits the mass loading of electroactive materials, rendering the excellent energy density at a greatly reduced footprint area. The twin Swiss-roll configuration is conducive to compatibility with novel battery chemistries due to its separated parallel Swiss-roll structure. In order to further decrease the overall footprint area, a single Swiss-roll configuration is designed for a fully integrated Swiss-roll microbattery. Micro-anode and micro-cathode are integrated into a single Swiss-roll configuration with an extremely small footprint area, which benefits the integration and miniaturization of microelectronics. Finally, an integrated device composed of a single Swiss-roll microbattery and UV photodetector is successfully fabricated within 1 mm2. The concept presented here enables the high-performance microbattery that can break through the limitation on microbattery’s footprint area, which opens up the new vision for the future on-chip microelectronics.:Table of contents Chapter 1. Introduction 1 1.1. Background and motivation of this work 1 1.2. Dissertation structure 2 Chapter 2. Overview of 3D microbatteries 5 2.1. Electrochemical energy storage 5 2.2. Rechargeable zinc batteries 6 2.2.1. Alkaline rechargeable zinc batteries 7 2.2.2. Aqueous zinc ion batteries 8 2.2.3. Dual-ion hybrid zinc batteries 9 2.3. Configurations for 3D microbatteries 10 2.3.1. 3D sandwiched architecture 12 2.3.2. 3D interdigital architecture 13 2.3.3. Rolled-up microtubular architecture 15 2.4. Conclusion 17 Chapter 3. Overview of rolled-up technology 21 3.1. Self-rolled-up inorganic layers 21 3.2. Self-rolled-up polymeric shapeable platform 24 3.3. Applications of rolled-up nanomembranes for energy storage devices 26 3.3.1. Rolled-up active materials for LIBs 26 3.3.2. Rolled-up micro-platform for in-situ investigation 27 3.3.3. Rolled-up integratable 3D micro-capacitors/supercapacitors 29 Chapter 4. Experimental methods 35 4.1. Fabrication technologies 35 4.1.1. Photolithography 36 4.1.2. Electron beam evaporation 37 4.1.3. Magnetron sputtering deposition 38 4.1.4. Electrochemical deposition 39 4.2. Characterization methods 40 4.2.1. Scanning electron microscopy, focused ion beam milling, and energy dispersive spectrometry 40 4.2.2. X-ray diffraction 41 4.2.3. Raman spectroscopy 41 4.2.4. Electrochemical characterization 42 4.2.5. Finite element method simulations 43 Chapter 5. A twin Swiss-roll microbattery 45 5.1. Introduction 45 5.2. Fabrication and characterization of twin Swiss-roll microbattery 46 5.2.1. Reshape a 2D precursor to a 3D mesostructured Swiss-roll 46 5.2.2. The construction of Swiss-roll microelectrodes 48 5.3. Results and discussion 51 5.3.1. The encapsulation of twin Swiss-roll microbattery 51 5.3.2. Electrochemical performance of twin Swiss-roll microbattery 52 5.3.3. Practical applications of twin Swiss-roll microbattery 55 5.4. Conclusion 57 Chapter 6. A single Swiss-roll microbattery 59 6.1. Introduction 59 6.2. Fabrication of Swiss-roll Zn-Ag microbattery 60 6.2.1. Fabrication of micro-origami layer stack 61 6.2.2. Fabrication of battery components 63 6.2.3. Self-roll-up of single Swiss-roll microbattery 63 6.3. Results and discussion 65 6.3.1. Materials characterization 65 6.3.2. Electrolyte optimization 65 6.3.3. Electrochemical performance of single Swiss-roll microbattery 70 6.4. Conclusion 73 Chapter 7. Summary and outlook 75 7.1. Summary 75 7.2. Outlook 77 Bibliography 79 List of figures 87 List of tables 91 Versicherung 93 Acknowledgment 95 Publications and presentations 97 Curriculum vita 99
56

Miniaturization of Folded Slot Antennas through Inductive Loading and Thin Film Packaging

Karnick, David A. 15 March 2011 (has links)
No description available.
57

Étude et minimisation du facteur de qualité des antennes pour de petits objets communicants / Study an optimization of the quality factor of small antennas

Diop, Oumy 27 September 2013 (has links)
Actuellement, les objets communicants sans fils occupent une place prépondérante. Pour faciliter leur utilisation, ces objets sont de plus en plus petits et nécessitent de très petites antennes. Cette miniaturisation d’antennes implique forcément une détérioration de leurs performances. La conception d’antennes électriquement petites (AEP) nécessite une très bonne compréhension théorique des mécanismes électromagnétiques mis en jeu notamment quelles limites précises peut-on atteindre pour une AEP étant circonscrive dans un volume donné. Un des paramètres essentiels d’une AEP est son facteur de qualité intrinsèque qui est inversement proportionnel à sa bande passante en impédance. Ainsi, maximiser la bande passante en impédance d’une antenne consiste à minimiser son facteur de qualité. Face à ce problème, de nombreux travaux ont été développés pour déterminer les limites possibles pour des AEP. C’est dans ce cadre que s’inscrit le premier axe de recherche de la thèse : étudier le facteur de qualité d’AEP, afin de déterminer s’il existe des dimensions optimales permettant de s’approcher de ces limites. Le second axe de recherche a consisté à étudier des AEP fonctionnant à 2,45 GHz pour des implants biomédicaux. Celles-ci sont imprimées sur de nouveaux types de substrat pour avoir une meilleure résolution de trace métallique favorisant une réduction de l’encombrement, et une intégration facilitant ainsi les interconnexions avec les frontaux RF. Le challenge consiste à maximiser les performances de ces antennes. Plusieurs prototypes ont été réalisés pour valider les simulations. / Currently, wireless devices play an important role in everyday life. For ease-of-use, these devices are becoming smaller and require very small antennas. However, the size reduction of these antennas necessarily implies a degradation of their performance. Consequently, the design of electrically small antennas (ESA) requires a very good theoretical understanding of the electromagnetic phenomenon that takes place, especially in terms of accurate performance that can be expected for an ESA with given dimensions. An important parameter of an ESA is its intrinsic quality factor since it is inversely proportional to its impedance bandwidth. Indeed, maximizing the matching bandwidth of an antenna consists in minimizing its quality factor. Facing this problem, many researches have been developed to determine the possible limits of the quality factor of ESA. The first research axis of this thesis is to study the quality factor of ESA to determine whether optimal dimensions exist to approach the fundamental quality factor limits. The second part of the thesis studies miniature antennas for biomedical implants operating at 2.45 GHz. These antennas are printed on a specific microelectronic substrate to ensure a better resolution in terms of metallic traces in order to reduce the size and allow easier integration to facilitate interconnections with RF front-end. The challenge consists in maximizing the performance of these antennas. The presented results are supported by means of electromagnetic models and simulations on one hand. Also, several prototypes are fabricated to validate these simulations.
58

Vers l'intégration de fonctions d'imagerie sur le plan focal infrarouge Application à la conception et à la réalisation d'une caméra sur puce infrarouge cryogénique / Towards the integration of optical functions on the infrared focal plane array Application to the design and manufacture of an infrared cryogenic on-chip camera

De la Barrière, Florence 05 October 2012 (has links)
La miniaturisation des systèmes optiques est un domaine de recherche qui suscite un grand intérêt scientifique actuellement. En effet, moins volumineux et moins chers, ils peuvent prétendre à être diffusés dans des applications diverses. L'objectif de cette thèse est de concevoir des systèmes d'imagerie extrêmement compacts, intégrés au plus près du détecteur infrarouge refroidi, et idéalement solidaires de celui-ci. Des travaux de recherche sont actuellement menés pour miniaturiser les systèmes optiques : moins volumineux et moins chers, ils peuvent prétendre à être diffusés dans des applications diverses. L'objectif de cette thèse est de concevoir des systèmes d'imagerie extrêmement compacts, intégrés au plus près du détecteur infrarouge refroidi, et idéalement solidaires de celui-ci. J'ai tout d'abord mis en évidence des stratégies pour la simplification et la miniaturisation des systèmes optiques. Parmi elles, les approches menant à des systèmes multivoies semblent être les plus prometteuses pour concevoir des systèmes à la fois compacts et performants. J'ai alors proposé deux architectures multivoies simples, compactes et intégrées au plus près du détecteur infrarouge. La première, de champ d'observation égal à 120°, intègre une matrice de microlentilles à quelques centaines de micromètres seulement du détecteur infrarouge : elle est qualifiée de caméra sur puce. Des défis technologiques ont dû être relevés pour réaliser ce composant. J'ai développé un algorithme de reconstruction d'images et évalué expérimentalement les performances de la caméra. Ce système produit, après traitements, une image échantillonnée au pas de 7,5 µm. Cette valeur est deux fois meilleure que celle qui pourrait être obtenue avec une caméra monovoie classique, associée à un détecteur infrarouge à l'état de l'art actuel, avec un pas pixel de 15 µm. J'ai contribué à la réalisation du second système en développant une méthode originale et simple pour en fabriquer les matrices de microlentilles. Cette technique consiste à mouler par compression de la poudre de bromure de potassium à température ambiante.Ces travaux ouvrent la voie à une nouvelle génération de détecteurs infrarouges, qui intègrent une fonction d'imagerie. / Miniaturizing optical systems is a research area of great interest nowadays: if they were smaller and cheaper, optical systems could be widespread in many applications. This work aims at designing very compact optical systems for imagery applications, which could be integrated near the infrared cryogenic detector and ideally directly on it.First, I have presented original design strategies to simplify and miniaturize optical systems. Approaches which lead to multichannel systems seem to be the most interesting ones to design compact and effective systems. Then, I have proposed two multichannel optical architectures, which are simple, compact, and integrated near the infrared detector. The first camera, which has a field of view equal to 120°, integrates a microlens array at a few hundreds of micrometers only of the infrared detector: it is called a wafer-level camera. Technological challenges have been overcome to manufacture this component. I have developed an image processing method, and assessed the characteristics of the camera experimentally. This system samples the final image with a pitch equal to 7,5 µm. This value is two times better than the one which could be obtained by using a one-channel camera associated with a state-of-the-art infrared detector, with a pixel pitch equal to 15 µm. In order to manufacture the second architecture, I have developed an original and simple method to obtain the microlens arrays, by compression molding of Potassium Bromide powder at ambient temperature. This work gives some elements to design a new generation of infrared detectors with an imagery function.
59

Magneto-Dielectric Polymer Nanocomposite Engineered Substrate for RF and Microwave Antennas

Morales, Cesar A. 01 January 2011 (has links)
This dissertation presents the first reported systematic investigation on the implementation of multilayer patch antennas over Fe3O4-based polymer nanocomposite (PNC) magneto-dielectric substrates. The PNC substrate is created by the monodispersion of Fe3O4 nanopthesiss, with mean size of 7.5nm, in a polymeric matrix of Polydimethylsiloxane (PDMS). Recently, magneto-dielectric substrates have been proposed by several researchers as a means for decreasing the size and increasing the bandwidth of planar antennas. Nevertheless, factors such as high loss and diminished control over magnetic and dielectric properties have hindered the optimal performance of antennas. In addition, the incompatibility and elevated complexity prevents integration of conventional magnetic materials with antennas and standard fabrication processes at printed circuit boards (PCBs) and wafer levels. Additionally, the low hysteresis losses exhibited by uniformly embedded superparamagnetic nanopthesiss complemented by the ease of integration of polymer nanocomposites in standard fabrication processes, offer promising solutions to resolve any of the complications and concerns foresaid. Towards this dissertation work, one multilayer antenna was constructed over a molded PDMS substrate along with three similar antennas built on PDMS-Fe3O4 PNC substrates with different Fe3O4 nanopthesis loading concentrations in the PDMS matrix of 80%, 50% and 30% by weight. This pioneering work in the experimental implementation and characterization of magneto-dielectric PNC antennas has not only resulted in antennas with different operational frequencies in the 3-5GHz band, but also expanded our knowledge base by correlating the concentration of magnetic nanopthesiss to key antenna performance metrics such as antenna bandwidth, antenna efficiency and miniaturization factors. Among the most significant results a magneto-dielectric antenna with maximum miniaturization factor of 57%, and a 58% increase in bandwidth, whilst retaining an acceptable antenna gain of 2.12dBi, was successfully demonstrated through the deployment of molded PDMS-Fe3O4 PNC substrate under external DC bias magnetic fields. This dissertation also presents a versatile process for constructing flexible and multilayer antennas by the seamless incorporation of a variety of materials such as PDMS, Liquid Crystal Polymer (LCP) laminates, metal clads and molded magneto-dielectric polymer nanocomposites with evenly embedded magnetic nanopthesiss.
60

Microwell devices for single-cell analyses

Lindström, Sara January 2009 (has links)
Powerful tools for detailed cellular studies are emerging, increasing the knowledge ofthe ultimate target of all drugs: the living cell. Today, cells are commonly analyzed inensembles, i.e. thousands of cells per sample, yielding results on the average responseof the cells. However, cellular heterogeneity implies the importance of studying howindividual cells respond, one by one, in order to learn more about drug targeting andcellular behavior. In vitro assays offering low volume sampling and rapid analysis in ahigh-throughput manner are of great interest in a wide range of single-cellapplications. This work presents a microwell device in silicon and glass, developed using standardmicrofabrication techniques. The chip was designed to allow flow-cytometric cellsorting, a controlled way of analyzing and sorting individual cells for dynamic cultureand clone formation, previously shown in larger multiwell plates only. Dependent onthe application, minor modifications to the original device were made resulting in agroup of microwell devices suitable for various applications. Leukemic cancer cellswere analyzed with regard to their clonogenic properties and a method forinvestigation of drug response of critical importance to predict long-term clinicaloutcome, is presented. Stem cells from human and mouse were maintainedpluripotent in a screening assay, also shown useful in studies on neural differentiation.For integrated liquid handling, a fluidic system was integrated onto the chip fordirected and controlled addition of reagents in various cell-based assays. The chip wasproduced in a slide format and used as an imaging tool for low-volume sampling withthe ability to run many samples in parallel, demonstrated in a protein-binding assay fora novel bispecific affinity protein. Moving from cells and proteins into geneticanalysis, a method for screening genes from clones in a rapid manner was shown bygene amplification and mutation analysis in individual wells. In summary, a microwelldevice with associated methods were developed and applied in a range of biologicalinvestigations, particularly interesting from a cell-heterogeneity perspective. / QC 20100728

Page generated in 0.0238 seconds