Dans le contexte d’une population vieillissante il est primordial de développer des outils de diagnostic cliniques précis, fiables, peu coûteux et faciles à mettre en place. Durant cette thèse j’ai en particulier cherché à réaliser une cartographie dynamique des vaisseaux sanguins dans le but de permettre de détecter à la fois des cancers et des maladies cardiovasculaires, deux des maladies les plus mortelles. Pour avoir un diagnostic efficace on se doit d’imager en profondeur avec une résolution spatiale et temporelle la meilleure possible. Dans le chapitre 0 j’explique les enjeux de l’imagerie médicale sur la micro-vascularisation en analysant les avantages et inconvénients de plusieurs types d’imageries médicales. Dans le chapitre 1 je développe en détail l’imagerie photo-acoustique, qui s’est avérée être la plus appropriée à notre application. Elle a l’avantage d’avoir un contraste optique et une résolution acoustique. J’utilise en particulier la photo-acoustique fréquentielle qui est peu onéreuse et peu encombrante, donc facilement intégrable dans le monde hospitalier par rapport à une imagerie photo-acoustique « classique ». Je valide cette partie sur des résultats expérimentaux in-vivo sur des oreilles de souris. Dans le chapitre 2 j’ai cherché à détecter le signal photo-acoustique de façon optique qui a pour avantage d’être sans contact donc sans souci d’encombrement entre « excitation optique » et « détection acoustique ». Je développe le traitement du signal nécessaire pour détecter une onde acoustique, i.e. des vibrations, à l’aide d’un interféromètre. Puis je présente dans le chapitre 3 un interféromètre particulier développé au laboratoire : le Laser Optical Feedback Imaging (LOFI). Il permet de s’affranchir du bruit du détecteur donc il permet de détecter des vibrations de petites amplitudes même sur des surfaces peu réfléchissantes comme la peau et cela même à faible puissance par respect des normes médicales. Dans le chapitre 4 je valide la détection du signal photo-acoustique avec notre détection optique. Enfin dans le chapitre 5 je montre à travers des simulations une technique d’imagerie innovante plein champ qui permettrait de détecter plus rapidement un signal photo-acoustique riche spectralement. / In the context of an aging population, it is essential to develop clinical diagnostic tools that are accurate, reliable, inexpensive and easy to implement. During this thesis I particularly sought to perform a dynamic mapping of blood vessels in order to detect both cancers and cardiovascular diseases, two of the most deadly diseases. In order to have an effective diagnosis, it is necessary to image in depth with the best possible spatial and temporal resolution. In chapter 0 I explain the challenges of medical imaging on micro-vascularization by analyzing the advantages and disadvantages of several types of medical imaging. In chapter 1 I develop in detail the photo-acoustic imaging, which proved to be the most appropriate for our application. It has the advantage of optical contrast and acoustic resolution. In particular, I use frequency photo-acoustics, which is inexpensive and space-saving, and can therefore be easily integrated in the hospital world compared to "traditional" photo-acoustic imaging. I validate this part on in-vivo experimental results on mouse ears. In chapter 2 I tried to detect the photo-acoustic signal in an optical way which has the advantage of being contactless and therefore without any problem of clutter between "optical excitation" and "acoustic detection". I develop the signal processing necessary to detect an acoustic wave, i.e. vibrations, using an interferometer. Then I present in chapter 3 a particular interferometer developed in the laboratory: the Laser Optical Feedback Imaging (LOFI). This interferometer allows to be limited to photon noise even with a low intensity thus it makes it possible to detect vibrations of small amplitudes even on surfaces with a low reflecting index like the skin in accordance with medical standards. In chapter 4 I validate the detection of the photo-acoustic signal with our optical detection. Finally in chapter 5 I show with simulations an innovative full field imaging technique that would allow faster detection of a spectrally rich photo-acoustic signal.

The on-line condition monitoring of turbomachinery blades is of utmost importance to ensure the long term health and availability of such machines and as such has been an area of study since the late 1960s. As a result a number of on-line blade vibration measurement techniques are available, each with its own associated advantages and shortcomings. In general, on-blade sensor measurement techniques suffer from sensor lifespan, whereas non-contact techniques usually have measurement bandwidth limitations. One non-contact measurement technique that yields improvements in the area of measurement bandwidth is laser Doppler vibrometry. This thesis presents results and findings from utilizing laser Doppler vibrometry in an Eulerian fashion (i.e. a fixed reference frame) to measure on-line blade vibrations in axial-flow turbomachinery. With this measurement approach, the laser beam is focussed at a fixed point in space and measurements are available for the periods during which each blade sweeps through the beam. The characteristics of the measurement technique are studied analytically with an Euler-Bernoulli cantilever beam and experimental verification is performed. An approach for the numerical simulation of the measurement technique is then presented. Associated with the presented measurement technique are the short periods during which each blade is exposed to the laser beam. This characteristic yields traditional frequency domain signal processing techniques unsuitable for providing useful blade health indicators. To obtain frequency domain information from such short signals, it is necessary to employ non-standard signal processing techniques such as non-harmonic Fourier analysis. Results from experimental testing on a single-blade test rotor at a single rotor speed are presented in the form of phase angle trends obtained with non-harmonic Fourier analysis. Considering the maximum of absolute unwrapped phase angle trends around various reference frequencies, good indicators of blade health deterioration were obtained. These indicators were verified numerically. To extend the application of this condition monitoring approach, measurements were repeated on a five-blade test rotor at four different rotor speeds. Various damage cases were considered as well as different ELDV measurement positions. Using statistical parameters of the abovementioned indicators as well as time domain parameters, it is shown that with this condition monitoring approach, blade damage can successfully be identified and quantified with the aid of artificial neural networks. / Thesis (PhD)--University of Pretoria, 2010. / Mechanical and Aeronautical Engineering / unrestricted

Les ondes acoustiques et électromagnétiques offrent des méthodes de caractérisation des matériaux très peu invasives. Souvent utilisées à l'aide de capteurs indépendants, l'approche développée ici est de proposer un résonateur multimodal acoustique et électromagnétique. Afin de répondre à une grande variété d'applications, le choix de l'élément actif piézo-électrique s'est porté sur un disque de quartz de coupe AT. L'étude s'articule autour des étapes aboutissant in fine à un capteur magnéto acoustique on-chip à excitation sans contact.L'étude théorique d'un capteur magnéto-acoustique à excitation inductive est tout d'abord réalisée pour un capteur chargé par un fluide visqueux. Ce capteur est constitué de trois éléments : une sonde radiofréquence (RF), un résonateur RF à fort facteur de qualité et le quartz sur lequel ont été déposées deux électrodes en anneau. Cette étude montre comment déduire la viscosité complexe du matériau étudié à partir de l'impédance électrique du système complet. Les mesures effectuées sur des mélanges étalons montrent une très bonne correspondance avec les résultats théoriques.L'intégration du résonateur RF sur l'élément piézo-électrique s'effectuant via des électrodes circulaires, une étude préliminaire est menée sur les ondes acoustiques pouvant être générées sur le quartz et leur interaction avec les électrodes. Les mesures de vibration par vibrométrie laser montrent que des ondes de Lamb sont générées dans une large gamme de fréquence (de 100 kHz à 20 MHz). L'analyse de la réponse impulsionnelle spatiale par transformée de Gabor 3D localise la source de ces ondes sur le bord des électrodes. Par ailleurs, l'étude du disque au fondamental montre une grande non-linéarité mécanique du quartz.Le modèle de résonateur RF plan multi-tour puis son intégration sur le disque de quartz du capteur magnéto-acoustique on-chip sont ensuite étudiés. Les résultats expérimentaux par mesure d'impédance et vibrométrie laser valident le modèle. La gamme de fréquence sélectionnée (entre 5 et 20 MHz) permet d'envisager des mesures micro-rhéologiques. / Acoustic and electromagnetic waves are key probing candidates for characterizing their propagation media with minimum perturbation. Often used with independent sensors based on specialized transducing materials, the approach developed here provides an on-ship multimodal sensor using the same sensing material for probing the acoustic and electromagnetic properties of the material. To meet a wide range of applications, the choice of the active piezoelectric element is carried out on an AT cut quartz. The study focuses on the steps leading in fine to an on-chip magneto-acoustic sensor with a contactless excitation.The theoretical study of a magneto-acoustic sensor inductively excited and loaded by a viscous fluid is first carried out. This sensor consists of three elements: a radio frequency (RF) sensor, a high quality factor RF resonator and a quartz on which two ring electrodes have been deposited. The complex viscosity of the studied material is derived from the electrical impedance of the complete system. The measurements carried on etalon viscoelastic materials show a good agreement with the theoretical results.The integration of the RF resonator on the piezoelectric element being via circular electrodes, a preliminary study is performed for determining the acoustic waves that can be generated in the quartz and their interaction with the electrodes. The laser vibrometry measurements indicate that Lamb waves are generated in a wide frequency range, from 100 kHz to 20 MHz. The analysis of the spatial pulse response of the sensor surface by 3D Gabor transform locates the source of these waves on the edge of the electrodes. Furthermore, the study of the disk at it fundamental frequency points out the high nonlinear mechanical behavior of the quartz.The plane RF multi-turn resonator and its integration on the quartz disk of the magneto-acoustic on-chip sensor are then studied. The experimental results of impedance and laser vibrometry measurements validate the proposed theoretical model. The selected frequency range (between 5 and 20 MHz) allows one to consider micro rheological measurements.

Em tecidos biológicos lesados, a viscoelasticidade é a propriedade física que mais se modifica em relação ao tecido normal. Palpação manual é geralmente usada para identificar estas lesões, tais como nódulos e cistos. Recentemente, vários estudos envolvendo técnicas ultrassônicas e de ressonância magnética, denominadas elastografia, têm sido empregadas para avaliar as propriedades viscoelásticas dessas lesões. Uma das dificuldades neste tipo de estudo está relacionada ao desenvolvimento de simuladores de tecidos biológicos com inclusões equivalentes, uma vez que, essas estruturas lesadas originam-se a partir do próprio tecido biológico. Com base nessas motivações, técnicas quantitativas de elastografia por ressonância magnética e ultrassom foram exploradas para avaliar lesões simuladas em fantomas viscoelásticos. Estas lesões, com diferentes propriedades viscoelásticas, foram geradas no interior de um fantoma usando radiação ionizante. Os fantomas, também conhecidos como gel dosimétrico, foram desenvolvidos a base de pele animal, e irradiados utilizando um sistema de terapia de radiação convencional. Imagens de relaxometria por ressonância magnética (RRM) foram adquiridas nestes fantomas e usadas como referência padrão da dose absorvida e de sua distribuição. Os perfis da distribuição de dose avaliados nessas imagens de RRM e pelo sistema de planejamento radioterápico TPS 3D foram comparados aos de rigidez das imagens elastográficas. O estudo elastográfico nestes fantomas foi realizado utilizando os métodos de Vibroacustografia (VA), Vibrometria por Ultrassom (VU) e Elastografia por Ressonância Magnética (ERM). O segundo objetivo desta tese foi explorar a viabilidade de existência de speckle em imagens de vibroacustografia. Para testar essa idéia, um modelo tridimensional (3D) para a função de espalhamento de ponto (PSF) do sistema de VA foi simulada. O código da simulação foi desenvolvido em ambiente MATLAB e empregando sub-rotinas do programa Field II para simulação numérica dos transdutores. Imagens de ultrassom modo-B (IUSB) e vibroacustografia foram simuladas usando esse modelo de PSF-3D para um transdutor esférico e confocal, respectivamente. Essas IUSB foram simuladas para servir como um parâmetro comparativo com as imagens geradas por VA. As imagens de ultrassom foram exibidas em um plano tomográfico que corresponde ao plano de imagem da VA. As simulações foram realizadas utilizando um cluster de computadores de alto desempenho. Todas as imagens foram simuladas empregando um modelo de fantoma virtual não homogêneo com dimensões de (10 × 10 × 50) mm3. Os resultados preliminares mostraram um padrão de interferência nas imagens de VA, semelhantes à speckles, obtidas empregando o transdutor confocal. Estas imagens foram produzidas a partir de espalhadores localizados no interior do volume da célula de resolução da PSF-3D. / The viscoelasticity of injured biological tissues is the physical property that changes the most in relation to normal tissue. Manual palpation is commonly used to identify these lesions, such as nodules and cysts. Recently, several studies involving ultrasound and magnetic resonance imaging techniques, called elastography, have been employed to assess the viscoelastic properties of these lesions. One difficulty in this type of study is related to the development of biological tissues mimicking materials with similar inclusions, once these injured structures originate from anomalies within the biological tissue. Based on these motivations, quantitative elastographic techniques based on magnetic resonance and ultrasound modalities have been used to assess injuries in viscoelastic mimicking-tissue phantom materials. These lesions, with different viscoelastic properties, were generated within a phantom using ionizing radiation. The phantoms, also known as dosimeter gel, were developed based on animal skin powder, and irradiated using a conventional radiation therapy system. Magnetic resonance relaxometry images (MRR) were acquired in these phantoms, and were used as absorbed dose standard reference and its distribution. The estimated dose distribution profiles from these images and the ones provided by TPS 3D software radiotherapy planning system were compared to the elastograms. The elastographic studies were conducted using Vibro-acoustography (VA), Magnetic Resonance Elastography (MRE) and Shearwave Dispersion Ultrasound Vibrometry (SDUV) techniques. The second goal of this thesis was to explore the feasibility of speckle existence in vibro-acoustography images. To test that, a three-dimensional (3D) model for the systems point spread function (PSF) was simulated. The simulation code was implemented in MATLAB and using the program Field II subroutines. The numerical simulations were performed using a cluster of high performance computers. B-mode ultrasound and VA images were simulated using that PSF 3D model, for a spherically focused and a confocal transducer, respectively. These B-mode images were simulated as a comparative parameter to the images generated by VA. The B-mode ultrasound images were displayed in a tomographic plane corresponding to the VA imaging plane. All images were simulated using a virtual phantom with dimensions (10 × 10 × 50) mm3. Preliminary results showed a interference pattern in VA images taken with a confocal transducer. These images were produced from scatterers located inside the PSF resolution cell volume.

La stéréolithographie biphotonique (TPS) est une technique de microfabrication 3D basée sur la polymérisation par absorption biphotonique qui permet d’obtenir en une seule étape des structures 3D complexes avec des détails sub-100nm. Aujourd’hui, en raison des conditions spécifiques de fabrication liées à la TPS (fort flux, confinement spatial de la photoréaction,…), un des enjeux concerne le développement de matériaux fonctionnels compatibles avec ce procédé. Dans ce contexte, l’objectif de cette thèse a été de développer de nouveaux matériaux fonctionnels à base de polymères à empreintes moléculaires (MIP) pour élaborer des capteurs chimiques. Une première partie de ce travail a consisté à mettre en place différentes méthodes dédiées à la caractérisation des propriétés géométriques, chimiques et mécaniques des matériaux élaborés par TPS. Par exemple, la vibrométrie laser a été utilisée pour la première fois afin de sonder de façon non-invasive les propriétés mécaniques de microstructures réalisées par TPS. Dans un second temps, ce travail a été mis à profit pour étudier l’impact du processus de fabrication (i.e. conditions photoniques) ainsi que des paramètres physico-chimiques affectant la photoréaction (i.e. inhibition par oxygène et nature du monomère) sur les propriétés finales des matériaux. Enfin, en s’appuyant sur les résultats obtenus, des microcapteurs chimiques à base de MIP, à lecture optique ou mécanique, ont été fabriqués. Leurs propriétés de reconnaissance moléculaire, ainsi que leurs sélectivités ont été démontrées pour une molécule cible modèle (D-L-Phe). / The two-photon stereolithography (TPS) technique is a micro-nanofabrication method based on photopolymerization by two-photon absorption that allows in a single manufacturing step to obtain complex 3D structures with high-resolution details (sub-100nm). Due to the specific conditions of TPS process (intense photon flux, spatial confinement of the photoreaction…) one of the main concerns today is the development of functional materials compatible with the TPS. According to the aforementioned, the general objective of this thesis was to develop new functional materials based on molecularly imprinted polymers (MIP) to elaborate chemical microsensors. In the first step of this work, different methods were implemented to characterize the geometrical, chemical and mechanical properties of the materials synthesized by TPS. For example, laser-Doppler vibrometry was used for first time to evaluate the mechanical properties of microstructures fabricated by TPS in a non-invasive way. In the second step, the characterization methodology was used to study the impact of the manufacturing process (i.e. photonic conditions) and the physicochemical parameters that affect the photoreaction (i.e. oxygen inhibition and the nature of the monomer) and the final properties of the materials. Finally, the obtained results enabled the prototyping of chemical microsensors based on MIP. Their molecular recognition properties and their selectivity were demonstrated for the molecule (D-L-Phe) by an optical and a mechanical sensing method.

Em tecidos biológicos lesados, a viscoelasticidade é a propriedade física que mais se modifica em relação ao tecido normal. Palpação manual é geralmente usada para identificar estas lesões, tais como nódulos e cistos. Recentemente, vários estudos envolvendo técnicas ultrassônicas e de ressonância magnética, denominadas elastografia, têm sido empregadas para avaliar as propriedades viscoelásticas dessas lesões. Uma das dificuldades neste tipo de estudo está relacionada ao desenvolvimento de simuladores de tecidos biológicos com inclusões equivalentes, uma vez que, essas estruturas lesadas originam-se a partir do próprio tecido biológico. Com base nessas motivações, técnicas quantitativas de elastografia por ressonância magnética e ultrassom foram exploradas para avaliar lesões simuladas em fantomas viscoelásticos. Estas lesões, com diferentes propriedades viscoelásticas, foram geradas no interior de um fantoma usando radiação ionizante. Os fantomas, também conhecidos como gel dosimétrico, foram desenvolvidos a base de pele animal, e irradiados utilizando um sistema de terapia de radiação convencional. Imagens de relaxometria por ressonância magnética (RRM) foram adquiridas nestes fantomas e usadas como referência padrão da dose absorvida e de sua distribuição. Os perfis da distribuição de dose avaliados nessas imagens de RRM e pelo sistema de planejamento radioterápico TPS 3D foram comparados aos de rigidez das imagens elastográficas. O estudo elastográfico nestes fantomas foi realizado utilizando os métodos de Vibroacustografia (VA), Vibrometria por Ultrassom (VU) e Elastografia por Ressonância Magnética (ERM). O segundo objetivo desta tese foi explorar a viabilidade de existência de speckle em imagens de vibroacustografia. Para testar essa idéia, um modelo tridimensional (3D) para a função de espalhamento de ponto (PSF) do sistema de VA foi simulada. O código da simulação foi desenvolvido em ambiente MATLAB e empregando sub-rotinas do programa Field II para simulação numérica dos transdutores. Imagens de ultrassom modo-B (IUSB) e vibroacustografia foram simuladas usando esse modelo de PSF-3D para um transdutor esférico e confocal, respectivamente. Essas IUSB foram simuladas para servir como um parâmetro comparativo com as imagens geradas por VA. As imagens de ultrassom foram exibidas em um plano tomográfico que corresponde ao plano de imagem da VA. As simulações foram realizadas utilizando um cluster de computadores de alto desempenho. Todas as imagens foram simuladas empregando um modelo de fantoma virtual não homogêneo com dimensões de (10 × 10 × 50) mm3. Os resultados preliminares mostraram um padrão de interferência nas imagens de VA, semelhantes à speckles, obtidas empregando o transdutor confocal. Estas imagens foram produzidas a partir de espalhadores localizados no interior do volume da célula de resolução da PSF-3D. / The viscoelasticity of injured biological tissues is the physical property that changes the most in relation to normal tissue. Manual palpation is commonly used to identify these lesions, such as nodules and cysts. Recently, several studies involving ultrasound and magnetic resonance imaging techniques, called elastography, have been employed to assess the viscoelastic properties of these lesions. One difficulty in this type of study is related to the development of biological tissues mimicking materials with similar inclusions, once these injured structures originate from anomalies within the biological tissue. Based on these motivations, quantitative elastographic techniques based on magnetic resonance and ultrasound modalities have been used to assess injuries in viscoelastic mimicking-tissue phantom materials. These lesions, with different viscoelastic properties, were generated within a phantom using ionizing radiation. The phantoms, also known as dosimeter gel, were developed based on animal skin powder, and irradiated using a conventional radiation therapy system. Magnetic resonance relaxometry images (MRR) were acquired in these phantoms, and were used as absorbed dose standard reference and its distribution. The estimated dose distribution profiles from these images and the ones provided by TPS 3D software radiotherapy planning system were compared to the elastograms. The elastographic studies were conducted using Vibro-acoustography (VA), Magnetic Resonance Elastography (MRE) and Shearwave Dispersion Ultrasound Vibrometry (SDUV) techniques. The second goal of this thesis was to explore the feasibility of speckle existence in vibro-acoustography images. To test that, a three-dimensional (3D) model for the systems point spread function (PSF) was simulated. The simulation code was implemented in MATLAB and using the program Field II subroutines. The numerical simulations were performed using a cluster of high performance computers. B-mode ultrasound and VA images were simulated using that PSF 3D model, for a spherically focused and a confocal transducer, respectively. These B-mode images were simulated as a comparative parameter to the images generated by VA. The B-mode ultrasound images were displayed in a tomographic plane corresponding to the VA imaging plane. All images were simulated using a virtual phantom with dimensions (10 × 10 × 50) mm3. Preliminary results showed a interference pattern in VA images taken with a confocal transducer. These images were produced from scatterers located inside the PSF resolution cell volume.

Structures made of the thermoplastic polymer polyether ether ketone (PEEK) are widely used in dynamically-loaded applications due to their high-temperature resistance and high mechanical properties. To design these dynamic applications, in addition to the well-known stiffness and strength properties the vibration-damping properties at the given frequencies are required. Depending on the application, frequencies from a few hertz to the ultrasonic range are of interest here. To characterize the frequency-dependent behavior, an experimental approach was chosen and applied to a sample polymer PEEK. The test setup consists of a piezoelectrically driven base excitation of the polymeric specimen and the non-contact measurement of the velocity as well as the surface temperature. The beam’s bending vibrations were analyzed by means of the Timoshenko theory to determine the polymer’s storage modulus. The mechanical loss factor was calculated using the half-power bandwidth method. For PEEK and a considered frequency range of 1 kHz to 16 kHz, a storage modulus between 3.9 GPa and 4.2 GPa and a loss factor between 9 103 and 17 103 were determined. For the used experimental parameters, the resulting mechanical properties were not essentially influenced by the amplitude of excitation, the duration of excitation, or thermal degrad.ation due to self-heating, but rather slightly by the clamping force within the fixation area.

In der vorliegenden Arbeit werden der Entwurf, die Technologie und die Parameteridentifikation von Silizium basierten mikroelektromechanischen Systemen (MEMS) mit piezoelektrischen Dünnschicht-Aluminiumnitrid (AlN) vorgestellt. Auf Basis des AlNs als elektromechanischer Wandler erfolgt die Fertigung eines MEMS Technologiedemonstrators für energiearme Inertialsensoren. Das AlN wird über einen reaktiven Sputterprozess auf einer Wachstumsschicht abgeschieden. Durch Parametervariation des reaktiven Sputterprozesses und der Wachstumsschicht werden die piezoelektrischen Eigenschaften des AlNs optimiert. Die Entwicklung einer Gesamttechnologie führt zu einer Integration des Dünnschicht-AlNs in Silizium-Mikromechaniken. Die Röntgenbeugung (XRD) ermöglicht die Kristallstruktur des AlNs zu qualifizieren. Darüber hinaus werden weitere Analysemethoden vorgestellt, die eine hoch genaue und reproduzierbare messtechnische Bestimmung der piezoelektrischen Koeffizienten aus mikromechanischen Messstrukturen ermöglichen. Die Determination der piezoelektrischen Koeffizienten des Dünnschicht-AlNs aus den Messstrukturen erfolgt mittels analytischen und FE Modellen sowie der Laser-Doppler-Vibrometrie (LDV). Der Fokus der Arbeit liegt hierbei auf der Identifikation der longitudinalen und transversalen piezoelektrischen Ladungskoeffizienten des AlNs. Als Technologiedemonstrator wird ein einachsiger Inertialsensor mit integriertem piezoelektrischen Dünnschicht-AlN vorgestellt. Das MEMS generiert aufgrund des piezoelektrischen Wandlers intrinsisch elektrische Ladungen bei Einwirkung einer mechanischen Energie. Dadurch ist keine elektrische Energiezufuhr für die Messung eines inertialen Ereignisses notwendig. Der vorgestellte Demonstrator wird hinsichtlich seiner Ladungs- und Spannungssensitivität optimiert. Zur theoretischen Beschreibung der Funktionsweise werden analytische, sowie FE und SPICE Modelle genutzt. Eine Charakterisierung des MEMS Bauelements erfolgt hinsichtlich der mechanischen und elektrischen Eigenschaften. / The thesis includes the design, the technology and the parameter identification of silicon-based microelectromechanical systems (MEMS) with piezoelectric thin film of aluminum nitride (AlN). A low-energy inertial sensor as technology demonstrator based on AlN as an electromechanical transducer a MEMS manufacturing process is shown. The AlN is deposited via a reactive sputtering on a growth layer. By varying parameters of the reactive sputtering and the growth layer of AlN, the piezoelectric properties can be optimized. The development of an overall technology results to an integration of the thin film AlNs in silicon micromechanics. X-ray diffraction (XRD) allows to qualify the crystal structure of AlN. Further methods are developed that enable a highly accurate and repeatable metrological determination of piezoelectric coefficients measurement structures. The determination of piezoelectric coefficients of the thin film AlN from the measurement structures is resulting from analytical methods and FE models and the laser Doppler vibrometry (LDV). The identification of the longitudinal and transverse piezoelectric charge coefficient of AlN is one main focus of this work. A uniaxial inertial sensor with an integrated piezoelectric thin film of AlN is presented as technology demonstrator. The piezoelectric transducer of the MEMS is generating electric charges intrinsically as reaction of mechanical stress. Thus, no electric power supply for the measurement of an inertial event is necessary. The presented demonstrator has been optimized with respect to its charge and voltage sensitivity. For a theoretical description analytical and FE and SPICE models are used. A characterization of the MEMS device is carried out with regard to the mechanical and electrical properties.

This thesis presents a body of work on the theme of millimetre-wave FMCW radar, for the purposes of security screening and remote sensing. First, the development of an optimised software radar signal processor will be outlined. Through use of threading and GPU acceleration, high data processing rates were achieved using standard PC hardware. The flexibility of this approach, compared to specialised hardware (e.g. DSP, FPGA etc…), allowed the processor to be rapidly adapted and has produced a significant performance increase in a number of advanced real-time radar systems. An efficient tracker was developed and was successfully deployed in live trials for the purpose of real-time wave detection in an autonomous boat control system. Automated radar operation and remote data telemetry functions were implemented in a terrain mapping radar to allow continuous monitoring of the Soufrière Hills volcano on the Caribbean island of Montserrat. This work concluded with the installation of the system 3 km from the volcano. Hardware modifications were made to enable coherent measurement in a number of existing radar systems, allowing phase sensitive measurements, including range-Doppler, to be performed. Sensitivity to displacements of less than 200 nm was demonstrated, which is limited by the phase noise of the system. Efficient compensation techniques are presented which correct for quadrature mixer imbalance, FMCW chirp non-linearity, and scanner drive distortions. In collaboration with the Home Office, two radar systems were evaluated for the stand-off detection of concealed objects. Automatic detection capability, based on polarimetric signatures, was developed using data gathered under controlled conditions. Algorithm performance was assessed through blind testing across a statistically significant number of subjects. A detailed analysis is presented, which evaluates the effect of clothing and object type on detection efficiency.

In der vorliegenden Arbeit wird eine Methode zur Charakterisierung von Mikrosystemen mit beweglichen Komponenten dargestellt. Sie erlaubt, funktionsrelevante Parameter und deren Schwankungen produktionsbegleitend auf Waferlevel zu ermitteln. Dabei wird vorausgesetzt, dass die Sollform der Struktur und die Abweichungsarten bekannt sind. Die Methode beruht auf dem Vergleich von numerisch berechneten mit experimentell ermittelten Eigenfrequenzen der untersuchten Mikrosysteme. Dazu wird die Abhängigkeit verschiedener Eigenfrequenzen von den gesuchten Parametern mittels einer Parametervariationsanalyse berechnet und durch eine geeignete Funktion angenähert. Die Messung der dynamischen Eigenschaften erfolgt mit Hilfe eines Bewegungsanalysators, der auf einem Laser-Doppler-Vibrometer basiert. Im letzen Schritt werden die gesuchten Parameter berechnet. Kernpunkt der entwickelten Methode sind Messungen auf der Basis von speziellen Teststrukturen, die im Waferlayout neben den eigentlichen Nutzstrukturen platziert sind und parallel mit den Nutzstrukturen prozessiert werden. Es werden Algorithmen zur Generierung des Designs der Teststrukturen und ihrer Platzierung im Waferlayout entwickelt. Dabei werden das Design der Nutzstruktur und deren funktionsrelevante Parameter, der technologische Ablauf und materialspezifische Kennwerte berücksichtigt. Im Ergebnis liegt eine Bibliothek von Standard-Teststrukturen vor, die für produktionsbegleitende Messungen sowie für die Übertragbarkeit der Ergebnisse geeignet sind. Außerdem werden allgemeingültige Richtlinien zur Durchführung der Messungen an den Standard-Teststrukturen abgeleitet. Das Messverfahren wurde an unterschiedlichen Mikrosystemen mit beweglichen Komponenten überprüft und zu einer allgemeinen Messmethode für diese Klasse von Mikrosystemen erweitert. / In this work a method for the characterization of microsystems with movable components is presented. The method allows to determine the relevant parameters and their variations on wafer level if the nominal shape of the structure and the type of deviations are known. The method is based on a comparison of the numerically calculated and experimentally measured Eigenfrequencies of the microsystems. For that purpose, the relationships between various Eigenfrequencies and the searched parameters are calculated by parameter variation analysis and the results of this analysis are approximated with appropriate functions. A Laser Doppler vibrometer based motion analyzer is used to determine the frequency response function of the micromechanical structure and extract Eigenfrequencies. The comparison of the measured and the calculated frequencies provides values for the searched parameters. The key element of the developed method is the measurement on special test structures that are placed in the wafer layout next to the actual microsystems and processed in the same technological process parallel to the actual microsystems. Algorithms for designing the test structures and their placement in the wafer layout are shown, taking into account the design of the actual microsystems and the function parameters of the technological process as well as material characteristics. As a result, a library of standard test structures for function relevant parameters is available. A general guideline for the measurement on the test structures is presented. The presented method is verified on various microsystems and extended to a whole class of microsystems with movable components.