Monitoring bio-electric events is a common procedure, which provides medical data required in clinical and research applications. Electrophysiological measurements are applied in diagnosis as well as evaluation of the performance of different body organs and systems, e. g. the heart, muscles and the nervous system. Furthermore, it is staple feature in operation rooms and extensive care units. The performance of the recording system is affected by the tools and instrumentation used and the bio-electrode is a key-player in electrophysiology, hence, the improvements in the electrode recording technique will be directly reflected in the system?s performance in terms of the signal quality, recording duration as well as patient comfort. In this thesis, a design methodology for micro-spike array dry bio-electrodes is introduced. <br /><br /> The purpose of this methodology is to meet the design specifications for portable long-term EEG recording and optimize the electrical performance of the electrodes by maximizing the electrode-skin contact surface area, while fulfilling design constraints including mechanical, physiological and economical limitations. This was followed by proposing a low cost fabrication technique to implement the electrodes. The proposed electrode design has a potential impact in enhancing the performance of the current recording systems, and also suits portable monitoring and long term recording devices. The design process was aided by using a software design and optimization tool, which was specifically created for this application. <br /><br /> The application conditions added challenges to the electrode design in order to meet the required performance requirements. On the other hand, the required design specifications are not fulfilled in the current electrode technologies which are designed and customized only for short term clinical recordings. <br /><br /> The electrode theory of application was verified using an experimental setup for an electrochemical cell, but the overall performance including measuring the electrode impedance is awaiting a clinical trial.

Magnetically levitated microrobotic systems have shown a great deal of promise for micromanipulation tasks. A new large-gap magnetic suspension system has recently been developed at the University of Waterloo in order to develop microrobotic systems for various applications. In order to achieve motion with the system, a model is needed in order to facilitate the design of various aspects of the system, such as the microrobot and the controller. In order to derive equations of motion for the system attempts were made to characterize the force produced by the magnetic drive unit in terms of a simple analytical equation. The force produced by the magnetic drive unit was estimated with the aid of a finite element model. The derived equations were able to predict the general trend of the force curves, and with sufficient parameter tweaking the error between the force estimated by the finite element model and the force estimated by the analytical equation could be minimized. System models describing the motion of the system in the horizontal and vertical directions are identified and compared to the actual system response. The vertical position response is identified through a least squares parameter estimate of the closed loop response combined with a partial reconstruction of the root locus diagram, with the model structure based on the known dynamics of a simplified form of magnetic levitation. This model was able to provide a reasonable prediction of the system response for a variety of PID controllers under a variety of input conditions. The horizontal models are identified using a least-squares parameter estimate of the open loop characteristics of the system. The horizontal models are able to provide a reasonable prediction of the system response under PD and PID control. Full spatial motion of a microrobot prototype is demonstrated over a working range of 20x22x30 mm³, with PID controller parameters and reference trajectories adjusted to minimize disturbances. The RMS error at steady state is on the order of 0. 020 mm for vertical positioning and 0. 008 mm for horizontal positioning. A linear quadratic regulator implemented for vertical position control was able to reduce the vertical position RMS error to 0. 014 mm.

This thesis focuses on the design of a versatile, portable, and cost-effective fluorescence detection system for LOC devices. Components that are widely available are used, such as LEDs for excitation and a microcontroller for processing. In addition, a photoresistor is tested for the feasibility of being used as a fluorescence detector, instead of the more commonly used photomultiplier tubes. The device also focuses on upgradeability and versatility, meaning that most of the major components can be replaced as long as power requirements remain unaffected. This allows for future additions to the device once they are available, as well as giving the user the power to choose which add-ons are needed since not all users may have the same requirements. The performance of the device after testing with fluorescein dyes and stained yeast cells indicate that it is capable of executing simple tasks, such as determining the presence and concentration of an analyte if given a sufficient amount. It also provided similar readings to commercial fluorescence analysers, which proves its ability to function as a fluorescence detector device. The thesis also proposes a MEMS diffraction grating that can be used for wavelength tuning. By being able to selectively measure across a range of wavelengths, the capability of the device is increased. Examples include being able to detect multiple fluorescent emissions, which will complement the multicoloured excitation LED nicely. In addition, the device will not be limited to a predetermined set of filters. This effectively allows more fluorescent dyes to be used with the device since any wavelength in the visible range can be selectively filtered for. Simulations of the proposed diffraction grating were performed in ANSYS to confirm the validity of the calculated values. In addition, tests were performed on a slide fabricated with diffraction gratings using values as close to the calculated values as possible. All of the results indicate that there is great promise in the proposed diffraction grating design and that it should be further investigated.

In today’s communication devices, the need for high performance inductors is increasing as they are extensively used in RF integrated circuits (RFICs). This need is even more pronounced for variable inductors as they are widely required in tunable filters, voltage controlled amplifiers (VCO) and low noise amplifiers (LNA). For RFICs, the main tuning elements are solid state varactors that are used in conjunction with invariable inductors. However, they have limited linearity, high resistive losses, and low self resonant frequencies. This emphasizes the need for developing another tuning element that can be fabricated monolithically with ICs and can offer high range of tuning. Due to the ease of CMOS integration and low cost silicon based IC fabrication, the inductors currently used are a major source of energy loss, therefore driving the overall quality factor and performance of the chip down. During the last decade there has been an increase in research in RF MicroelectroMechanical Systems (RF MEMS) to develop high quality on chip tunable RF components. MEMS capacitors were initially proposed to substitute the existing varactors, however they can not be easily integrated on top of CMOS circuits. RF MEMS variable inductors have recently attracted attention as a better alternative. The research presented here explores using porous anodic alumina (PAA) in CMOS and MEMS fabrication. Due to its low cost and low temperature processing, PAA is an excellent candidate for silicon system integration. At first, PAA is explored as an isolation layer between the inductor and the lossy silicon substrate. Simulations show that although the dielectric constant of the PAA is tunable, the stress produced by the required thicker layers is problematic. Nevertheless, the use of PAA as a MEMS material shows much more promise. Tunable RF MEMS inductors based on bimorph sandwich layer of aluminum PAA and aluminum are fabricated and tested. A tuning range of 31% is achieved for an inductance variation of 5.8 nH to 7.6 nH at 3 GHz. To further improve the Q, bimorph layers of gold and PAA are fabricated on Alumina substrates. A lower tuning range is produced; however the quality factor performance is greatly improved. A peak Q of over 30 with a demonstrated 3% tuning range is presented. Depending on the need for either high performance or tunability, two types of tunable RF MEMS inductors are presented. Although PAA shows promise as a mechanical material for MEMS, the processing parameters (mainly stress and loss tangent) need to be improved if used as an isolation layer. To our knowledge, this is the first time this material has been proposed and successfully used as a structural material for MEMS devices and CMOS processes.

The focus of this research is on the development of a novel multi-disciplinary design optimization scheme for micro-compliant devices. Topology optimization is a powerful tool that can address the need for a systematic method to design MEMS. It is expected that systematic design methods will make the design of micro devices transparent to the user and thus spur their use. Although topology optimization of MEMS devices with embedded actuation has received a great deal of attention among researchers recently, there is not a significant amount of literature available on the subject. The limited literature available addresses multi-physics topology optimization, which employs the homogenization method. However, the products of this method inherit the drawbacks of homogenized material discretization, including checkerboard pattern, gray-scale material and narrow flexural hinges in the optimum solution. In this thesis, a new topology optimization scheme is introduced that addresses the specific needs of MEMS domain. A new discretization approach with frame-ground structure is introduced. This approach offers significant conceptual and practical advantages to the compliant MEMS optimization problem, including compatibility with MEMS fabrication processes. The design spaces of compliant mechanisms are non-convex and it is critical to employ an algorithm capable of converging to the global optimum without the need to evaluate gradients of objective function. In this thesis, an efficient real-coded genetic algorithm is implemented, which shows a better repeatability and converges to very similar solutions in different runs. This new method of optimization facilitates the use of a coarse subdivision of the design domain rather than the homogenized material method, for the same resolution of shape definition. Therefore, the topology optimization scheme developed in this thesis significantly reduces the computational burden without compromising the sharpness of the shape definition. As the problem of compliant mechanism design is posed as a set of conflicting objectives, a well-posed multi-criteria objective function is introduced which avoids one objective dominating the solution. Moreover, the formulation is modified to incorporate electro-thermal boundaries and enables the optimization of the compliant mechanisms to transfer maximum motion or maximum force at the output. A number of design examples are used to demonstrate the ability of the procedure to generate non-intuitive topologies. Their performance is verified using ANSYS and compared with results from the homogenization method and designs reported in the available literature.

Uncooled microbolometers have attracted significant interest due to their small size, low cost and low power consumption. As the application range of microbolometers broadens, increasing the dynamic range becomes one of the main objectives of microbolometer research. Targeting this objective, tunable thermal conductance microbolometers have been proposed recently, in which the thermal conductance is tuned by electrostatic actuation. Being a new concept in the field, the current tunable thermal conductance microbolometers have significant potential for improvement in design and performance. In this thesis, an extensive analysis of tunable thermal conductance microbolometers is made, an analytical model is constructed for this purpose, and solutions are proposed to some potential problems such as in-use stiction and variation in spectral response. The current thermal conductance tuning mechanisms use the substrate for electrostatic actuation, which does not support pixel-by-pixel actuation. In this thesis, a new thermal conductance tuning mechanism is demonstrated, that enables pixel-by-pixel actuation by using the micromirror as an actuation terminal instead of the substrate. In addition, a stopper mechanism is used to decrease the risk of in-use stiction. With this new mechanism, the thermal conductance can be tuned by a factor of three at relatively low voltages, making it a promising thermal conductance tuning mechanism for adaptive infrared detectors. Effective estimation of the performance parameters of a tunable thermal conductance microbolometer in the design state requires an analytical model that combines the physics of infrared radiation detection and the thermal conductance tuning mechanisms. As a part of this research, an extensive analytical model is presented, which includes the electrostatic-structural modeling of the thermal conductance tuning mechanism, and electromagnetic and thermal modeling of the microbolometer. The accuracy of the thermal model is of significant importance as the operation of the tuning mechanism within the desired range should be verified in the design stage. A thermal model based on the solution of the microbolometer heat conduction equation is established, which is easily applicable to conventional and tunable thermal conductance microbolometers of various shapes. The constructed microbolometer model is validated by experiments and finite element model simulations. Furthermore, the effect of thermal conductance tuning on spectral response is analyzed. The present thermal conductance tuning mechanisms result in variations in spectral response, which is an undesired effect in many applications. As a solution, a new microbolometer architecture is proposed, in which the spectral response is not affected by thermal conductance. The microbolometer is designed using an analytical model and its performance is characterized by finite element model simulations. To realize the proposed design, a fabrication process flow is offered. It is shown that the proposed microbolometer exhibits high performance, tunable thermal conductance and constant spectral response.

On-chip characterization devices have been used to extract the Young’s modulus, average stress and stress gradient of polysilicon doped with phosphorus using thermal diffusion. Devices for extracting the Young’s modulus, average stress and stress gradients have been designed to work within the range of expected material property values. A customized fabrication process was developed and the devices were fabricated. Static and resonant tests were performed using clamped-clamped and cantilever beams in order to extract material properties. The experimental setup and detailed experimental results and analysis are outlined within. Several doping concentrations have been studied and it has been concluded that the Young’s modulus of polysilicon doped for 2 hours increases by approximately 50GPa and the average stress of polysilicon doped for 2.5 hours becomes more tensile by approximately 63 MPa. It has also been found that short doping times can introduce a large enough stress gradient to create a concave up curvature in free-standing structures. This work was performed in order to determine the usability of doping as a means to increase the sensitivity of temperature and pressure sensors for harsh environments. It has been concluded that doping is a promising technique and is worth studying further for this purpose.

Aeroacoustic emissions were identified as a primary concern in the public acceptance of wind turbines. A review of literature involving sound localization was undertaken and led to the design of two microphone arrays to identify acoustic sources. A small-scale array composed of 27 sensors was produced with the intention of improving the quality of sound measurements over those made by a single microphone in a small, closed-loop wind tunnel. A large-scale array containing 30 microphones was also implemented to allow for measurements of aeroacoustic emissions from airfoils and rotating wind turbines. To minimize cost and pursue alternative sensor technologies, microelectromechanical microphones were selected for the array sensors and assembled into the arrays on printed circuit boards. Characterization of the microphones was completed using a combination of calibration techniques, primarily in a plane wave tube. Array response to known sources was quantified by analyzing source maps with respect to source location accuracy, beamwidth, and root mean square error. Multiple sources and rotating sources were tested to assess array performance. Following validation with known sources, wind tunnel testing of a 600 watt wind turbine was performed at freestream speeds of 2.5 m/s, 3.5 m/s, 4.5 m/s, and to 5.5 m/s. Significant aeroacoustic emissions were noted from the turbine in the 4.5 m/s and 5.5 m/s cases, with an increase of up to 12 dB over background levels. Source maps from the 5.5 m/s tests revealed that the primary location of aeroacoustic emissions was near the outer radii of the rotor, but not at the tip, and generally moved radially outward with increasing frequency. The azimuthal location of the greatest sound pressure levels was typically found to be between 120º and 130º measured counterclockwise from the upward vertical, coinciding with the predicted location of greatest emissions provided by an analytical model based on dipole directivity and convective amplification. Analysis of the acoustic spectra, turbine operating characteristics, and previous literature suggested that the sound emissions emanated from the trailing edge of the blades.

In recent years, research efforts in the development of Micro Electro Mechanical Systems, (MEMS) including microactuators and micromanipulators, have attracted a great deal of attention. The development of microfabrication techniques has resulted in substantial progress in the miniaturization of devices such as electronic circuits. However, the research in MEMS still lags behind in terms of the development of reliable tools for post-fabrication processes and the precise and dexterous manipulation of individual micro size objects. Current micromanipulation mechanisms are prone to high costs, a large footprint, and poor dexterity and are labour intensive. To overcome such, the research in this thesis is focused on the utilization of microactuators in micromanipulation. Microactuators are compliant structures. They undergo substantial deflection during micromanipulation due to the considerable surface micro forces. Their dominance in governing micromanipulation is so compelling that their effects should be considered in designing microactuators and microsensors. In this thesis, the characterization of the surface micro forces and automated micromanipulation are investigated. An inexpensive experimental setup is proposed as a platform to replace Atomic Force Microscopy (AFM) for analyzing the force characterization of micro scale components. The relationship between the magnitudes of the surface micro forces and the parameters such as the velocity of the pushing process, relative humidity, temperature, hydrophilicity of the substrate, and surface area are empirically examined. In addition, a precision automated micromanipulation system is realized. A class of artificial neural networks (NN) is devised to estimate the unmodelled micro forces during the controlled pushing of micro size object along a desired path. Then, a nonlinear controller is developed for the controlled pushing of the micro objects to guarantee the stability of the closed loop system in the Lyapunov sense. To validate the performance of the proposed controller, an experimental setup is designed. The application of the proposed controller is extended to precisely push several micro objects, each with different characteristics in terms of the surface micro forces governing the manipulation process. The proposed adaptive controller is capable of learning to adjust its weights effectively when the surface micro forces change under varying conditions. By using the controller, a fully automated sequential positioning of three micro objects on a flat substrate is performed. The results are compared with those of the identical sequential pushing by using a conventional linear controller. The results suggest that artificial NNs are a promising tool for the design of adaptive controllers to accurately perform the automated manipulation of multiple objects in the microscopic scale for microassembly.

Multi-band and multi-mode radios are becoming prevalent and necessary in order to provide optimal data rates across a network with a diverse and spotty landscape of coverage areas (3G, HSPA, LTE, etc.). As the number of required bands and modes increases, the aggregate cost of discrete RF signal chains justi es the adoption of tunable solutions. Tunable fi lters are one of the pieces crucial to signal chain amalgamation. The main requirements for a tunable fi lter are high unloaded quality factor, wide tuning range, high tuning speed, high linearity, and small size. MEMS technology is the most promising in terms of tuning range, quality factor, linearity and size. In addition, a fi lter that maintains a constant passband bandwidth as the center frequency is tuned is preferred since the analog baseband processing circuitry tends to be tailored for a particular signal bandwidth. In this work, a novel design technique for tunable fi lters with controlled and predictable bandwidth variation is presented. The design technique is presented alongside an analysis and modeling method for predicting the final filter response during design optimization. The method is based on the well known coupling matrix model. In order to demonstrate the design and modeling technique, a novel coupling structure for stripline fi lters is presented that results in substantial improvements in coupling bandwidth variation over an octave tuning range when compared to combline and interdigitated coupled line fi lters. In order for a coupled resonator filter to produce an equal ripple Chebyshev response, each resonator of the fi lter must be tuned to precisely the same resonant frequency. Production tuned fi lters are routinely tuned in the lab and production environments by skilled technicians in order to compensate for manufacturing tolerances. However, integrated tunable filters cannot be tuned by traditional means since they are integrated into systems on circuit boards or inside front end modules. A fixed tuning table for all manufactured modules is inadequate since the required tuning accuracy exceeds the tolerance of the tuning elements. In this work, we develop tuning techniques for the automatic in-circuit tuning of tunable filters using scalar transmission measurement. The scalar transmission based techniques obviate the use of directional couplers. Techniques based on both swept and single frequency scalar transmission measurement are developed. The swept frequency technique, based on the Hilbert transform derived relative groupdelay, tunes both couplings and resonant frequencies while the single frequency technique only tunes the center frequency. High performance filters necessitate high resonator quality factors. Although fi lters are traditionally treated as passive devices, tunable fi lters need to be treated as active devices. Tuning elements invariably introduce non-linearities that limit the useful power handling of the tunable fi lter. RF MEMS devices have been a topic of intense research for many years for their promising characteristics of high quality factor and high power handling. Control and reliability issues have resulted in a shift from continuously tunable devices to discretely switched devices. However, fi lter tuning applications require fine resolution and therefore many bits for digital capacitor banks. An analog/digital hybrid tuning approach would enable the tuning range of a switched capacitor bank to be combined with the tuning resolution of an analog tunable capacitor. In this work, a device-level position control mechanism is proposed for piezoresistive feedback of device capacitance over the device's tuning range. It is shown that piezoresistve position control is ef ective at improving capacitance uncertainty in a CMOS integrated RF MEMS variable capacitor.