Nano-FET biosensors are an emerging nanoelectronic technology capable of real-time and label-free quantification of soluble biological molecules. This technology promises to enable novel in vitro experimental approaches for investigating complex biological systems. In this study, we first explored osteocyte mechanosensitivity under different mechanical stimuli and found that osteocytes are exquisitely sensitive to different oscillatory fluid flow conditions. We therefore aimed to characterize protein-mediated intercellular communication between mechanically-stimulated osteocytes and other bone cell populations in vitro to elucidate the underlying mechanisms of load-induced bone remodeling. To this end, we devised a novel nano-manipulation based fabrication method for manufacturing nano-FET biosensors with precisely controlled device parameters, and further investigated the effect of these parameters on sensor performance.

Le travail présenté dans ce mémoire s'inscrit dans le cadre des problèmes d'intégration des dispositifs électriques en général et des composants passifs en particulier permettant de réaliser des systèmes de conversion intégrés. Le travail débute avec l'étude et la caractérisation de transformateurs piézoélectriques de taille " méso " de quelques fractions de watts à quelques watts destinées à la mise en œuvre d'une commande rapprochée de transistors de puissance MOSFET & IGBT intégrée sur un substrat en PCB. Il se place ensuite dans la problématique de l'intégration sur silicium de micro-transformateur piézoélectriques pour des systèmes d'alimentation électrique de quelques micro-watts. L'objectif est d'établir de nouvelles structures de micro-transformateur, exploitant des couches minces d'AlN et de PZT déposées par pulvérisation cathodique, dont les étapes de fabrication sont compatibles avec les technologies et les contraintes de la microélectronique.

The development and fabrication of silicon-based phononic band gap crystals has been gaining interest since phononic band gap crystals have implications in fundamental science and display the potential for application in engineering by providing a relatively new platform for the realization of sensors and signal processing elements. The seminal study of phononic band gap phenomenon for classical elastic wave localization in structures with periodicity in two- or three-physical dimensions occurred in the early 1990’s. Micro-integration of silicon devices that leverage this phenomenon followed from the mid-2000’s until the present. The reported micro-integration relies on exotic piezoelectric transduction, phononic band gap crystals that are etched into semi-infinite or finite-thickness slabs which support surface or slab waves, phononic band gap crystals of numerous lattice constants in dimension and phononic band gap crystal truncation by homogeneous mediums or piezoelectric transducers. The thesis reports, to the best of the author's knowledge, for the first time, the theory, design methodology and experiment of an electrostatically actuated silicon-plate phononic band gap quasi-crystal architecture, which may serve as a platform for the development of a new generation of silicon-integrated sensors, signal processing elements and improved mechanical systems. Electrostatic actuation mitigates the utilization of piezoelectric transducers and provides action at a distance type forces so that the phononic band gap quasi-crystal edges may be free standing for potentially reduced anchor and substrate mode loss and improved energy confinement compared with traditional surface and slab wave phononic band gap crystals. The proposed phononic band gap quasi-crystal architecture is physically scaled for fabrication as MEMS in a silicon-on-insulator process. Reasonable experimental verification of the model of the electrostatically actuated phononic band gap quasi-crystal architecture is obtained through extensive dynamic harmonic analysis and mode shape topography measurements utilizing optical non-destructive laser-Doppler velocimetry. We have utilized our devices to obtain fundamental information regarding novel transduction mechanisms and behavioral characteristics of the phononic band gap quasi-crystal architecture. Applicability of the phononic band gap quasi-crystal architecture to physical temperature sensors is demonstrated experimentally. Vibration stabilized resonators are demonstrated numerically.

Methicillin Resistant Staphylococcus aureus (MRSA) is one of the most important threats of nosocomial infections in many regions of the world and Vancomycin Resistant Enterococcus (VRE) is an emerging pathogen that develops full resistance against third-generation glycopeptide antibiotics. Conventional methods for identification of MRSA and VRE generally depend on culturing, which requires incubation of biological samples at least 24-72 hours to get accurate results. These methods are time consuming and necessitate optical devices and experts for evaluation of the results. On the other hand, early diagnosis and initiation of appropriate treatment are necessary to decrease morbidity and mortality rates. Thus, new diagnostic systems are essential for rapid and accurate detection of biological analytes at the point of care. This study presents design, fabrication, and implementation of MEMS based micro electrochemical sensor (&micro / ECS) to detect the methicillin resistance in Staphylococcus aureus and vancomycin resistance in Enterococcus species. To the best of our knowledge, the developed sensor is the first &micro / ECS which utilizes on-chip reference (Ag), working (Au), and counter (Pt) electrodes together with a microchannel to detect MRSA and VRE. The characterization of the designed sensor was achieved analyzing the interactions of the buffer solutions and solvents with the electrodes and Parylene C film layer by using optical and electrochemical methods. Specific parts of genes that are indicators of antimicrobial resistances were used in order to detect the resistances with high selectivity and sensitivity. Thus, synthetic DNA and bacterial PCR product were used as target probes in redox marker based detection and enzyme based detection, respectively. In order to enhance the hybridization, folding structures of the capture probe were investigated by using mfold Web Server. In redox marker based detection, the hybridization of DNA was indirectly detected by using Hoechst 33258 as redox marker with differential pulse voltammetry. The cross reactivity of the tests were performed by using different target probes of femA genes of S. aureus and S. epidermis, which are the major genes detected in methicillin detection assays. Consequently, amplification of signal by using horseradish peroxidase and TMB/H2O2 as substrate was achieved in order to enhance detection sensitivity. The sensor could detect 0.01 nM 23-mer specific part of mecA gene with redox marker based detection and 10 times diluted PCR product with enzyme-based detection in about six hours including the steps of sample preparation from whole blood. This sensor with its compatibility to MEMS fabrication processes and IC technology has a promising potential for a hand-held device for POC through the integration of micropotentiostat.

The mechanical properties of biomaterials play important roles in performing their specialized functions: synthesizing, storing, and transporting biomolecules; maintaining internal structures; and responding to external environments. Besides biological cells, there are also many other biomaterials that are highly deformable and have a diameter between 1μm and 100μm, comparable to that of most biological cells. For example, many polymeric microcapsules for drug delivery use are spherical particles of micrometers size. In order to mechanically characterize individual micrometer-sized biomaterials, the capability of capturing high-resolution and low-magnitude force feedback is required. This research focuses on the development of micro devices and experimental techniques for quantifying the mechanical properties of alginate-chitosan microcapsules. The micro devices include microelectromechanical systems (MEMS) capacitive force sensors and force-feedback microgrippers, capable of measuring sub-μN forces. Employing the MEMS devices, systems were constructed to perform the micro-scale compression testing of microcapsules. The force sensors are capable of resolving forces up to 110μN with a resolution of 33.2nN along two independent axes. The force sensors were applied to characterizing the mechanical properties of hydrogel microparticles without assembling additional end-effectors. The microcapsules were immobilized by a PDMS holding device and compressed between the sensor probe and holding device. Young's modulus values of individual microcapsules with 1%, 2%, and 3% chitosan coating were determined through the micro-scale compression testing in both distilled deionized (DDI) water and pH 7.4 phosphate buffered saline (PBS). The Young's modulus values were also correlated to protein release rates. Instead of compressing the microcapsule against the wall of the holding device, a force-feedback MEMS microgripper with the capability of directly compressing the microcapsule between two gripping arms has been used for characterizing both the elastic and viscoelastic properties of the microcapsules during micromanipulation. The single-chip microgripper integrates an electrothermal microactuator and two capacitive force sensors, one for contact detection (force resolution: 38.5nN) and the other for gripping force measurements (force resolution: 19.9nN). Through nanoNewton force measurements, closed-loop force control, and visual tracking, the system quantified the Young's modulus values and viscoelastic parameters of alginate microcapsules, demonstrating an easy-to-operate, accurate compression testing technique for characterizing soft, micrometer-sized biomaterials.

En aquest treball s'ha establert una metodologia d'anàlisi i caracterització del comportament tèrmic, mecànic i termomecànic d'estructures micromecanitzades per a sensors de gas a través de la combinació de simulacions numèriques i tècniques de caracterització de microsistemes (mesures electro-tèrmiques, termografia, nanoindentació, AFM, XRD, microscopia confocal, Auger).L'estudi del comportament tèrmic de les estructures micromecanitzades ha permès obtenir les característiques bàsiques que controlaran el comportament del sensor, com són el consum en potència, la distribució de temperatura i el temps de resposta del substrat. L'anàlisi termomecànic ha consistit en determinar els esforços residuals en cada estructura així com l'estudi de la deformació dels diferents dissenys per a diferents temperatures de treball. S'han identificat diferents mecanismes de degradació en els materials que formen els sensors i s'ha obtingut el comportament termomecànic fins la ruptura del sensor. Tant en l'estudi tèrmic com en el termomecànic, la interacció entre la capa sensora i el substrat micromecanitzat així com l'influencia del material sensor en el comportament global del dispositiu han estat aspectes investigats.El treball inclou, a més, la caracterització termomecànica del Pt-Ti emprat en estructures micromecanitzades a través de la utilització de mètodes de Nanoindentació, Microscopia de Forces Atòmiques (AFM), Difracció de Raigs X (XRD) i espectroscopia Auger. També inclou el desenvolupament d'una metodologia per predir la fatiga tèrmica en microsistemes basada en la combinació dels models elasto-plàstics de metalls en capa prima (Alumini, Pt-Ti) amb simulacions numèriques. Finalment, de la metodologia d'anàlisi electro-termo-mecànic que s'ha dut a terme, es poden obtenir regles de disseny per la implementació de microsistemes que treballin en diferents règims de temperatura i en concret, directament aplicables al disseny i fabricació d'estructures micromecanitzades per a sensors de gas / This work presents a complete thermomechanical study of different micromachined gas sensor substrates based on closed and suspended membrane microstructures. The work has been carried out combining coupled electro-thermo-mechanical three-dimensional finite element method simulations with different experimental techniques such as those used in Microsystems characterization (thermo-electrical, thermography, AFM, XRD, confocal microscopy, Auger..). The performances predicted by simulations, such as the power consumption, the temperature distribution, the time response, the membrane deflection during operation and the preferential failure sites in the micromachined substrates have been confirmed by experience. The work includes the thermo-mechanical characterization of Pt-Ti thin films used in the structures using Nanoindentation, AFM, XRD and Auger spectroscopy. Additionally, a methodology to predict the thermal fatigue in microsystems, which combines experimental thin metal elasto-plastic models (Al, Pt-Ti) and coupled thermo-mechanical FEM simulations, has been developed.The good agreement between simulations and experimental results validates the numerical models, and allows us to consider the adaptability of the analyzed designs as micromachined substrates for integrated gas sensors.Keywords: MEMS, Microsystems, gas sensors, thermal fatigue, Al, Pt-Ti, FEM. / En este trabajo se ha establecido una metodología de análisis y caracterización térmica y termomecánica de estructuras micromecanizadas en silicio para aplicaciones en sensores de gas. Esta investigación ha combinado simulaciones numéricas mediante el método de los elementos finitos con técnicas experimentales de caracterización utilizadas en el campo de los microsistemas (medidas electro-térmicas, termografía, AFM, XRD, microscopia confocal, Auger).El estudio térmico de dichas estructuras ha permitido obtener su consumo en potencia, la distribución de temperaturas, la dinámica térmica, así como ha permitido fijar con precisión las propiedades térmicas de los materiales típicamente utilizados en la tecnología de los microsistemas. El estudio mecánico ha permitido obtener los esfuerzos residuales inducidos por los procesos de fabricación. Además, se ha obtenido la deformación de las estructuras a diferentes temperaturas de trabajo hasta la ruptura total de las membranas. Durante las altas temperaturas de trabajo se han detectado y analizado diferentes mecanismos de degradación en los materiales. El trabajo incluye además, la caracterización termo-mecánica del Pt-Ti depositado por sputtering, ampliamente utilizado en microsensores de gas, mediante el empleo de técnicas de Nanoindentación, Microscopia AFM, Difracción de Rayos X (XRD) y espectrocopia Auger. También presenta el desarrollo de una metodología para la predicción de la fatiga térmica en microsistemas, que se basa en la combinación de modelos elasto-plásticos para metales en capa delgada con simulaciones numéricas.Finalmente, de la metodología de análisis termo-mecánico que se ha llevado a cabo, se pueden obtener reglas de diseño para microsistemas que trabajen a diferentes temperaturas, y en concreto directamente aplicables al diseño y fabricación de estructuras micromecanizadas para sensores de gas. Palabras clave: MEMS, microsistemas, sensores de gas, fatiga térmica, Al, Pt-Ti, MEF.

The recent breakthroughs in genomics and molecular diagnostics will not be reflected in health-care systems unless the biogenetic or other nucleic acid-based tests are transferred from the laboratory to clinical market. Developments in microfabrication techniques brought lab-on-a-chip (LOC) into being the best candidate for conducting sample preparation for such clinical devices, or point-of-care testing set-ups. Sample preparation procedure consists of several stages including cell transportation, separation, cell lysis and nucleic acid purification and detection. LOC, as a subset of Microelectromechanical systems (MEMS), refers to a tiny, compact, portable, automated and easy-to-use microchip capable of performing the sample-preparation stages together. Complexity in micro-fabrications and inconsistency of the stages oppose integration of them into one chip. Among the variety of mechanisms utilized in LOC for cell lysis, electrical methods have the highest potential to be integrated with other microchip-based mechanisms. There are, however, major limitations in electrical cell lysis methods: the difficulty and high-cost fabrication of microfluidic chips and the high voltage requirements for cell lysis. Addressing these limitations, the focus of this thesis is on realization of cell lysis microchips suitable for LOC applications. We have developed a new methodology of fabricating microfluidic chips with electrical functionality. Traditional lithography of microchannel with electrode, needed for making electro-microfluidic chips, is considerably complicated. We have combined several easy-to-implement techniques to realize electro-microchannel with laser-ablated polyimide. The current techniques for etching polyimide are by excimer lasers in bulky set-ups and with involvement of toxic gas. We present a method of ablating microfluidic channels in polyimide using a 30W CO2 laser. Although this technique has poorer resolution, this approach is more cost effective, safer and easier to handle. We have verified the performance of the fabricated electro-microfluidic chips on electroporation of mammalian cells. Electrical cell lysis mechanisms need an operational voltage that is relatively high compared to other cell manipulation techniques, especially for lysing bacteria. Microelectro-devices have dealt with this limitation mostly by reducing the inter-distance of electrodes. The technique has been realized in tiny flow-through microchips with built-in electrodes in a distance of a few micrometers which is in the scale of cell size. In addition to the low throughput of such devices, high probability of blocking cells in such tiny channels is a serious challenge. We have developed a cell lysis device featured with aligned carbon nanotube (CNT) to reduce the high voltage requirement and to improve the throughput. The vertically aligned CNT on an electrode inside a MEMS device provides highly strengthened electric field near the tip. The concept of strengthened electric field by means of CNT has been applied in field electron emission but not in cell lysis. The results show that the incorporation of CNT in lysing bacteria reduces the required operational voltage and improves throughput. This achievement is a significant progress toward integration of cell lysis in a low-voltage, high-throughput LOC. We further developed the proposed fabrication methodology of micro-electro-fluidic chips, described earlier, to perform electroporation of single mammalian cell. We have advanced the method of embedding CNT in microchannel so that on-chip fluorescent microscopy is also feasible. The results verify the enhancement of electroporation by incorporating CNT into electrical cell lysis. In addition, a novel methodology of making CNT-embedded microfluidic devices has been presented. The embedding methodology is an opening toward fabrication of a CNT-featured LOC for other applications.

Le sujet de thèse porte sur des micro/nanorésonateurs ainsi que leurs électroniques de lecture. Les composants mécaniques sont utilisés pour mesurer des masses inférieures à l'attogramme (10-18 g) ou de très faibles concentrations de gaz. Ces composants peuvent ensuite être mis en réseau afin de réaliser des spectromètres de masse ou des détecteurs de gaz. Afin d'atteindre les résolutions nécessaires, il a été choisi d'utiliser une détection harmonique de résonance détectant les variations de la fréquence de résonance d'une nanostructure mécanique. Les dimensions du résonateur sont réduites afin d'augmenter sensibilité en masse, cependant le niveau du signal électrique en sortie du composant est également réduit. Ce faible signal nécessite donc de concevoir de nouvelles transductions électromécaniques ainsi que des architectures électroniques qui minimisent le bruit, les couplages parasites et qui peuvent être mise en réseau.

RF/microwave tunable filters are widely employed in radar systems, measurement instruments, and communication systems. By using tunable filters, the frequency bandwidth is utilized effectively and the system cost and complexity is reduced. In the literature, various tuning techniques have been developed to construct tunable filters. Mechanical tuning, magnetic tuning, and electrical tuning are the most common. In terms of quality factor, power handling capability, and linearity, mechanical tuning is superior to the other two tuning techniques. Unfortunately, due to their bulky size, heavy weight, and low tuning speed, mechanically tunable filters have limited applications. MicroElectroMechanical Systems (MEMS) technology has the potential to produce highly miniaturized tunable filters; however, most of the MEMS tunable filters reported so far have a relatively low quality factor. The objective of the research described in this thesis is to investigate the feasibility of using MEMS technology to develop tunable filters with a high quality factor. The integration of MEMS tuning elements with a wide range of filter configurations is explored, from micromachined filters to traditional dielectric resonator filters, from planar filters to cavity filters. Both hybrid integration and monolithic integration approaches are carried out. To achieve tunability, MEMS tuning elements are embedded within RF and microwave filters. Tuning is accomplished by disturbing the electromagnetic fields of resonators with nearby MEMS tuning elements, which in turn change the resonant frequency of the resonators. First, the proposed tuning concept is experimentally demonstrated by integrating a surface micromachined planar filter with MEMS thermal actuators as the tuning elements. Then, a novel micromachined ridge waveguide filter embedded with similar MEMS tuning elements is proposed and constructed by using the EFAB^{TM} micromachining technique. A power handling analysis is performed for the newly devised 3D micromachined filter, and potential failure mechanisms such as air breakdown are identified. For the first time, a tunable dielectric resonator bandpass filter, incorporating vertical long-throw MEMS thermal actuators as tuning elements, is developed to achieve a wide tuning range, high quality factor, and large power handling capability. Several prototype tunable filter units are fabricated and tested. The experimental results reveal that the tunable filters maintain a relatively high quality factor value over a wide tuning range. In addition to the hybrid integration approach, a monolithic integration approach is investigated. A novel surface micromachining process is developed to allow monolithic integration of MEMS tuning elements into micromachined filters. Due to a stress mismatch, MEMS actuators fabricated by this process obtain a vertical deflection of several hundred microns, resulting in a wide tuning range. Various latching mechanisms are created, based on the micromachining processes that are used to fabricate the MEMS tuning elements. These out-of-plane latching mechanisms with multi-stable states have the potential to be adopted not only for tunable filter applications but also for switches and phase shifters.

This research focuses on developing new techniques and designs for highly con- trollable microactuating systems with large force-stroke outputs. A fixed-fixed mi- crobeam is the actuating element in the introduced techniques. Either buckling of a microbridge by thermal stress, lateral deflection of a microbridge by electro- magnetic force, or combined effects of both can be employed for microactuation. The proposed method here is MicroElectroThermoMagnetic Actuation (METMA), which uses the combined techniques of electrical or electro-thermal driving of a mi- crobridge in the presence of a magnetic field. The electrically controllable magnetic field actuates and controls the electrically or electrothermally driven microstruc- tures. METMA provides control with two electrical inputs, the currents driving the microbridge and the current driving the external magnetic field. This method enables a more controllable actuating system. Different designs of microactuators have been implemented by using MEMS Pro as the design software and MUMPs as the standard MEMS fabrication technology. In these designs, a variety of out-of- plane buckling or displacement of fixed-fixed microbeams have been developed and employed as the actuating elements. This paper also introduces a novel actuating technique for larger displacements that uses a two-layer buckling microbridge actu- ated by METMA. Heat transfer principles are applied to investigate temperature distribution in a microbeam, electrothermal heating, and the resulting thermoelas- tic effects. Furthermore, a method for driving microactuators by applying powerful electrical pulses is proposed. The integrated electromagnetic and electrothermal microactuation technique is also studied. A clamped-clamped microbeam carry- ing electrical current has been modeled and simulated in ANSYS. The simulations include electrothermal, thermoelastic, electromagnetic, and electrothermomagnetic effects. The contributions are highlighted, the results are discussed, the research and design limitations are reported, and future works are proposed.