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Articles 1 - 30 of 32
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A Mems Planar Fresnel Lens For Cmut Array, Shivani Nilesh Upadhyay
A Mems Planar Fresnel Lens For Cmut Array, Shivani Nilesh Upadhyay
Electronic Theses and Dissertations
This thesis presents a Microelectromechanical Systems (MEMS) planar Fresnel lens for use with a Capacitive Micromachined Ultrasonic Transducer (CMUT) array for high-resolution cardiac diagnostic imaging applications. The research exploited the excellent sound propagation and thermal properties of cross-linked silica aerogel, a nano-porous, nano-networked ultra-light-weight material, to design a planar thinfilm lens that can be easily microfabricated or integrated with a CMUT array. The designed lens, comprised of 32 various width concentric rings, was optimized to operate with a 256 element 6 MHz CMUT array. The 4 µm thick lens was designed to generate a 1.9 mm focal spot at a …
Investigating Mems Devices In Flow Conditions Relevant To Flow-Through Systems., Mohammad Shafquatul Islam
Investigating Mems Devices In Flow Conditions Relevant To Flow-Through Systems., Mohammad Shafquatul Islam
Electronic Theses and Dissertations
Advancements in microscale actuating technologies has substantially expanded the possibilities of interacting with the surrounding environment. Microstructures that deflect in response to mechanical forces are one of the largest application areas of microelectromechanical systems (MEMS). MEMS devices, functioning as sensors, actuators, and support structures, find applications in inertial sensors, pressure sensors, chemical sensors, and robotics, among others. Driven by the critical role of catalytic membrane reactors, this dissertation aims to evaluate enzyme activity on polymeric membranes and explore how fabrication methods from the field of Electrical and Computer Engineering (ECE) can incorporate sensing and actuation into these porous surfaces. Toward …
Modeling, Simulation And Control Of Microrobots For The Microfactory., Zhong Yang
Modeling, Simulation And Control Of Microrobots For The Microfactory., Zhong Yang
Electronic Theses and Dissertations
Future assembly technologies will involve higher levels of automation in order to satisfy increased microscale or nanoscale precision requirements. Traditionally, assembly using a top-down robotic approach has been well-studied and applied to the microelectronics and MEMS industries, but less so in nanotechnology. With the boom of nanotechnology since the 1990s, newly designed products with new materials, coatings, and nanoparticles are gradually entering everyone’s lives, while the industry has grown into a billion-dollar volume worldwide. Traditionally, nanotechnology products are assembled using bottom-up methods, such as self-assembly, rather than top-down robotic assembly. This is due to considerations of volume handling of large …
Designing A Flexible Framework For Developing Acoustic Array Systems, Charles Fulton Gilliland
Designing A Flexible Framework For Developing Acoustic Array Systems, Charles Fulton Gilliland
Electronic Theses and Dissertations
In recent years, research conducted by the Applied Acoustics group at the NationalCenter for Physical Acoustics has involved the use of microphone arrays to study the propagation of sound through outdoor environments. In such research, there is need for data acquisition systems which can be reconfigured in both hardware and software. This work is an effort to develop a modular acoustic data acquisition framework which can be configured to accommodate a wide variety of acoustic array applications. In hardware, the framework provides modularity with a generic mainboard which uses a common interface to collect data from application-specific microphone boards. In …
Surface-Functionalized Chemiresistive Films That Exploit H-Bonding, Cation-Pi, And Metal-Halide Interactions., Prasadanie Karunarathna Adhihetty
Surface-Functionalized Chemiresistive Films That Exploit H-Bonding, Cation-Pi, And Metal-Halide Interactions., Prasadanie Karunarathna Adhihetty
Electronic Theses and Dissertations
The development of gas sensors for detection of volatile organic compounds (VOCs) has been of interest in the sensing field for decades. To date, the use of metal nanoparticle-based chemiresistors for trace VOC detection, particularly gold nanoparticle-based sensors, is of great interest due to their high chemical stability, ease of synthesis, unique optical properties, large surface to volume ratio, and high level of conductivity. Much effort has been devoted towards gold monolayer protected clusters (Au MPCs) as chemiresistors to detect harmful VOCs. The present thesis documents the results of our efforts to exploit the advantages of functionalized Au MPCs chemiresistors …
Design Of A Regulated Micromachined Air-Sniffer Using Thermal Transpiration Effect For E-Nose Applications, Mukesh Arvind Raju
Design Of A Regulated Micromachined Air-Sniffer Using Thermal Transpiration Effect For E-Nose Applications, Mukesh Arvind Raju
Electronic Theses and Dissertations
Microfluidics artificial olfaction systems are used for plant disease diagnosis in the agricultural field. In an electronic nose, the sniffer draws the air towards an array of gas sensors that detect volatile organic compounds corresponding to diseased plants. The currently available electronic noses involve a mechanical pump of moving parts prone to friction losses, limiting large-scale application. In this work, a microchannel that works on thermal transpiration principle to control the airflow inside it is proposed and designed. It has the potential to be employed as a sniffer component for electronic noses, designed using microelectromechanical systems. COMSOL Multiphysics simulation software …
Design And Modeling Of Piezoelectric Micromachined Ultrasonic Transducer (Pmut) Using A Multi-User Mems Process For Medical Imaging, Jenitha Antony Balasingam
Design And Modeling Of Piezoelectric Micromachined Ultrasonic Transducer (Pmut) Using A Multi-User Mems Process For Medical Imaging, Jenitha Antony Balasingam
Electronic Theses and Dissertations
According to the Canadian Cancer Society, 2020, “1 in 8 women will be affected by breast cancer and 1 in 33 will die from it.” There has been a decline in breast cancer causalities due to the early detection using advanced imaging technologies. This signifies the importance of early detection of breast cancer that increases the survival rate and treatment options for the patients. One of the platforms which are aiding the early detection is Microelectromechanical Systems (MEMS)-base imaging system. In this thesis, a Piezoelectric Micromachined Ultrasonic Transducer (PMUT) is proposed to work at lower frequency ranges for higher penetration …
Fabrication Of Silicon Microneedles For Dermal Interstitial Fluid Extraction In Human Subjects, Caleb A. Berry
Fabrication Of Silicon Microneedles For Dermal Interstitial Fluid Extraction In Human Subjects, Caleb A. Berry
Electronic Theses and Dissertations
The goal of this project is to design and develop a fabrication process for silicon microneedle arrays to extract dermal interstitial fluid (ISF) from human skin. ISF is a cell- free, living tissue medium that is known to contain many of the same, clinical biomarkers of general health, stress response and immune status as in blood. However, a significant barrier to adoption of ISF as a diagnostic matrix is the lack of a rapid, minimally invasive method of access and collection for analysis. Microfabricated chips containing arrays of microneedles that can rapidly and painlessly access and collect dermal ISF for …
Developing Highly Symmetric Microelectromechanical Systems (Mems) Based Butterfly Gyroscopes, Nabeel Ahmad Khan
Developing Highly Symmetric Microelectromechanical Systems (Mems) Based Butterfly Gyroscopes, Nabeel Ahmad Khan
Electronic Theses and Dissertations
Microelectromechanical systems (MEMS) is the technology combining electrical components with mechanical systems at a micro scale. The combination of these two technologies allowed devices to interact with each other and build complex structures. System on the chips are built with components such as masses, electrodes, anchors, actuators and detectors. Reducing the size, weight, energy usage and cost is key while maintaining the sensors integrity. Sensitivity is an important factor when evaluating a gyroscope’s performance. This research presents beam modeling techniques for maximizing mechanical sensitivity of the butterfly resonator for gyroscopic applications. It investigates the geometric aspects of synchronizing beam that …
Microrobots For Wafer Scale Microfactory: Design Fabrication Integration And Control., Ruoshi Zhang
Microrobots For Wafer Scale Microfactory: Design Fabrication Integration And Control., Ruoshi Zhang
Electronic Theses and Dissertations
Future assembly technologies will involve higher automation levels, in order to satisfy increased micro scale or nano scale precision requirements. Traditionally, assembly using a top-down robotic approach has been well-studied and applied to micro-electronics and MEMS industries, but less so in nanotechnology. With the bloom of nanotechnology ever since the 1990s, newly designed products with new materials, coatings and nanoparticles are gradually entering everyone’s life, while the industry has grown into a billion-dollar volume worldwide. Traditionally, nanotechnology products are assembled using bottom-up methods, such as self-assembly, rather than with top-down robotic assembly. This is due to considerations of volume handling …
A Miniaturized Chemical Vapor Detector Using Mems Flexible Platform, Haleh Nazemi
A Miniaturized Chemical Vapor Detector Using Mems Flexible Platform, Haleh Nazemi
Electronic Theses and Dissertations
According to the Canadian Cancer Society, lung cancer is the one of the leading causes of cancer death. It has been shown that cancer survival chance depends on factors including the availability of early detection and diagnostic tools such as miniaturized and sensitive gas sensor. This can detect the released volatiles in addition to be implementable in portable electronics, which decisively improves the patient’s survival rate. Therefore, in this thesis and in an effort to develop high-sensitive and miniaturized gas sensor, a microelectromechanical systems (MEMS) platform is utilized. In this work, a sensitive gas sensor is proposed by employing capacitive …
Exploration Of Radiation Damage Mechanism In Mems Devices., Pranoy Deb Shuvra
Exploration Of Radiation Damage Mechanism In Mems Devices., Pranoy Deb Shuvra
Electronic Theses and Dissertations
We explored UV, X-ray and proton radiation damage mechanisms in MEMS resonators. T-shaped MEMS resonators of different dimensions were used to investigate the effect of radiation. Radiation damage is observed in the form of resistance and resonance frequency shift of the device. The resistance change indicates a change in free carrier concentration and mobility, while the resonance frequency change indicates a change in mass and/or elastic constant. For 255nm UV radiation, we observed a persistent photoconductivity that lasts for about 60 hours after radiation is turned off. The resonance frequency also decreases 40-90 ppm during irradiation and slowly recovers at …
Piezoelectric Bistable Buckled Beam Energy Harvester., Brian Edward Allgeier
Piezoelectric Bistable Buckled Beam Energy Harvester., Brian Edward Allgeier
Electronic Theses and Dissertations
A novel energy harvesting device design is presented to be created via microfabrication techniques. Such devices have countless applications for powering low-current electrical devices, especially wireless sensors or transmitters. This micro-electromechanical system (MEMS) design utilizes the piezoelectric response of a bistable buckled beam to gather electrical energy via ambient vibrations. While many traditional piezoelectric energy harvesters (PEH) consist of simple cantilever beam geometries, this nonlinear design utilizes inertial effects of torsional lever arms to actuate a central buckled beam to snap between its two stable states; such an abrupt strain on the piezoelectric beam potentially produces a significantly increased electrical …
Applications Of Polarized Metallic Nanostructures., Jasmin Beharic
Applications Of Polarized Metallic Nanostructures., Jasmin Beharic
Electronic Theses and Dissertations
Gold nanostructures exhibit technologically useful properties when they are polarized in an electric field. In two projects we explore instances where the polarized metal can be used in real world applications. The first project involves gold nanoparticles (GNP) for use in light actuated microelectromechanical systems (MEMS) applications. Although the GNPs were originally designed for volumetric heating in biomedical applications, we treat them as a thin film coating, opening the door for these particles to be used in MEMS applications. This work characterizes the thermal properties of gold nanoparticles on surfaces for spatially-targeted thermal actuation in MEMS systems. The second project …
Energy Harvesting For Iot Sensors, Parvathi Shenoy Kasargod
Energy Harvesting For Iot Sensors, Parvathi Shenoy Kasargod
Electronic Theses and Dissertations
The growing need for alternative energy sources for sensors and portable devices has led to many energy-harvesting solutions. As the technology scales down and the supply voltage drops, the complexity of designing energy harvesting circuits increases. In this work, a vibrational energy harvester using Microelectromechanical systems (MEMS) based switches is proposed. The MEMS switches are used to design a high efficiency rectifier instead of diodes. The voltage drop across diodes in conventional rectifiers reduces the efficiency of energy harvesters. The operation of the MEMS switches in the proposed rectifier is similar to the commutators in DC motor where alternating current …
Strategies And Techniques For Fabricating Mems Bistable Thermal Actuators., Dilan Ratnayake
Strategies And Techniques For Fabricating Mems Bistable Thermal Actuators., Dilan Ratnayake
Electronic Theses and Dissertations
Bistable elements are beginning to appear in the field of MEMS as they allow engineers to design sensors and actuators which require no electrical power and possess mechanical memory. This research focuses on the development of novel strategies and techniques for fabricating MEMS bistable structures to serve as no electrical power thermal actuators. Two parallel strategies were explored for the design and fabrication of the critical bistable element. Both strategies involved an extensive material study on candidate thin film materials to determine their temperature coefficient of expansion and as-deposited internal stress properties. Materials investigated included titanium tungsten, Invar, silicon nitride …
A Resonant Based Test Methodology For Capacitive Mems, Ali Dianat
A Resonant Based Test Methodology For Capacitive Mems, Ali Dianat
Electronic Theses and Dissertations
This work presents a test method for capacitive Micro-Electro-Mechanical Systems (MEMS). A major class of MEMS sensors operate based on the principle of capacitance variation.The proposed test method in this work utilizes a resonant circuit to detect structural defects of capacitive MEMS sensors. It is shown that a small variation of MEMS capacitance due to a defect alters the resonance frequency considerably. It is also shown that the variation of the output amplitude can be observed for fault detection if an inductor with a high quality factor is employed in the test circuit. Mathematical approach is taken and verified to …
A Microreactor Approach For Chemoselective Capture And Analysis Of Carbonyl Compounds In Air And Exhaled Breath., Mingxiao Li
A Microreactor Approach For Chemoselective Capture And Analysis Of Carbonyl Compounds In Air And Exhaled Breath., Mingxiao Li
Electronic Theses and Dissertations
Detection of volatile organic compounds (VOCs) at trace level (parts per billion volume (ppbv) to parts per trillion (pptv)) has become an important research area because of demanding applications in homeland security, environmental monitoring, and noninvasive diagnosis of diseases. The analysis of trace VOCs challenges existing analytical instruments because their concentrations are beyond current instrument limits of detection. In this dissertation, we have investigated an innovative microreactor that is suitable for quantitative analysis of volatile carbonyl compounds in ambient air as well as in human exhaled breath. The approach is based on microreactor chips fabricated from four inch silicon wafers. …
An Improved Thin-Film Microelectrode Array And Signal Conditioning Board For Measuring Cardiac Surface Potentials., Christopher Hayward Osborne
An Improved Thin-Film Microelectrode Array And Signal Conditioning Board For Measuring Cardiac Surface Potentials., Christopher Hayward Osborne
Electronic Theses and Dissertations
The work outlined in this thesis expanded on previous work to improve a thin-film microfabricated electrode array intended for cardiac electrophysiology studies. A thin layer of silver was added in between titanium and platinum electrical trace layers to reduce electrode resistance. A 200 nm layer of silver decreased electrode resistance by an order of magnitude. In addition, a new high quality signal conditioning board was developed using precision operational amplifiers from Texas Instruments. Both new sensor and board design were verified together through in vivo studies using rabbit, goat, and dog hearts.
Mechanical Characterization Of Mems Bi-Stable Buckled Diaphragms., Isaac James Phelps
Mechanical Characterization Of Mems Bi-Stable Buckled Diaphragms., Isaac James Phelps
Electronic Theses and Dissertations
Bi-stable buckled MEMS (micro-electromechanical systems) diaphragms have a myriad of uses in the MEMS field for their large out-of-plane deflections. Buckling is a phenomenon brought upon by a compressive stress. Diaphragms are large aspect ratio, circular structures similar to membranes, where the thickness of the diaphragm is much smaller than its diameter. Diaphragms differ from membranes by the amount of bending stiffness. Membranes have negligible bending stiffness and are a common structure analyzed in mechanics of materials, whereas diaphragms have much larger stiffness. Diaphragms were created in the cleanroom by thermally growing silicon dioxide on a silicon wafer. A structural …
A 5 Meter Range Non-Planar Cmut Array For Automotive Collision Avoidance, Jonathan Hernandez Aguirre
A 5 Meter Range Non-Planar Cmut Array For Automotive Collision Avoidance, Jonathan Hernandez Aguirre
Electronic Theses and Dissertations
A discretized hyperbolic paraboloid geometry capacitive micromachined ultrasonic transducer (CMUT) array has been designed and fabricated for automotive collision avoidance. The array is designed to operate at 40 kHz, beamwidth of 40° with a maximum sidelobe intensity of -10dB. An SOI based fabrication technology has been used for the 5x5 array with 5 sensing surfaces along each x and y axis and 7 elevation levels. An assembly and packaging technique has been developed to realize the non-planar geometry in a PGA-68 package. A highly accurate mathematical method has been presented for analytical characterization of capacitive micromachined ultrasonic transducers (CMUTs) built …
Incorporating Nanomaterials With Mems Devices., Evgeniya V. Moiseeva 1980-
Incorporating Nanomaterials With Mems Devices., Evgeniya V. Moiseeva 1980-
Electronic Theses and Dissertations
This dissertation demonstrates an elegant method, known as 'micro-origami' or strain architecture to design and fabricate three-dimensional MEMS structures which are assembled using actuation of a metal-oxide bilayer with conventional planar lithography. Folding allows creating complex, robust, three-dimensional shapes from two-dimensional material simply by choosing folds in the right order and orientation, small disturbances of the initial shape may also be used to produce different final shapes. These are referred to as "pop-up structures" in this work. The scope of this work presented the deposition of colloidal gold nanoparticles (GNPs) into conformal thin films using a microstenciling technique. Results illustrated …
High Frequency Thermally Actuated Single Crystalline Silicon Micromechanical Resonators With Piezoresistive Readout, Amir Rahafrooz
High Frequency Thermally Actuated Single Crystalline Silicon Micromechanical Resonators With Piezoresistive Readout, Amir Rahafrooz
Electronic Theses and Dissertations
Over the past decades there has been a great deal of research on developing high frequency micromechanical resonators. As the two most common and conventional MEMS resonators, piezoelectric and electrostatic resonators have been at the center of attention despite having some drawbacks. Piezoelectric resonators provide low impedances that make them compatible with other low impedance electronic components, however they have low quality factors and complicated fabrication processes. In case of electrostatic resonators, they have higher quality factors but the need for smaller transductions gaps complicates their fabrication process and causes squeezed film damping in Air. In addition, the operation of …
Label-Free Biochemical Recognition Using Mems Resonators For Microarray Technology, Babak Tousifar
Label-Free Biochemical Recognition Using Mems Resonators For Microarray Technology, Babak Tousifar
Electronic Theses and Dissertations
Highly sensitive biosensors capable of detecting and characterizing smallest quantities of cellular and molecular targets are needed in pharmaceutical and medical diagnostics industries. In this work, the importance of biological target recognition specifically proteins through microarray technologies has been discussed and the most successful tools and techniques have been studied. Moreover, a thermally actuated Micro Electro-Mechanical Systems (MEMS) resonator has been demonstrated and fabricated in this work as an accurate, reliable and low cost biotechnology tool. As a proof of concept, amine to epoxide coupling of octadecylamine to functionalized silicon dioxide surface have been shown through resonator frequency monitoring. The …
Mems Transducer For Hearing Aid Device, Houwen Tang
Mems Transducer For Hearing Aid Device, Houwen Tang
Electronic Theses and Dissertations
A study of implantable middle ear MEMS piezoelectric transducer for hearing aids was developed. The physical vibration deflection at the tip of the transducer is simulated using finite element method. Further, a study of thermoelastic damping effect of four designed MEMS mirrors used as resonators is presented. An optical measurement system based on Mach-Zehnder interferometer is
Bio-Mechanically Driven Mems Power Generator For Implantable Medical Devices., Jose Martinez-Quijada
Bio-Mechanically Driven Mems Power Generator For Implantable Medical Devices., Jose Martinez-Quijada
Electronic Theses and Dissertations
No abstract provided.
A Mems Non-Planar Ultrasonic Microarray., Matthew Meloche
A Mems Non-Planar Ultrasonic Microarray., Matthew Meloche
Electronic Theses and Dissertations
No abstract provided.
Novel Conceptual Design And Anlysis Of Polymer Derived Ceramic Mems Sensors For Gas Turbine Environment, Narasimha Nagaiah
Novel Conceptual Design And Anlysis Of Polymer Derived Ceramic Mems Sensors For Gas Turbine Environment, Narasimha Nagaiah
Electronic Theses and Dissertations
Technical challenges for developing micro sensors for Ultra High Temperature and turbine applications lie in that the sensors have to survive extremely harsh working conditions that exist when converting fuel to energy. These conditions include high temperatures (500-1500°C), elevated pressures (200-400 psi), pressure oscillations, corrosive environments (oxidizing conditions, gaseous alkali, and water vapors), surface coating or fouling, and high particulate loading. Several technologies are currently underdeveloped for measuring these parameters in turbine engines. One of them is an optical-based non-contact technology. However, these nondirective measuring technologies lack the necessary accuracy, at least at present state. An alternative way to measure …
A Mems Sonoluminescent Ultrasonic Sensor., Andrew Tam
A Mems Sonoluminescent Ultrasonic Sensor., Andrew Tam
Electronic Theses and Dissertations
No abstract provided.
Design And Development Of A Mems-Based Capacitive Bending Strain Sensor And A Biocompatible Housing For A Telemetric Strain Monitoring System., Julia Marie Weyer Aebersold 1969-
Design And Development Of A Mems-Based Capacitive Bending Strain Sensor And A Biocompatible Housing For A Telemetric Strain Monitoring System., Julia Marie Weyer Aebersold 1969-
Electronic Theses and Dissertations
Lumbar arthrodesis or spinal fusion is usually performed to relieve back pain and regain functionality from ruptured discs, disc degenerative disease, trauma and scoliosis. Metal rods are often fixed to the spine with screws or hooks, while fusion develops on the affected vertebrae. Fusion is determined by visual examination of radiographic images (X-ray), computed tomography (CT) scans or magnetic resonance imaging (MRI), yet these inspection procedures are subjective methods of review. They do not objectively confirm the presence of spinal fusion, which can lead to exploratory surgery to determine if fusion has occurred. Therefore, a need has arisen to develop …