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Articles 1 - 30 of 128
Full-Text Articles in Engineering
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 …
Planar Element Alignment System, Benjamin E. Lavigna, Benny F. Cruz, Samuel Gierhan, Jacob Q. Henriksen
Planar Element Alignment System, Benjamin E. Lavigna, Benny F. Cruz, Samuel Gierhan, Jacob Q. Henriksen
Mechanical Engineering
Precise alignment to the micron level is a necessity for microfluidic/micromechanical devices to function as designed. Because of this, a micro-alignment device was commissioned by Professor Hans Mayer on behalf of the Cal Poly Microfluidics Laboratory. Prototype creation was bounded by a set of requirements including, ability to align PDMS & Silicon wafer halves to ± 10 microns, total process speed of three minutes, and total budget of $3000. Some major design hurdles included an ability to verify alignment, possible non-planar alignment pieces, and an inability to contact any point on the face of the alignment pieces after bonding treatment. …
Novel Test Fixture For Characterizing Mems Switch Microcontact Reliability And Performance, Protap Kumar Mahanta
Novel Test Fixture For Characterizing Mems Switch Microcontact Reliability And Performance, Protap Kumar Mahanta
Dissertations (1934 -)
Microelectromechanical systems (MEMS) switch is considered as a better alternative than the conventional solid-state DC and RF switches due to their low contact resistance approximately 1 Ω, near-zero power consumption approximately 0 W, low insertion loss approximately 0.2 dB, and high isolation approximately -30 dB. However, reliability is a great concern for them to be ubiquitously used by the industry for specific applications. Switching dynamics and microcontact surface physics play the critical role in determining their reliability. A simple, quick, and efficient test fixture is required to study the contact surface physics as well as to optimize the switching dynamics.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 …
Nonlinear Dynamics Of A Class Of Ring-Based Angular Rate Sensing And Energy Harvesting Systems, Ibrahim F Abdelhamid Gebrel
Nonlinear Dynamics Of A Class Of Ring-Based Angular Rate Sensing And Energy Harvesting Systems, Ibrahim F Abdelhamid Gebrel
Electronic Thesis and Dissertation Repository
This research is classified into two broad sections: ring-based MEMS (Micro-electro Mechanical Systems) and macro gyroscopes and novel bi-stable/monostable nonlinear energy harvesting systems. In both cases, models and solution methods are based on ring structural dynamics considering comprehensive nonlinear formulations. The investigation of nonlinear and linear dynamic response behavior of MEMS and macro ring gyroscopes forms the basis of the first study. This class of MEMS/macro ring-based vibratory gyroscopes requires oscillatory nonlinear electrostatic/electromagnetic excitation forces for their operation. The partial differential equations that govern the ring dynamics are reduced to a set of coupled nonlinear ordinary differential equations by assuming …
Feasibility Study Of Radio Frequency Microelectromechanical Filters For Space Operation, Karanvir Singh
Feasibility Study Of Radio Frequency Microelectromechanical Filters For Space Operation, Karanvir Singh
Theses and Dissertations
Piezoelectric contour mode resonator technology has the unique advantage of combining low motional resistance with the ability to define multiple frequencies on the same substrate. Contour mode resonators can be mechanically coupled together to form robust band-pass filters for the next generation of GPS satellites with extreme size reduction compared to electrically coupled filters. Piezoelectric zinc oxide (ZnO) contour mode resonators have the potential for monolithic integration with current ZnO transistor further reducing size, power consumption, and cost of filter modules. Barium strontium titanate (BST) contour mode resonators have incredible frequency tunability due to the fundamental nature of the thin …
Development Of Novel Compound Controllers To Reduce Chattering Of Sliding Mode Control, Mehran Rahmani
Development Of Novel Compound Controllers To Reduce Chattering Of Sliding Mode Control, Mehran Rahmani
Theses and Dissertations
The robotics and dynamic systems constantly encountered with disturbances such as micro electro mechanical systems (MEMS) gyroscope under disturbances result in mechanical coupling terms between two axes, friction forces in exoskeleton robot joints, and unmodelled dynamics of robot manipulator. Sliding mode control (SMC) is a robust controller. The main drawback of the sliding mode controller is that it produces high-frequency control signals, which leads to chattering. The research objective is to reduce chattering, improve robustness, and increase trajectory tracking of SMC. In this research, we developed controllers for three different dynamic systems: (i) MEMS, (ii) an Exoskeleton type robot, and …
Copper Electrodeposition In Full Wafer Thickness Through-Silicon Vias, Rebecca P. Schmitt
Copper Electrodeposition In Full Wafer Thickness Through-Silicon Vias, Rebecca P. Schmitt
Chemical and Biological Engineering ETDs
Through-silicon vias (TSVs) are a key interconnect technology for advanced packaging of microelectronic devices, and full wafer thickness TSVs are required for certain microelectromechanical systems (MEMS) applications. In this work, electrolytes containing copper sulfate, an acid, chloride, and Tetronic 701 suppressor were implemented for Cu filling of high aspect ratio (10:1), full wafer thickness TSVs. For each electrolyte system, rotating disk electrode voltammetry was used to identify a voltage range for bottom-up Cu filling in the TSVs. Die level feature filling was performed using voltage ramping, which moved active deposition through the vias to yield void-free Cu features. During voltage-controlled …
Modeling And Effects Of Non-Homogeneous Infiltration On Material Properties Of Carbon-Infiltrated Carbon Nanotube Forests, Daniel Owens Snow
Modeling And Effects Of Non-Homogeneous Infiltration On Material Properties Of Carbon-Infiltrated Carbon Nanotube Forests, Daniel Owens Snow
Theses and Dissertations
This work investigates the material properties and production parameters of carbon infiltrated carbon nanotube structures (CI-CNT's). The impact of non homogeneous infiltration and the porosity of cross section regions, coupled with changes in designed geometry, in this case beam width, on the density and modulus of elasticity are compared. Three potential geometric models of beam cross section are proposed and evaluated. 3-point bending, SEM images, and numerical optimization are used to assess the validity of each model and the implications they have for future CI-CNT material applications. Carbon capping near exterior beam surfaces is observed and determined to be a …
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 …
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 …
Development Of A Mems Fabrication Process On Soi To Study High Strain In Transition-Metal Dichalcogenides, Edgar Acosta
Development Of A Mems Fabrication Process On Soi To Study High Strain In Transition-Metal Dichalcogenides, Edgar Acosta
Open Access Theses & Dissertations
Over the recent years there has been an increasing demand of better performing electronics. However, as the semiconductor industry keeps on improving and scaling the technology to the nanometer regime, the passive power density has overcome the overall power consumption of transistors. The inability to reduce the power alongside the scaling of transistors has led the scientific community in the search for alternatives or different solutions to overcome this power crisis. The use of two-dimensional Transition-Metal Dichalcogenides (TMDCS) and Micro-Electro-Mechanical System (MEMS) actuators, in conjunction, has been proposed as an alternative solution [1]. Recent studies of TMDCS have shown a …
Parylene Based Flexible Multifunctional Biomedical Probes And Their Applications, Zhiguo Zhao
Parylene Based Flexible Multifunctional Biomedical Probes And Their Applications, Zhiguo Zhao
Wayne State University Dissertations
MEMS (Micro Electro Mechanical System) based flexible devices have been studied for decades, and they are rapidly being incorporated into modern society in various forms such as flexible electronics and wearable devices. Especially in neuroscience, flexible interfaces provide tremendous possibilities and opportunities to produce reliable, scalable and biocompatible instruments for better exploring neurotransmission and neurological disorders. Of all the types of biomedical instruments such as electroencephalography (EEG) and electrocorticography (ECoG), MEMS-based needle-shape probes have been actively studied in recent years due to their better spatial resolution, selectivity, and sensitivity in chronical invasive physiology monitoring. In order to address the inherent …
Development Of Micro-Scale High Aspect Ratio Patterned Features With Electroless Nickel Plating, Lorli Smith
Development Of Micro-Scale High Aspect Ratio Patterned Features With Electroless Nickel Plating, Lorli Smith
Theses and Dissertations--Mechanical Engineering
This thesis describes a novel method designed to pattern high aspect ratio metallic microscale features using a modified photolithography and electroless nickel plating process. This method utilizes modified photolithography techniques to create a polymer mold that is used to control the location of metal deposition on substrate during electroless nickel plating. In order to generate high aspect ratio mold features, a multiple spin-step process was developed to deposit thick layers of SU-8 photoresist, and inclined lithography was also used to generate tapered sidewalls that could help aid mold removal after plating. Results from electroplating experiments were evaluated using a Zygo …
Advanced Techniques For Carbon Nanotube Templated Microfabrication, Jason Matthew Lund
Advanced Techniques For Carbon Nanotube Templated Microfabrication, Jason Matthew Lund
Theses and Dissertations
Carbon nanotube templated microfabrication (CNT-M) is a term describing a grouping of processes where carbon nanotubes (CNTs) serve a structural role in the fabrication of a material or device. In its basic form, CNT-M is comprised of two steps: produce a template made from carbon nanotubes and infiltrate the porous template with an additional material. Vertically aligned carbon nanotube (VACNT) templates can be grown to heights ranging from microns to millimeters and lithographically patterned to a desired form. Deposition of an existing thin film material onto a CNT template will coat all template surfaces and can produce a near solid …
Multiple Imu Sensor Fusion For Suas Navigation And Photogrammetry, Matthew Givens
Multiple Imu Sensor Fusion For Suas Navigation And Photogrammetry, Matthew Givens
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Inertial measurement units (IMUs) are devices that sense accelerations and angular rates in 3D so that vehicles and other devices can estimate their orientations, positions, and velocities. While traditionally large, heavy, and costly, using mechanical gyroscopes and stabilized platforms, the recent development of micro-electromechanical sensor (MEMS) IMUs that are small, light, and inexpensive has led to their adoption in many everyday systems such as cell phones, video game controllers, and commercial drones. MEMS IMUs, despite their advantages, have major drawbacks when it comes to accuracy and reliability. The idea of using more than one of these sensors in an array, …
Low-Cost, Water Pressure Sensing And Leakage Detection Using Micromachined Membranes, Farhana Anwar
Low-Cost, Water Pressure Sensing And Leakage Detection Using Micromachined Membranes, Farhana Anwar
Master's Theses (2009 -)
This work presents the only known SOI membrane approach, using Microelectromechanical systems (MEMS) fabrication techniques, to address viable water leakage sensing requirements at low cost. In this research, membrane thickness and diameter are used in concert to target specific stiffness values that will result in targeted operational pressure ranges of approximately 0-120 psi. A MEMS membrane device constructed using silicon-on-insulator (SOI) wafers, has been tested and packaged for the water environment. MEMS membrane arrays will be used to determine operational pressure range by bursting.Two applications of these SOI membranes in aqueous environment are investigated in this research. The first …
Secondary Resonances Of Electrostatically Actuated Mems Cantilevers, Christopher I. Reyes
Secondary Resonances Of Electrostatically Actuated Mems Cantilevers, Christopher I. Reyes
Theses and Dissertations
In this work the behavior of micro-electromechanical (MEMS) cantilever resonators is investigated. The cantilever resonators are electrostatically actuated with hard AC voltage resulting in nine distinct resonances cases including super and subharmonic resonances. The amplitude frequency and amplitude voltage bifurcation diagrams are obtained for each of the nine resonance cases. Reduced order models (ROMs) are developed to include one and two modes of vibration. Three different methods are used to solve the ROMs namely 1) the method of multiple scales (MMS), which is a perturbation method used for one mode of vibration, 2) the homotopy analysis method (HAM), which is …
Liquid Flowmeter Using Thermal Measurement; Design And Application, Woojae Chung
Liquid Flowmeter Using Thermal Measurement; Design And Application, Woojae Chung
Master's Theses (2009 -)
This thesis presents flowmeter devices which can measure flowrate, pressure and temperature offlowing liquid samples using thermal measurement method. Typical thermal mass flowmeter usesthermal properties of materials to obtain flow features only for gases. We designed and fabricatedflowmeter devices with various functionalities such as: measuring properties of flowing liquid andidentifying the type of liquid samples.Thermal measurement methods using temperature sensor is a key of our flowmeter’s workingprinciple. The thermal mass flowmeter consists of a glass capillary, a tungsten wire heater, and aresistance temperature detector (RTD) sensor. The heater and sensors are integrated on …
Development Of A Counter-Flow Thermal Gradient Microfluidic Device, Shayan Davani
Development Of A Counter-Flow Thermal Gradient Microfluidic Device, Shayan Davani
Doctoral Dissertations
This work presents a novel counter-flow design for thermal stabilization of microfluidic thermal reactors. In these reactors, precise control of temperature of the liquid sample is achieved by moving the liquid sample through the thermal zones established ideally through the conduction in the solid material of the device. The goal here is to establish a linear thermal distribution when there is no flow and to minimize the temperature change at flow condition. External convection as well as internal flowinduced effects influence the prescribed thermal distribution. The counter-flow thermal gradient device developed in this study is capable of both stabilizing the …
Bouncing Dynamics Of A Class Of Mem/Nem Switching Systems, Mohamed Bognash
Bouncing Dynamics Of A Class Of Mem/Nem Switching Systems, Mohamed Bognash
Electronic Thesis and Dissertation Repository
The aim of the present research is to understand the bouncing dynamic behavior of NEM/MEM switches in order to improve the switch performance and reliability. It is well known that the bouncing can dramatically degrade the switch performance and life; hence, in the present study, bouncing dynamics of a cantilever-based NME/MEM switch has been studied in detail. To this end, a model of a MEM switch that incorporates electrostatic force, squeeze film air damping force as well as asperity-based contact force has been proposed for an electrostatically actuated switch. An actuation force due to piezoelectric effects is further included in …
Development Of A Sensing System For Underground Optic Fiber Cable Conduit Mapping, Sherif Bakr
Development Of A Sensing System For Underground Optic Fiber Cable Conduit Mapping, Sherif Bakr
All Graduate Theses, Dissertations, and Other Capstone Projects
The motivation of this research is to obtain an accurate three-dimensional (3D) layout of an underground conduit, which may be beneficial to optic fiber cable installers and engineers. A newly designed algorithm for 3D position tracking with the help of an inertial sensor and an encoder has been developed. Two types of representations (Euler angle and Quaternion) for orientation and rotation are also introduced, followed by several data pre-processing procedures. A sensing fusion method is utilized to overcome the accumulated errors introduced by the sensor drifting. Considering the application of 3D underground duct mapping in this research, a sensing system …
Conductivity Modulation In Strained 2d Transition- Metal- Dichalcogenides Via Micro- Electro- Mechanical Actuation, Aldo Ivan Vidaña
Conductivity Modulation In Strained 2d Transition- Metal- Dichalcogenides Via Micro- Electro- Mechanical Actuation, Aldo Ivan Vidaña
Open Access Theses & Dissertations
In this thesis, strain-induced conductivity modulation in bi-layer molybdenum disulfide (MoS2) flakes is experimentally investigated and modeled. Uniaxial tensile strain in the MoS2 flakes is achieved using a micro-electro-mechanical (MEM) actuator. Conductivity ratios up to 400 are demonstrated. Theoretical predictions of conductivity versus applied voltage in the MEMS-MoS2 device match experimental data reasonably well using only the effective width of the TMDC flakes as the sole fitting parameter. The amount of strain induced in the MoS2 flakes was determined to be as high as 2.7% for one flake using the model fitted to the experiment data. The switching energy required …
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 …
Development Of Microdialysis Probes In Series Approach Toward Eliminating Microdialysis Sampling Calibration: Miniaturization Into A Pdms Microfluidic Device, Randy Espinal Cabrera
Development Of Microdialysis Probes In Series Approach Toward Eliminating Microdialysis Sampling Calibration: Miniaturization Into A Pdms Microfluidic Device, Randy Espinal Cabrera
Graduate Theses and Dissertations
A new microdialysis sampling method and microfluidic device were developed in vitro. The method consisted of using up to four microdialysis sampling probes connected in series to evaluate the relative recovery (RR) of different model solutes methyl orange, fluorescein isothiocyanate (FITC)-dextran average mol. wt. 4,000 (FITC-4), FITC-10, FITC-20, and FITC-40. Different flow rates (0.8, 1.0, and 1.5 µL/min) were used to compare experimentally observed relative recoveries with theoretical estimations. With increasing the number of probes in series, the relative recovery increases and ~100% (99.7% ± 0.9%) relative recovery for methyl orange was obtained. For larger molecules such as fluorescein isothiocyanate …
Design And Evaluation Of Novel Attitude Estimation System Using Mems Sensors For Indoor Uas, Joshua Bruce Milam
Design And Evaluation Of Novel Attitude Estimation System Using Mems Sensors For Indoor Uas, Joshua Bruce Milam
Graduate Theses, Dissertations, and Problem Reports
Most small unmanned aerial systems in use today, employ extended Kalman filter sensor fusion algorithms in order to provide accurate estimations of attitude or orientation. These complex algorithms use measurements from GPS receivers and magnetometer sensors that can be rendered useless in GPS denied environments or areas of significant magnetic interference, such as inside buildings or other structures. The complexity of these algorithms makes them inaccessible for some researchers and hobbyists who wish to code their own attitude estimation algorithms. This complexity is also computationally expensive and requires processors that are powerful enough to operate the algorithms along with any …
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 …