Multiplexing has evolved over the years from Emile Baudot's method of transmitting six simultaneous telegraph signals over one wire to the high-speed mixed-signal communications systems that are now commonplace. The evolution started with multiplexing identical information sources, such as plain old telephone service (POTS) devices. Recently, however, methods to combine signals from different information sources, such as telephone and video signals for example, have required new approaches to the development of software and hardware, and fundamental changes in the way we envision the basic block diagrams of communication systems. The importance of multiplexing cannot be overstated. To say that much of the current economic and technological progress worldwide is due in part to mixed-signal communications systems would not be incorrect. Along the vein of advancing the state-of-the-art, this dissertation research addresses a new area of multiplexing by taking a novel approach to network different-type sensors using software and signal processing. Two different sensor types were selected, fiber optics and MEMS, and were networked using code division multiplexing. The experimentation showed that the interconnection of these sensors using code division multiplexing was feasible and that the mixed signal demultiplexing software unique to this research allowed the disparate signals to be discerned. An analysis of an expanded system was performed with the results showing that the ultimate number of sensors that could be multiplexed with this technique ranges from the hundreds into the millions, depending on the specific design parameters used. Predictions about next-next generation systems using the techniques developed in the research are presented. / Ph. D.

The detection and identification of particles within fluid samples is key in the prevention of the spreading of disease. This has created a growing need for devices able to successfully separate and identify multiple particles for this purpose while operating at a high enough throughput to be applicable in the field. A well investigated method of manipulating particles in this way is Dielectrophoresis (DEP), which is the use of varied electric fields gradients to generate a force on small particles. The strength of DEP depends of the properties of the particle medium, the signal generating the electric field, and the properties of the particles themselves. This method and its interaction with all small particles, including biological particles such as blood and cancer cells, has allowed devices utilizing this idea to be investigated for various biological purposes. This thesis investigates methods to increase the throughput of these types of devices in order to increase their ability to process large amounts of samples in reasonable amounts of time. This is done in primarily two methods. One approach uses the application of chromatographic methods to DEP devices to separate particles by altering their individual transit time through a device, allowing identification during constant flow. Another method is through mass parallel channels which each individually operate as a standard DEP particle trapping device. This allows for the summation of the maximum flow through the device due to its design layout. / Master of Science / Micrometer scale devices are popular for the identification, separation, and characterization of micron scale particles. This includes uses in biological fields for the manipulation of particles such as blood cells, cancer cells, and bacteria. A common method of manipulating these particles is Dielectrophoresis, a force that causes particles to be repelled or attracted to geometric designs within the device generated by an applied electric field. The strength and direction of this force on the particles is dependent on the properties of the electrical signal applied to the device, the physical properties of the particles, such as size and shape, and the properties of the medium the particles are suspended in within the device. Biological devices utilizing this force have been tested before, allowing for particles to be separated out of mixed particle solutions. Most of these devices operate by moving through very little material at one time, somewhere in the microliter per hour range. This thesis explores attempts to increase the rate at which samples can be processed by these devices in multiple ways. Chapter 2 explores methods of DEP by applying Chromatography principles, which is to constantly move samples through the device at a high rate and slow the target particles, so they exit the device at a different time than other particles. Chapter 3 investigates increasing device throughput by replicating a standard DEP channel multiple times on one device so that several may operate all at once.

Micro-Electro-Mechanical Systems (MEMS) varactors have the potential to replace conventional varactor diodes, due to their high loss and non-linearity, in many applications such as phase shifters, oscillators, and tunable filters. The objective of this thesis is to develop novel MEMS varactors to improve the capacitance tuning ratio, linearity, and quality factor. Several novel varactor configurations are developed, analyzed, fabricated and tested. They are built by using standard MEMS fabrication processes, as well as monolithic integration techniques in CMOS technology. The first capacitor consists of two movable plates, loaded with a nitride layer that exhibits an analog continuous capacitance tuning ratio. To decrease the the parasitic capacitance, a trench in the silicon substrate under the capacitor is adopted. The use of an insulation dielectric layer on the bottom plate of the MEMS capacitor increases the capacitors’ tuning ratio. Experimental and theoretical results are presented for two versions of the proposed capacitor with different capacitance values. The measured capacitance tuning ratio is 280% at 1 GHz. The proposed MEMS vararctor is built using the MetalMUMPs process. The second, third, and fourth capacitors have additional beams that are called carrier beams. The use of the carrier beams makes it possible to obtain an equivalent nonlinear spring constant, which increases the capacitors’ analog continuous tuning ratio. A lumped element model and a continuous model of the proposed variable capacitors are developed. The continuous model is simulated by commercial software. A detailed analysis for the steady state of the capacitors is presented. The measured capacitance tuning ratios of these three capacitors are 410%, 400% and 470%, respectively at 1 GHz. Also, the selfresonance frequency is measured and found to exceed 11 GHz. The proposed MEMS variable capacitors are built by the PolyMUMPs process. The fifth novel parallel-plate MEMS varactor has thin-film vertical comb actuators as its driver. Such an actuator can vertically displace both plates of the parallel-plate capacitor. By making use of the fringing field, this actuator exhibits linear displacement behavior, caused by the induced electrostatic force of the actuator’s electrodes. The proposed capacitor has a low parasitic capacitance and linear deflection due to the mechanically connected and electrically isolated actuators to the capacitor’s parallel-plates. The measured tuning capacitance ratio is 7:1 (600%) at 1 GHz. The fabricated MEMS varactor exhibits a self resonance frequency of 9 GHz and built by MetalMUMPs process. The sixth parallel-plate MEMS varactor exhibits a linear response and high tuning capacitance ratio. The capacitor employs the residual stress of the chosen bi-layer, and the non-linear spring constants from the suspended cantilevers to obtain a non-linear restoring force that compensates for the nonlinear electrostatic force induced between the top and bottom plates. Two existing techniques are used to widen the tuning range of the proposed capacitor. The first technique is to decrease the parasitic capacitance by etching the lossy substrate under the capacitor’s plates. The second technique is employed to increase the capacitance density, where the areas between the top and bottom plates overlap, by applying a thin film of dielectric material, deposited by the atomic layer deposition (ALD) technique. The measured linear continuous tuning ratio for the proposed capacitor, built in the PolyMUMPs process, is 5:1 (400%). The seventh and eighth MEMS variable capacitors have plates that curl up. These capacitors are built in 0.35 μm CMOS technology from the interconnect metallization layers. The plates of the presented capacitors are intentionally curled upward to control the tuning performance. A newly developed maskless post-processing technique that is appropriate for MEMS/CMOS circuits is proposed. it consists of dry and wet etching steps, developed to integrate the proposed MEMS varactors in CMOS technology. Mechanically, the capacitors are simulated by the finite element method in ANSYS, and the results are compared with the measured results. The seventh capacitor is a tri-state structure that exhibits a measured tuning range of 460% at 1 GHz with a flat capacitance response that is superior to that of conventional digital capacitors. The proposed capacitor is simulated in HFSS and the extracted capacitance is compared with the measured capacitance over a frequency range of 1 GHz to 5 GHz. The eighth capacitor is an analog continuous structure that demonstrates a measured continuous tuning range of 115% at 1 GHz with no pull-in. The measured quality factor for both CMOSbased capacitors is more than 300 at 1.5 GHz. The proposed curled-plate capacitors have a small area and can be realized to build a System-on-Chip (SoC). Finally, a tunable band pass filter that utilizes the MEMS variable capacitors in 0.18 μm CMOS technology from TSMC is designed, modeled and fabricated.

Micro-Electro-Mechanical Systems (MEMS) varactors have the potential to replace conventional varactor diodes, due to their high loss and non-linearity, in many applications such as phase shifters, oscillators, and tunable filters. The objective of this thesis is to develop novel MEMS varactors to improve the capacitance tuning ratio, linearity, and quality factor. Several novel varactor configurations are developed, analyzed, fabricated and tested. They are built by using standard MEMS fabrication processes, as well as monolithic integration techniques in CMOS technology. The first capacitor consists of two movable plates, loaded with a nitride layer that exhibits an analog continuous capacitance tuning ratio. To decrease the the parasitic capacitance, a trench in the silicon substrate under the capacitor is adopted. The use of an insulation dielectric layer on the bottom plate of the MEMS capacitor increases the capacitors’ tuning ratio. Experimental and theoretical results are presented for two versions of the proposed capacitor with different capacitance values. The measured capacitance tuning ratio is 280% at 1 GHz. The proposed MEMS vararctor is built using the MetalMUMPs process. The second, third, and fourth capacitors have additional beams that are called carrier beams. The use of the carrier beams makes it possible to obtain an equivalent nonlinear spring constant, which increases the capacitors’ analog continuous tuning ratio. A lumped element model and a continuous model of the proposed variable capacitors are developed. The continuous model is simulated by commercial software. A detailed analysis for the steady state of the capacitors is presented. The measured capacitance tuning ratios of these three capacitors are 410%, 400% and 470%, respectively at 1 GHz. Also, the selfresonance frequency is measured and found to exceed 11 GHz. The proposed MEMS variable capacitors are built by the PolyMUMPs process. The fifth novel parallel-plate MEMS varactor has thin-film vertical comb actuators as its driver. Such an actuator can vertically displace both plates of the parallel-plate capacitor. By making use of the fringing field, this actuator exhibits linear displacement behavior, caused by the induced electrostatic force of the actuator’s electrodes. The proposed capacitor has a low parasitic capacitance and linear deflection due to the mechanically connected and electrically isolated actuators to the capacitor’s parallel-plates. The measured tuning capacitance ratio is 7:1 (600%) at 1 GHz. The fabricated MEMS varactor exhibits a self resonance frequency of 9 GHz and built by MetalMUMPs process. The sixth parallel-plate MEMS varactor exhibits a linear response and high tuning capacitance ratio. The capacitor employs the residual stress of the chosen bi-layer, and the non-linear spring constants from the suspended cantilevers to obtain a non-linear restoring force that compensates for the nonlinear electrostatic force induced between the top and bottom plates. Two existing techniques are used to widen the tuning range of the proposed capacitor. The first technique is to decrease the parasitic capacitance by etching the lossy substrate under the capacitor’s plates. The second technique is employed to increase the capacitance density, where the areas between the top and bottom plates overlap, by applying a thin film of dielectric material, deposited by the atomic layer deposition (ALD) technique. The measured linear continuous tuning ratio for the proposed capacitor, built in the PolyMUMPs process, is 5:1 (400%). The seventh and eighth MEMS variable capacitors have plates that curl up. These capacitors are built in 0.35 μm CMOS technology from the interconnect metallization layers. The plates of the presented capacitors are intentionally curled upward to control the tuning performance. A newly developed maskless post-processing technique that is appropriate for MEMS/CMOS circuits is proposed. it consists of dry and wet etching steps, developed to integrate the proposed MEMS varactors in CMOS technology. Mechanically, the capacitors are simulated by the finite element method in ANSYS, and the results are compared with the measured results. The seventh capacitor is a tri-state structure that exhibits a measured tuning range of 460% at 1 GHz with a flat capacitance response that is superior to that of conventional digital capacitors. The proposed capacitor is simulated in HFSS and the extracted capacitance is compared with the measured capacitance over a frequency range of 1 GHz to 5 GHz. The eighth capacitor is an analog continuous structure that demonstrates a measured continuous tuning range of 115% at 1 GHz with no pull-in. The measured quality factor for both CMOSbased capacitors is more than 300 at 1.5 GHz. The proposed curled-plate capacitors have a small area and can be realized to build a System-on-Chip (SoC). Finally, a tunable band pass filter that utilizes the MEMS variable capacitors in 0.18 μm CMOS technology from TSMC is designed, modeled and fabricated.

Varactors form an important part of many communication circuits. They are utilized in oscillators, tunable matching networks, tunable filters and phase-shifters. This thesis deals with the design, analysis, characterization and applications of a novel MEMS varactor. Lower actuation voltage and higher dynamic range are the two important issues widely addressed in the study of MEMS varactors. The pull-in instability, due to which only 33% of the gap between plates could be covered smoothly, greatly reduces useful dynamic range of MEMS varactors. We propose a torsional MEMS varactor that exploits “displacement amplification” whereby pull-in is overcome and wide dynamic range is achieved. The torsion beam in the device undergoes torsion as well as bending. Behavior of the device has been analyzed through torque and force balance. Based on the torque balance and the force balance expressions, theoretical limits of torsion angle and bending for stable operation have been derived. Torsional MEMS varactors and its variants are fabricated through a commercial fabrication process (polyMUMPS) and extensive characterization has been carried out. Capacitance-voltage characteristics show a maximum dynamic range of 1:16 with parasitic capacitance subtracted out from the capacitance values. A bidirectional torsional varactor, in which the top AC plate moves not only towards bottom plate but also away from bottom plate, is also tested. The bottom AC plate is isolated from low resistivity substrate with a thin nitride layer. This gives rise to large parasitic capacitances at higher frequencies. So to avoid this, a varactor with both AC plates suspended in air is designed and fabricated. A dynamic range of 1:8 including parasitic capacitances has been achieved. Self-actuation is studied on fabricated structures and a torsional varactor that overcomes self-actuation has been proposed. Hysteresis behavior of the torsional varactor is analyzed for different AC signals across the varactor plates. Effects of residual stress on C-V characteristics are studied and advantages and disadvantages of residual stress on device performance are discussed. The torsional varactors have been cycled between Cmax and Cmin for 36 hours continuously without any failure. High-frequency characteristics of torsional varactors are analyzed through measurements on one-port and two port configurations. Measurements are done on polyMUMPS devices to study the capacitance variation with voltage, quality factor (Q) and capacitance variation with frequency. Effects of substrate are de-embedded from the device and characteristics of device are studied. An analog phase shifter based on torsional varactor proposed and analyzed through HFSS simulations. Very high tuning range can be achieved with a LC-VCO based on torsional varactors. A LC VCO with the torsional varactor as a capacitor in LC tank is designed. The torsional varactor and IC are fabricated separately and are integrated through wire bonding. Bond-wires are used as inductors.

The focus of this work involves optical and RF (radio frequency) applications of novel microactuation and self-assembly techniques in MEMS (Microelectromechanical systems). The scaling of physical forces into the micro domain is favorably used to design several types of actuators that can provide large forces and large static displacements at low operation voltages. A self-assembly method based on thermally induced localized plastic deformation of microstructures has been developed to obtain truly three-dimensional structures from a planar fabrication process. RF applications include variable discrete components such as capacitors and inductors as well as tunable coupling circuits. Optical applications include scanning micromirrors with large scan angles (>90 degrees), low operation voltages (<10 Volts), and multiple degrees of freedom. One and two-dimensional periodic structures with variable periods and orientations (with respect to an incident wave) are investigated as well, and analyzed using optical phased array concepts. Throughout the research, permanent tuning via plastic deformation and power-off latching techniques are used in order to demonstrate that the optical and RF devices can exhibit zero quiescent power consumption once their geometry is set.

The focus of this work involves optical and RF (radio frequency) applications of novel microactuation and self-assembly techniques in MEMS (Microelectromechanical systems). The scaling of physical forces into the micro domain is favorably used to design several types of actuators that can provide large forces and large static displacements at low operation voltages. A self-assembly method based on thermally induced localized plastic deformation of microstructures has been developed to obtain truly three-dimensional structures from a planar fabrication process. RF applications include variable discrete components such as capacitors and inductors as well as tunable coupling circuits. Optical applications include scanning micromirrors with large scan angles (>90 degrees), low operation voltages (<10 Volts), and multiple degrees of freedom. One and two-dimensional periodic structures with variable periods and orientations (with respect to an incident wave) are investigated as well, and analyzed using optical phased array concepts. Throughout the research, permanent tuning via plastic deformation and power-off latching techniques are used in order to demonstrate that the optical and RF devices can exhibit zero quiescent power consumption once their geometry is set.

ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, Nevada / In pursuit to understanding the flight behavior and characterizing the stability of a flarestabilized projectile, an experiment was conducted to assess the robustness of an inertial sensor suite the size of a dime (17.5mm) by integrating to a telemetry system for recording. The system had to survive launch acceleration exceeding 25,000G’s. This is the beginning of an effort to reduce the size of telemetry systems and diagnostic devices for use in medium caliber munitions and smaller. A description of the telemetry system and subsystem will be presented along with the results.

This thesis presents the numerical and analytical study of the aerodynamic and heat transfer in laminar subsonic cascades along with the development of design guidelines and procedures to improve the design of microfabricated multistage radial turbines operating at low Reynolds number. Numerical analysis was performed on 24 cascade geometries using 2D computational fluid dynamics (CFD) for over 100 flow conditions for each cascade. Two dimensional correlations were extracted from CFD for profile and mixing losses, deviation and heat transfer. These correlations include Reynolds number and compressibility effects, and take into account incidence and various geometrical parameters (solidity, stagger, blade angles, thickness and mean-line distribution). Adaptation of losses to account for three dimensional effects and correlation for blockage were derived from analytical relationships. A turbomachinery simulation software based on mean-line analysis and conservation of rothalpy incorporating the developed correlations was programmed. The software can be adapted as for the physic it uses and the turbine configuration it analyses (axial, radial inward or outward, single or multi stage). The pressure profiles obtained from simulation were found to be in good agreement with experimental data for cold turbine tests. Design guidelines and charts are provided as well as cycle analysis considering microfabrication limitations. A considerable increase in stage isentropic efficiency compared to previous devices can result from the use of slender blades, lower solidity cascades and aspect ratios of 0.5, suggesting efficiencies as high as 85% for Re > 700. The study shows that higher power density and multistage matching can be achieved through the radial outward configuration. Two designs are presented, a single stage turbine for the next generation of microturbopump prototype and a turbine configuration with four rotors and 10 stages for closed Rankine cycle providing 50.7 W of net mechanical power.

Le domaine des MEMS (Micro-Electro-Mechanical Systems) est en pleine expansion, et plusieurs types de dispositifs requièrent des solutions d'isolation thermique efficace. Les solutions actuelles ne sont soit pas assez performantes, ou alors limitent les procédés de fabrication. Il existe donc un besoin pour une solution d'isolation thermique efficace et compatible avec les techniques actuelles de microfabrication sur silicium.Le silicium poreux est un candidat de choix, puisque sa conductivité thermique est inférieure de deux à trois ordres de grandeur à celle du silicium cristallin massif. De plus, ce matériau est fabriqué à partir des gaufres de silicium couramment utilisées pour la fabrication des MEMS, ce qui le rend a priori compatible avec les procédés de microfabrication standards. Finalement, il est possible de contrôler la localisation des zones porosifiées, facilitant son intégration dans des dispositifs. La fabrication du silicium poreux nécessite par contre quelques équipements et procédés bien spécifiques. Ce mémoire présente le développement et la mise en oeuvre, à l'Université de Sherbrooke, des équipements et procédés indispensables à la porosification du silicium et son intégration dans les procédés de microfabrication. Les équipements et procédés ont été choisis en ciblant l'application d'isolation thermique dans les MEMS. Plus précisément, un banc de porosification du silicium complet a été installé, avec plusieurs cellules d'anodisation et un générateur contrôlable. Ensuite ce système a été testé et calibré, et les procédés de base ont été mis au point, à savoir la porosification en elle-même, le séchage du matériau et sa stabilisation structurale. Des méthodes de caractérisation de la porosité et la vitesse de porosification ont été également été implémentées. Deux types de masques, pour la porosification localisée, ont également été développées [i.e. développés] : le premier est formé d'une couche de Si[indice inférieur 3]N[indice inférieur 4] LPCVD (Low Pressure Chemical Vapour Deposition) et le deuxième d'une couche de Si[indice inférieur 3]N[indice inférieur 4] PECVD (Plasma Enhanced Chemical Vapour Deposition) et d'une couche d'or. Finalement, la photolithographie sur silicium poreux a été étudiée. Ainsi, une méthode de photolithographie à base de résine solide, sous forme de film, a été élaborée. Cette méthode constitue une alternative intéressante aux photorésines classiques, dont l'utilisation pose des problèmes de compatibilité avec le silicium poreux. Cette résine a été utilisée comme résine de soulèvement et masque de gravure plasma, et a donné de bons résultats, malgré quelques problèmes d'adhérence. Des essais préliminaires de gravure plasma ont également été menés et ont donné des résultats plutôt prometteurs, avec notamment un taux de gravure deux à trois fois supérieur à celui du silicium. Ainsi, à l'issue de ces travaux de maîtrise, les équipements et procédés nécessaires à la fabrication et l'intégration du silicium poreux dans les MEMS, pour les applications à moyenne température, ont été implémentées [i.e. implémentés].