Exziton-Polaritonen sind hybride Quasiteilchen, die entstehen durch die starke Kopplung zwischen Halbleiter-Exzitonen und Mikrokavitätsphotonen in einem optischen Resonator. Aufgrund ihres bosonischen Charakters können die Polaritonen Kondensate ausbilden. In dieser Arbeit ist der emittierende organische Halbleiter das fluoreszierende Protein mCherry. Um einen räumlichen Einschluss zu generieren wurden hemisphärische Potentiale genutzt. Durch die Variation der Potentiallandschaft (Linse, Molekül, Kette, Su-Schrieffer-Heeger-Kette und Honigwaben-Gitter) konnten Eigenschaften wie beispielsweise topologisch nicht-triviale Defekte experimentell bei Umgebungstemperatur demonstriert werden. Zusammengefasst beschäftigt sich diese Arbeit mit der Exziton-Polartion Kondensation in unterschiedlichen Potentiallandschaften mit dem organischen Halbleiter mCherry. / Exciton polaritons are hybrid quasiparticles that are created by the strong coupling between semiconductor excitons and microcavity photons in an optical cavity. Due to their bosonic character, the polaritons can form condensates. In this work, the emitting organic semiconductor is the fluorescent protein mCherry. Hemispherical potentials were used to create a spatial confinement. By varying the potential landscape (lens, molecule, chain, Su-Schrieffer-Heeger chain and honeycomb lattice), properties such as topological non-trivial defects were experimentally demonstrated at ambient temperature. In conclusion, this work deals with exciton-polarisation condensation in different potential landscapes with the organic semiconductor mCherry.

The purpose of this report was to investigate how an intake for a battery-powered leaf blowershould be designed to reduce sound emissions. A reduced sound emission improves both theworking environment for the user but also reduces disturbances to the surroundings. The workbegan with a market analysis of different leaf blowers’ intakes. Other industries and differenttypes of noise reduction systems were also investigated. The market analysis stated that animplementation of Helmholtz resonators in an intake has great potential to reduce the tonalsound that a battery-powered leaf blower emits. As the sound image of a battery-powered leafblower is very tonal, the idea with resonators was to reduce the tonal spikes to achieve a lowersound level. If the work could prove that the resonators provide a high effect in the area aroundthe tonal sound spikes, then with some optimization, the resonators could be adapted and lowerthe sound equally at these frequencies. The work then progressed with testing whetherresonators work effectively. The result of the test showed that resonators can dampenfrequencies with high power, which led to the work continuing with a Concept Generation. The concept generation resulted in four different concepts that all had different placements andimplementations of resonators in the intake. These concepts were tested again and comparedto a reference that did not have any sound dampening features. From this test, two conceptsperformed at a high level, which were Back Cone and Big and Large, and these were furtherdeveloped. Further development produced four different variants of Big and Large. These werevariants with different numbers of resonators. Back Cone was produced in three differentvariants with different sizes of resonators. The purpose of these variants was to investigate howthe size and number of resonators affect the sound dampening ability. These variants weretested according to ISO-22868:2021. The final test revealed that four prototypes achieve therequired value for sound minimization. However, several external parameters emerged that affected the test results. One parameter was likely a floor reflex between the leaf blower and themicrophone directly behind the intake. The influence of the external parameters leads to thecredibility of the test results being unclear and thus these prototypes cannot be approved. During the same test, a speaker was used as the sound source instead of the fan. In this test, itappears the same four prototypes achieve a sound-minimizing effect that achieves the requiredeffect in the same range as in the tests with a fan as a sound source. Even in this test, there wereseveral external parameters that affected the result and therefore the prototypes could not beapproved with certainty according to the requirements specification. The project can be summed up by stating that resonators have great potential to reduce thetonal sound that a battery-powered leaf blower generates. The project has also shown howdifferent placements of resonators affect the sound dampening effect. During test two, a prototype emerged that can be approved according to the requirement specification as itperformed 17,5 dB maximum sound dampening effect right above the tonal frequency and sixdB at the right frequency. The project cannot determine with certainty if the variants of intakeused in the final tests meet the requirement specification due to the external parameters thataffected the results. However, the project can state that the resonators have achieved an effectin all tests. The maximum effect achieved was analysed in test one and was 27 dB soundminimization. The project ends by proposing further work such as investigating how an intakewith resonators should be designed to be manufactured in mass production. The influence ofthe thickness of the intakes surface boundary layer on the effect of the resonator should also beexamined, as well as the distance of the resonator to the fan and the outer edge of the intakeshould be examined together with the several other points presented in the chapter Discussions.

Thesis (PhD (Physics))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: There are many applications where a Gaussian laser beam is not ideal, for example, in areas such as medicine, data storage, science, manufacturing and so on, and yet in the vast majority of laser systems this is the fundamental output mode. Clearly this is a limitation, and is often overcome by adapting the application in mind to the available beam. A more desirable approach would be to create a laser beam as the output that is tailored for the application in mind – so called intra-cavity laser beam shaping. The main goal of intra-cavity beam shaping is the designing of laser cavities so that one can produce beams directly as the output of the cavity with the required phase and intensity distribution. Shaping the beam inside the cavity is more desirable than reshaping outside the cavity due to the introduction of additional external losses and adjustment problems. More elements are required outside the cavity which leads to additional costs and larger physical systems. In this thesis we present new methods for phase and amplitude intra– cavity beam shaping. To illustrate the methods we give both an analytical and numerical analysis of different resonator systems which are able to produce customised phase and intensity distributions. In the introduction of this thesis, a detailed overview of the key concepts of optical resonators is presented. In Chapter 2 we consider the well–known integral iteration algorithm for intra–cavity field simulation, namely the Fox–Li algorithm and a new method (matrix method), which is based on the Fox–Li algorithm and can decrease the computation time of both the Fox–Li algorithm and any integral iteration algorithms. The method can be used for any class of integral iteration algorithms which has the same calculation integrals, with changing integrants. The given method appreciably decreases the computation time of these algorithms and approaches that of a single iteration. In Chapter 3 a new approach to modeling the spatial intensity profile from Porro prism resonators is proposed based on rotating loss screens to mimic the apex losses of the prisms. A numerical model based on this approach is presented which correctly predicts the output transverse field distribution found experimentally from such resonators. In Chapter 4 we present a combination of both amplitude and phase shaping inside a cavity, namely the deployment of a suitable amplitude filter at the Fourier plane of a conventional resonator configuration with only spherical curvature optical elements, for the generation of Bessel–Gauss beams as the output. In Chapter 5 we present the analytical and numerical analyses of two new resonator systems for generating flat–top–like beams. Both approaches lead to closed form expressions for the required cavity optics, but differ substantially in the design technique, with the first based on reverse propagation of a flattened Gaussian beam, and the second a metamorphosis of a Gaussian into a flat–top beam. We show that both have good convergence properties, and result in the desired stable mode. In Chapter 6 we outline a resonator design that allows for the selection of a Gaussian mode by diffractive optical elements. This is made possible by the metamorphosis of a Gaussian beam into a flat–top beam during propagation from one end of the resonator to the other. By placing the gain medium at the flat–top beam end, it is possible to extract high energy in a low–loss cavity. / AFRIKAANSE OPSOMMING: Daar is verskeie toepassings waar ʼn Gaussiese laser bundel nie ideaal is nie, in gebiede soos mediese veld, stoor van data, vervaardiging en so meer, en tog word die meeste laser sisteme in die fundamentele mode bedryf. Dit is duidelik ’n beperking, en word meestal oorkom deur aanpassing van die toepassing tot die beskikbare bundel. ’n Beter benadering sou wees om ʼn laser bundel te maak wat afgestem is op die toepassing - sogenaamde intra-resonator bundel vorming. Die hoofdoel van intra-resonator bundel vorming is om resonators te ontwerp wat direk as uitset kan lewer wat die gewenste fase en intensiteits-distribusie vertoon. Vorming van die bundel in die resonator is voordeliger omdat die vorming buite die resonator tot addisionele verliese asook verstellings probleme bydra. Meer elemente word benodig buite die resonator wat bydra tot hoër koste en groter sisteme. In hierdie tesis word nuwe fase en amplitude intra-resonator bundelvormings metodes voorgestel. Om hierdie metode te demonstreer word analitiese en numeriese analises vir verskillende resonator sisteme wat aangepaste fase en intensiteit distribusies produseer, bespreek. In die inleiding van die tesis word ʼn detailleer oorsig oor die sleutel konsepte van optiese resonators voorgelê. In hoofstuk 2 word die bekende integraal iterasie algoritme vir intraresonator veld simulasie, naamlik die Fox-Li algoritme, en ʼn nuwe metode (matriks metode), wat gebaseer is op die Fox-Li algoritme, en die berekeningstyd van beide die Fox-Li algoritme en enige ander integraal iterasie algoritme verminder. Die metode kan gebruik word om enige klas van integraal iterasie algoritmes wat dieselfde berekenings integrale het, met veranderde integrante (waar die integrand die veld van die lig golf is in die geval van die Fox-Li algoritme, IFTA, en die skerm metode. Die voorgestelde metode verminder die berekeningstyd aansienlik, en is benaderd die van ʼn enkel iterasie berekening. In hoofstuk 3 word ʼn nuwe benadering om die modellering van die ruimtelike intensiteitsprofiel van Porro prisma resonators, gebaseer op roterende verliese skerms om die apeks-verliese van die prismas te benader, voorgestel. ʼn Numeriese model gebaseer op hierdie benadering wat die uitset van die transversale veld distribusie in eksperimentele resonators korrek voorspel, word voorgestel. In hoofstuk 4 word ʼn tegniek vir die generering van Bessel-Gauss bundels deur die gebruik van ʼn kombinasie van amplitude en fase vorming in die resonator en ʼn geskikte amplitude filter in die Fourier vlak van ʼn konvensionele resonator konfigurasie met optiese elemente wat slegs sferiese krommings het, voorgestel. In hoofstuk 5 word die analitiese en numeriese analises van twee nuwe resonator sisteme vir die generering van sogenaamde “flat–top” bundels voorgestel. Beide benaderings lei na ʼn geslote vorm uitdrukking vir die resonator optika wat benodig word, maar verskil noemenswaardig in die ontwerptegniek. Die eerste is baseer op die terug voortplanting van plat Gaussiese bundel, en die tweede op metamorfose van Gaussiese “flat-top” bundel. Ons toon aan dat beide tegnieke goeie konvergensie het, en in die gevraagde stabiele modus lewer. In hoofstuk 6 skets ons die resonator ontwerp wat die selektering van ʼn Gaussiese modus deur diffraktiewe optiese element moontlik maak. Dit word moontlik deur die metamorfose van ’n Gaussiese bundel na ʼn “flat-top” gedurende die voortplanting van die een kant van die resonator na die ander. Deur die wins medium aan die “flat–top” kant van die bundel te plaas word dit moontlik om hoë energie te onttrek in ʼn lae verlies resonator.

Union between top-down and bottom-up assembly is inevitable when scaling down physical, chemical, and biological sensors and probes. Current sensor/probe-based technologies are firmly founded on top-down manufacturing, with limitations in cost of production, manufacturing methods, and material constraints. As an alternative to such limitations, contemporary synthesis techniques for one-dimensional nanostructures have been combined with established methods of micro-fabrication for the development of novel tools and techniques for nanotechnology. More specifically, this dissertation is a systematic study of the synthesis and characterization of ZnO nanostructures for piezoelectric applications. Within this study the following goals have been achieved: 1) rational design and control of a diversity of novel ZnO nanostructures, 2) improved understanding of polar-surface-dominated (PSD) phenomena among Wurtzite crystal structures, 3) confirmation of Taskers Rule via the synthesis, characterization, and modeling of polar-surface-dominated nanostructures, 4) measurement of the surface-charge density for real polar surfaces of ZnO, 5) confirmation of the electrostatic polar-charge model used to describe polar-surface-dominated phenomena, 6) dispersion of ZnO nanobelts onto the selective layers of surface acoustic wave (SAW) devices for gas sensing applications, 7) manipulation of ZnO nanostructures using an atomic force microscope (AFM) for the development of piezoelectric devices, 8) fabrication of bulk acoustic resonator (BAR) and film bulk acoustic resonator (FBAR) devices based on the integrity of individual ZnO belts, 9) electrical characterization of a ZnO belt BAR device, 10) prediction and confirmation of the electrical response from a BAR device using a one-dimensional Krimholt-Leedom-Matthaei (KLM) model, and 11) development of a finite element model (FEM) to accurately predict the electrical response from ZnO belt BAR and FBAR devices in 3D.

The objective of this thesis research is to develop microelectronic acoustic technology towards biosensor applications. The development of a simple and robust resonator that employs simple microelectronic fabrication techniques for its construction could provide the foundation for a cost-effective sensor platform. Subsequent development of an appropriate surface chemistry treatment would functionalize the resonator as a biosensor. Implementation of this design in an array configuration allows for the development of ligand microarrays, which subsequently allows for multi-ligand recognition signatures as well as testing redundancy. The applications for such a tool extend to a myriad of applications, but the focus of this research is to develop this technology towards an early cancer detection capability. Specifically, I develop a solidly-mounted resonator with thin-film ZnO as my active piezoelectric layer. These resonators undergo an extensive development process to arrive at a final device design and are fully characterized throughout by X-ray diffraction and scattering analysis. Employing silane chemistry, these resonators are functionalized as immunosensors by covalently binding antibodies to the surface of the device. The quality of the surface chemistry is fully assessed using water contact angle, atomic force microscopy and confocal laser scanning microscopy. Functionalized biosensors are then used to quantify the concentration of known proteins marker in both a purified medium and a physiologically-relevant medium.

Ces travaux de thèe portent sur le développement d’un outil d’analyse numérique dédié à l’ étude de nouveaux résonateursà quartz à ondes de volume et utilisant les éléments finis. Cette méthode de caractérisation permet la détermination deséléments du schéma électrique équivalent (résistance, inductance et capacité) d’une fréquence de résonance donnée ainsique son facteur de qualité, tout en prenant en compte dans le modèle la sensibilité du cristal de quartz à la températureet aux contraintes induites par le montage. Une étape de validation est d’abord réalisée afin de vérifier nos choix, enterme de modélisation et de calcul, en confrontant les données issues de la simulation aux mesures de résonateurs déjàexistants. Les trois dispositifs analysés (40 MHz, 10 MHz et 100 MHz) montrent une bonne concordance entre théorieet expérience. Pour obtenir de tels résultats, la structure de maintien est prise en compte et modélisée sous forme dezones d’amortissement de Rayleigh lorsque le piégeage de l’énergie n’est pas optimal (présence d’un mode de plaque).Un aspect important des résonateurs est ensuite étudié : le comportement en température. En effet, les contraintes dedilatation thermique ainsi que l’évolution des coefficients élastiques en fonction de la température induisent une dérivefréquentielle. La comparaison entre théorie et expérience nous permet de vérifier l’allure des courbes et de quantifier ledegré de précision du modèle. L’effet d’une contrainte mécanique appliquée sur le pourtour de la lame de quartz est parla suite introduit dans le modèle en utilisant la méthode de perturbation de Sinha-Tiersten. Il est alors possible de définirl’impact des défauts de fabrication sur la fréquence du résonateur. Enfin, la méthode numérique est appliquée à l’étudede structures innovantes dans le cadre du projet FREQUENCE2009. Il s’agit de revisiter le concept du résonateur BVA etd’envisager des procédés de fabrication collective. L’idée consiste ainsi à remplacer le rayon de courbure d’un résonateur,dont la fréquence utile se trouve aux alentours de 9 MHz, par une série de marches, plus compatible avec les procédés dela micro électronique (DRIE : Deep Reactive Ion Etching). Bien que les résultats expérimentaux soient, dans ce cas, loin denos attentes, nous constatons que l’outil d’analyse est parfaitement capable de prédire les caractéristiques de nouvellesstructures. / This work is devoted to the development of a digital analysis tool dedicated to study new bulk acoustic waves quartz resonatorsby using finite elements. This method of characterization allows the calculation of the elements of the equivalentelectrical circuit (resistor, inductance and capacitor) of a given resonant frequency as well as the quality factor, while takinginto account its sensitivity to the temperature and to the stresses induced by the mounting support. Firstly, a validationphase is carried out in order to check our choices, in terms of modeling and computation, by comparing simulation data tothe measures of existing resonators. The three analyzed devices (40MHz, 10 MHz and 100 MHz) show good agreementbetween theory and experiment. To obtain such results, the mounting support is taken into account and modeled thanks toRayleigh damping areas when the trapping of energy is not optimal (presence of a spurious shell vibration mode). Then, animportant aspect of resonators is studied : the temperature behavior of its vibrating modes. Indeed, the thermal expansionstresses as well as the change of stiffness coefficients according to the temperature induce frequency shift. The comparisonbetween theory and experiment allows us to check the shape of curves and to quantify the accuracy of the model.Thereafter, the effect of mechanical stress applied on the edge of the blank of quartz is introduced in the model by usingthe perturbation method developed by Tiersten and Sinha. So, it is possible to define the influence of some manufacturingdefects on the resonant frequency. Finally, the digital method is applied to study innovative structures in the framework ofthe project FREQUENCE2009. The aim is to review the concept of BVA resonator and consider collective manufacturingprocesses. The idea involves replacing the radius of curvature of a resonator, for which the expected frequency is around9 MHz, by several steps, more compatible with microelectronics processes (DRIE : Deep Reactive Ion Etching). Althoughthe results are far from our expectations, we note that the analysis tool is perfectly able to anticipate the characteristics ofnew structures.

In der vorliegenden Promotion werden zwei ausgewählte Iridate mit Elektronen-Spin-Resonanz untersucht. Bei der ersten Probe handelt es sich um das Doppelperowskit Ba2YIrO6, das nach simpler theoretischer Auffassung kein paramagnetisches Signal besitzen sollte. Allerdings zeigen unterschiedliche magnetische Messungen schwache magnetische Spinkorrelationen. Mit Hilfe von ESR kann die Ursache dieser Signale paramagnetischen Verunreinigungen zugeschrieben werden. Zudem kann der Ursprung dieser Defekte mit zwei unterschiedlichen Oxidationsstufen des Iridiums assoziiert werden.    Bei der zweiten untersuchten Iridat-Probe La2CuIrO6 handelt es sich ebenfalls um ein Material mit Doppelperowskit-Struktur, allerdings interagieren hier zwei grundlegend verschiedene Spinsorten miteinander. Zum einen der sich aus der starken Spin-Bahn-Kopplung ergebende Jeff=1/2 Pseudospin des Iridats und zum anderen der reine S=1/2 Spin des Kupferions. Innerhalb der Kristallstruktur ergibt sich daraus eine komplexe antiferromagnetische Spinstruktur mit einer kleinen Verkippung der Spins. Diese nicht-kollineare Spinanordnung geht auf die Dzyaloshinskii-Moriya-Wechselwirkung zurück und führt letztendlich zu einem kleinen ferromagnetischen Nettomoment. Mit ESR konnte dabei vor allem die temperaturabhängige Wechselwirkung der einzelnen Untergitter gezielt untersucht werden. Zusätzlich zum experimentellen Teil war eine der Kernaufgaben dieser Arbeit die technische Realisierung eines Fabry-Perot Resonators. Ziel des Resonators ist dabei die Erhöhung des Signal/Rauschverhältnisses sowie die Implementierung die Probe innerhalb der Messapparatur zu rotieren. Um ein besseres Verständnis des zugrundeliegenden Resonanzverhaltens zu erhalten, wurden zudem einige Simulationen zum Verhalten der elektromagnetischen Wellen innerhalb des Resonators durchgeführt.

Small and affordable CO2 sensors are in high demand for modern applications, such as smart buildings, smartphones, electrical cars or medicine. The thin-film bulk acoustic resonator (FBAR) presents a promising platform to fulfil these demands by functionalising its surface with materials that reversibly interact with CO2. In this thesis, aminopolysiloxane-coated FBARs are prepared and analysed regarding their CO2-sensing performance. It is found that they can reach high CO2 sensitivity with resolutions up to 50 ppm in a dynamic range between 400 ppm and 5000 ppm. It is also shown that common cross-sensitivities, such as changing humidity, can be separated from the CO2 signal. These are promising results on the way to develop a new generation of CO2 sensors. However, it is also found that the sensor sensitivity decreases over time. Analytical examinations show that the main degradation product in aminopolysiloxanes is urea, which forms preferrably in softer polymers and at temperatures above 80 °C. This degradation is found in all analysed compositions of aminopolysiloxanes that were aged for more than one year showing the stability limitations of this sensor concept.:1 Introduction 9 1.1 Motivation for new CO2 sensors . . . . . . . . . . . . . . . . . . . . . . . . . . 9 1.2 The FBAR as a high-potential sensor device . . . . . . . . . . . . . . . . . . . 10 1.3 Content of this work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2 Fundamentals 13 2.1 Gas Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.1.1 De_nition, History and Classi_cation . . . . . . . . . . . . . . . . . . . 13 2.1.2 Gas sensor characteristics . . . . . . . . . . . . . . . . . . . . . . . . . 15 2.1.3 State-of-the-art CO2 sensors . . . . . . . . . . . . . . . . . . . . . . . . 16 2.2 FBAR Fundamentals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 2.2.1 Acoustic resonator theory . . . . . . . . . . . . . . . . . . . . . . . . . 20 2.2.2 The Mason Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 2.2.3 Sensing theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 2.2.4 Film resonance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 2.3 CO2-sensitive materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 2.3.1 General Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 2.3.2 Classes of CO2 sorbents . . . . . . . . . . . . . . . . . . . . . . . . . . 29 2.3.3 Suitabe materials for the functionalisation of the FBAR . . . . . . . . 35 3 Experimental details 37 3.1 FBAR designs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 3.1.1 Passive FBARs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 3.1.2 Active FBARs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 3.2 Gas measurement setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 3.2.1 Passive FBARs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 3.2.2 Active FBARs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 3.3 Development of the sensitive layer . . . . . . . . . . . . . . . . . . . . . . . . 40 3.3.1 Material choice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 3.3.2 Material preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 3.3.3 Deposition methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 3.3.4 Annealing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 3.4 Analytical techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 3.4.1 Fourier-transform infrared spectroscopy . . . . . . . . . . . . . . . . . 46 3.4.2 Raman spectroscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 3.4.3 X-ray photoelectron spectroscopy . . . . . . . . . . . . . . . . . . . . . 47 3.4.4 Nuclear magnetic resonance spectroscopy . . . . . . . . . . . . . . . . 47 3.4.5 Acoustic measurements . . . . . . . . . . . . . . . . . . . . . . . . . . 47 4 Results and discussion 49 4.1 FBARs functionalised with ethyl cellulose . . . . . . . . . . . . . . . . . . . . 49 4.1.1 Acoustic characterisation . . . . . . . . . . . . . . . . . . . . . . . . . 49 4.1.2 Humidity sensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 4.1.3 Stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 6 Contents 4.2 FBARs with aminopolysiloxanes . . . . . . . . . . . . . . . . . . . . . . . . . 59 4.2.1 Acoustic characterisation . . . . . . . . . . . . . . . . . . . . . . . . . 59 4.2.2 Humidity and CO2 sensing . . . . . . . . . . . . . . . . . . . . . . . . 63 4.2.3 Stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 4.3 Degradation mechanisms in aminopolysiloxanes . . . . . . . . . . . . . . . . . 69 4.3.1 Stability evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 4.3.2 Analytical characterisation . . . . . . . . . . . . . . . . . . . . . . . . 70 4.3.3 Degradation hypothesis . . . . . . . . . . . . . . . . . . . . . . . . . . 78 4.4 CO2 sensing with an active FBAR array . . . . . . . . . . . . . . . . . . . . . 82 4.4.1 Presentation of the functionalised sensor chip . . . . . . . . . . . . . . 82 4.4.2 Sensor characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 4.4.3 Selective Multigassensing . . . . . . . . . . . . . . . . . . . . . . . . . 89 5 Summary 93 6 Outlook 95 7 Appendix 97 7.1 Additional tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 7.2 Additional pictures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 Bibliography 103

Artificial magnetic materials (AMMs) are a type of metamaterials which are engineered to exhibit desirable magnetic properties not found in nature. AMMs are realized by embedding electrically small metallic resonators aligned in parallel planes in a host dielectric medium. In the presence of a magnetic field, an electric current is induced on the inclusions leading to the emergence of an enhanced magnetic response inside the medium at the resonance frequency of the inclusions. AMMs with negative permeability are used to develop single negative, or double negative metamaterials. AMMs with enhanced positive permeability are used to provide magneto-dielectric materials at microwave or optical frequencies where the natural magnetic materials fail to work efficiently. Artificial magnetic materials have proliferating applications in microwave and optical frequency region. Such applications include inversely refracting the light beam, invisibility cloaking, ultra miniaturizing and frequency bandwidth enhancing low profile antennas, planar superlensing, super-sensitive sensing, decoupling proximal high profile antennas, and enhancing solar cells efficiency, among others. AMMs have unique enabling features that allow for these important applications. Fundamental limitations on the performance of artificial magnetic materials have been derived. The first limitation which depends on the generic model of permeability functions expresses that the frequency dispersion in an AMM is limited by the desired operational bandwidth. The other constraints are derived based on the geometrical limitations of inclusions. These limitations are calculated based on a circuit model. Therefore, a formulation for permeability and magnetic susceptibility of the media based on a circuit model is developed. The formulation is in terms of a geometrical parameter that represents the geometrical characteristics of the inclusions such as area, perimeter and curvature, and a physical parameter that represents the physical, structural and fabrication characteristics of the medium. The effect of the newly introduced parameters on the effective permeability of the medium and the magnetic loss tangent are studied. In addition, the constraints and relations are used to methodically design artificial magnetic material meeting specific operational requirements. A novel design methodology based on an introduced analytical formulation for artificial magnetic material with desired properties is implemented. The synthesis methodology is performed in an iterative four-step algorithm. In the first step, the feasibility of the design is tested to meet the fundamental constraints. In consecutive steps, the geometrical and physical factors which are attributed to the area and perimeter of the inclusion are synthesized and calculated. An updated range of the inclusion's area and perimeter is obtained through consecutive iterations. Finally, the outcome of the iterative procedure is checked for geometrical realizability. The strategy behind the design methodology is generic and can be applied to any adopted circuit based model for AMMs. Several generic geometries are introduced to realize any combination of geometrically realizable area and perimeter (s,l) pairs. A realizable geometry is referred to a contour that satisfies Dido's inequality. The generic geometries introduced here can be used to fabricate feasible AMMs. The novel generic geometries not only can be used to enhance magnetic properties, but also they can be configured to provide specific permeability with desired dispersion function over a certain frequency bandwidth with a maximum magnetic loss tangent. The proposed generic geometries are parametric contours with uncorrelated perimeter and area function. Geometries are configured by tuning parameters in order to possess specified perimeter and surface area. The produced contour is considered as the inclusion's shape. The inclusions are accordingly termed Rose curve resonators (RCRs), Corrugated rectangular resonators (CRRs) and Sine oval resonators (SORs). Moreover, the detailed characteristics of the RCR are studied. The RCRs are used as complementary resonators in design of the ground plane in a microstrip stop-band filter, and as the substrate in design of a miniaturized patch antenna. The performance of new designs is compared with the counterpart devices, and the advantages are discussed.

Artificial magnetic materials (AMMs) are a type of metamaterials which are engineered to exhibit desirable magnetic properties not found in nature. AMMs are realized by embedding electrically small metallic resonators aligned in parallel planes in a host dielectric medium. In the presence of a magnetic field, an electric current is induced on the inclusions leading to the emergence of an enhanced magnetic response inside the medium at the resonance frequency of the inclusions. AMMs with negative permeability are used to develop single negative, or double negative metamaterials. AMMs with enhanced positive permeability are used to provide magneto-dielectric materials at microwave or optical frequencies where the natural magnetic materials fail to work efficiently. Artificial magnetic materials have proliferating applications in microwave and optical frequency region. Such applications include inversely refracting the light beam, invisibility cloaking, ultra miniaturizing and frequency bandwidth enhancing low profile antennas, planar superlensing, super-sensitive sensing, decoupling proximal high profile antennas, and enhancing solar cells efficiency, among others. AMMs have unique enabling features that allow for these important applications. Fundamental limitations on the performance of artificial magnetic materials have been derived. The first limitation which depends on the generic model of permeability functions expresses that the frequency dispersion in an AMM is limited by the desired operational bandwidth. The other constraints are derived based on the geometrical limitations of inclusions. These limitations are calculated based on a circuit model. Therefore, a formulation for permeability and magnetic susceptibility of the media based on a circuit model is developed. The formulation is in terms of a geometrical parameter that represents the geometrical characteristics of the inclusions such as area, perimeter and curvature, and a physical parameter that represents the physical, structural and fabrication characteristics of the medium. The effect of the newly introduced parameters on the effective permeability of the medium and the magnetic loss tangent are studied. In addition, the constraints and relations are used to methodically design artificial magnetic material meeting specific operational requirements. A novel design methodology based on an introduced analytical formulation for artificial magnetic material with desired properties is implemented. The synthesis methodology is performed in an iterative four-step algorithm. In the first step, the feasibility of the design is tested to meet the fundamental constraints. In consecutive steps, the geometrical and physical factors which are attributed to the area and perimeter of the inclusion are synthesized and calculated. An updated range of the inclusion's area and perimeter is obtained through consecutive iterations. Finally, the outcome of the iterative procedure is checked for geometrical realizability. The strategy behind the design methodology is generic and can be applied to any adopted circuit based model for AMMs. Several generic geometries are introduced to realize any combination of geometrically realizable area and perimeter (s,l) pairs. A realizable geometry is referred to a contour that satisfies Dido's inequality. The generic geometries introduced here can be used to fabricate feasible AMMs. The novel generic geometries not only can be used to enhance magnetic properties, but also they can be configured to provide specific permeability with desired dispersion function over a certain frequency bandwidth with a maximum magnetic loss tangent. The proposed generic geometries are parametric contours with uncorrelated perimeter and area function. Geometries are configured by tuning parameters in order to possess specified perimeter and surface area. The produced contour is considered as the inclusion's shape. The inclusions are accordingly termed Rose curve resonators (RCRs), Corrugated rectangular resonators (CRRs) and Sine oval resonators (SORs). Moreover, the detailed characteristics of the RCR are studied. The RCRs are used as complementary resonators in design of the ground plane in a microstrip stop-band filter, and as the substrate in design of a miniaturized patch antenna. The performance of new designs is compared with the counterpart devices, and the advantages are discussed.