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Development Of Facile Microfabrication Technologies For The Fabrication And Characterization Of Multimodal Impedimetric, Plasmonic, And Electrophysiological Biosensors, Cacie Hart
Electronic Theses and Dissertations, 2020-
The objective of this dissertation was to develop novel methods of patterning inorganic and organic materials, develop biocompatibility evaluations, and subsequently apply these methods toward developing biosensors and lab-on-a-chip devices, such as Interdigitated Electrodes (IDEs) and Microelectrode Arrays (MEAs) on non-traditional (such as nanostructured and plasmonic) polymer substrates or deploy these methods to enhance precision cellular placement on traditional (glass) MEA substrates. It was hypothesized that a combination of such facile microfabrication techniques and patterning technologies on traditional and non-traditional substrates would increase the sensitivity and selectivity of such sensor platforms by several orders of magnitude, and potentially introduce new …
Mechanical Behavior Assessment Of Ti-6al-4v Alloy Produced By Laser Powder Bed Fusion, Asif Mahmud
Mechanical Behavior Assessment Of Ti-6al-4v Alloy Produced By Laser Powder Bed Fusion, Asif Mahmud
Electronic Theses and Dissertations, 2020-
The present work correlates quasi-static, tensile mechanical properties of additively manufactured Ti-6Al-4V (Grade 23) alloy to the phase constituents, microstructure and fracture surface characteristics that changed with post-heat treatment of stress relief (670 °C for 5h) and hot isostatic pressing (HIP with 100MPa at 920 °C for 2h). Ti-6Al-4V alloy tensile specimens in both the horizontal (i.e., X and Y) and vertical (Z) directions were produced by laser powder bed fusion (LPBF) technique. Mechanical properties were determined using quasi-static, tensile testing for both the as-stress-relieved (ASR) and HIP specimens. For the ASR and HIP samples built in X, Y and …
Investigation Of Via Extrusion And The Effect Of Cap Layer For 3d Integrated Circuits, Golareh Jalilvand
Investigation Of Via Extrusion And The Effect Of Cap Layer For 3d Integrated Circuits, Golareh Jalilvand
Electronic Theses and Dissertations, 2020-
Copper (Cu) through-silicon via (TSV) is an essential structural and functional element in three-dimensional integration circuits (3D ICs), which offers substantial improvements in integration density, form factor, device performance, and power efficiency. However, Cu-filled TSVs are exposed to multiple thermal cycles during fabrication, test and operation, which lead to the development of considerable thermal stresses, in and around the vias, due to the large mismatch of the coefficient of thermal expansion (CTE) between Cu and silicon (Si). The stress subsequently raises reliability concerns, among which, via extrusion is an important one. Via extrusion can damage the adjacent components, in particular …
Parametric Investigation And Optimization For Inconel 718 Nickel-Based Superalloy In Laser Powder Bed Fusion, Thinh Huynh
Parametric Investigation And Optimization For Inconel 718 Nickel-Based Superalloy In Laser Powder Bed Fusion, Thinh Huynh
Electronic Theses and Dissertations, 2020-
Excellent weldability and high temperature stability make Inconel 718 (IN718) one of the most desired alloys to be produced by additive manufacturing (AM). Within the flourishing field of AM technology, laser powder bed fusion (LPBF) is a popular prospective candidate capable of fabricating complex and near net-shape engineering components that traditional manufacturing methods cannot accomplish. In this study, the effects of processing parameters on the relative density and microstructure was investigated. Gas atomized IN718 powders were used to fabricate cuboidal specimens via LPBF for metallographic characterization. The specimens were printed with independently varied laser power (125 - 350 W), laser …
Cerium Oxide Based Nanocomposites For Supercapacitors, Aadithya Jeyaranjan
Cerium Oxide Based Nanocomposites For Supercapacitors, Aadithya Jeyaranjan
Electronic Theses and Dissertations, 2020-
Access to clean, and sustainable energy is one of the biggest challenges of our generation. With the rapid growth of renewable energy harvesters, developing electrochemical energy storage devices (EEDs) that respond well to them is of significant interest. Supercapacitors are a class of EEDs with exceptional power densities and ultra-long cycle life. These properties make them an attractive candidate as a replacement, or to be used in combination with batteries and other EEDs. In this dissertation, nano cerium oxide (nano CeO2) based materials are examined as an active material for supercapacitor applications. The first part of this work details how …
Optimization Studies For The Gas Atomization And Selective Laser Melting Processes Of Al10simg Alloy, Sharon Park
Optimization Studies For The Gas Atomization And Selective Laser Melting Processes Of Al10simg Alloy, Sharon Park
Electronic Theses and Dissertations, 2020-
Selective laser melting (SLM) is an additive manufacturing technology that can fabricate complex engineering components using a scanning laser beam to melt consecutive layers of powders with characteristics that significantly influence material properties. Present work investigates both the gas atomization and SLM processes for the Al10SiMg alloy with a focus on establishing the relationships among atomization parameters, powder characteristics, SLM parameters and materials properties. Al10SiMg alloy powders (Al-10wt.%Si-0.5wt.%Mg) were batch-produced through gas atomization by systematically varying the melt flow rate (0.012 - 0.037 kg/s), gas pressure (1.4 - 3.1 MPa), and melt temperature (850C -1000C). The highest yield of 80 …
Non-Linear Inverse Liquid-Solid Chromatography As A Methodology To Characterize Drug Concentration Losses To Polymeric Materials Used In Body-On-A-Chip Devices For Drug Discovery, Mark Schnepper
Electronic Theses and Dissertations, 2020-
Body-on-a-chip and human-on-a-chip systems are currently being used to augment and could eventually replace animal models in drug discovery and basic biological research. However, hydrophobic molecules, especially therapeutic compounds, tend to adsorb to the polymer materials used to create these microfluidic platforms, which may distort the dose-response curves that feed into Pharmacokinetic/Pharmacodynamic (PK/PD) models which translate preclinical data into predictions of clinical outcomes. Adsorption of hydrophobic molecules to these polymer materials needs better characterization. Inverse Liquid-Solid Chromatography paired with a numerical optimization based on the Langmuir model of adsorption was used to characterize the adsorption isotherm parameters of selected drugs …
Diffusion Of Fission Products In Nuclear Graphite, Kevin Graydon
Diffusion Of Fission Products In Nuclear Graphite, Kevin Graydon
Electronic Theses and Dissertations, 2020-
The next generation of nuclear reactors (Generation IV) are specified to use graphite as the choice material for neutron moderation and structural components. For this reason, study of diffusion behavior of the fission product, ruthenium (Ru), in the candidate graphite grades, POCO AXF-5Q & ZXF-5Q, IG-110, NBG-18 and PCEA, is necessary. Diffusion data for Ru in these grades is absent due to the lack of prior studies and this work aims to fill this void and begin the study of this metallic fission product's diffusion behavior. By utilizing physical vapor deposition (PVD), dynamic secondary ion mass spectroscopy (SIMS), and the …
Atomic Layer Deposition Of Oxide Materials For Passivated Carrier Selective Contact Solar Cells, Geoffrey Gregory
Atomic Layer Deposition Of Oxide Materials For Passivated Carrier Selective Contact Solar Cells, Geoffrey Gregory
Electronic Theses and Dissertations, 2020-
Silicon-based devices have dominated the industrial solar cell marketplace for several decades, thanks to the low bulk defect concentration and technological relevance of silicon substrates. This has led to an oversupply of dopant-diffused homojunction technologies, which suffer from significant performance losses at the metal-silicon contact interface. In response, the research community has developed carrier-selective heterojunction contacts, which separate the metal from the silicon absorber with heavily-doped silicon layers. These novel contacts provide the same asymmetrical conductivity as the diffused junction in the previous generations of silicon solar cells, but with less processing complexity and greater device performance. Still, the silicon …
Designing Metal Nanocatalysts And Tuning Their Microenvironment For Gas-Involving Electrocatalysis, Lin Hu
Designing Metal Nanocatalysts And Tuning Their Microenvironment For Gas-Involving Electrocatalysis, Lin Hu
Electronic Theses and Dissertations, 2020-
In the development of renewable energy technologies, electrocatalysis plays a central role in energy conversion processes, such as fuel cells and electrochemical fuel synthesis. Development of such technologies relies on the rational design of electrocatalysts as well as understanding their interaction with the working environment. Here we focus on gas-involving electrocatalytic reactions, particularly nitrogen electroreduction to ammonia and formic acid electrooxidation to carbon dioxide. First, to understand the structure-activity relationships for nitrogen electroreduction on Ru, we prepared a series of size-controlled Ru nanoparticles using atomic layer deposition. Both catalytic activity and selectivity for ammonia production on Ru catalysts strongly depend …
Enhancement Of Absorptance By Ultrafast Laser Pulse Shaping For Efficient Laser Processing Of Thin Polymers, Arifur Rahaman
Enhancement Of Absorptance By Ultrafast Laser Pulse Shaping For Efficient Laser Processing Of Thin Polymers, Arifur Rahaman
Electronic Theses and Dissertations, 2020-
Ultrashort-pulsed lasers have been used for high precision processing of a wide range of materials including dielectrics, semiconductors, metals, and polymers/polymer composites, enabling numerous applications ranging from micromachining, photonics to life sciences. However, there are challenges when applying this technology in the industry, which requires scale and throughput different from lab use. The goal of this research is to understand how ultrafast laser pulses interact with thin polymers/polymer composite materials and develop a method that is efficient for ultrafast laser processing of these materials. It is a common practice in industrial applications to run the laser at a high repetition …
Understanding Solidification Behavior Of Selected Aluminum And Magnesium Alloys Additively Manufactured By Laser Powder Bed Fusion, Holden Hyer
Electronic Theses and Dissertations, 2020-
Additive manufacturing (AM), also known as 3D printing, has demonstrated the ability to produce customized, complex engineering components from metallic alloys, not previously possible with traditional techniques such as subtractive machining of cast alloys. However, many desired lightweight metallic alloys such as high strength aluminum (Al) and magnesium (Mg) alloys, cannot be processed dense with AM due to the consequence of solidification cracking. Thus, a large knowledge gap remains in assessing already existing, and genesis of new alloys that can be processed dense by AM, without solidification cracking. The present work investigates the AM processing and solidification behavior of selected …
The Reliability Of Through Glass Vias And Solder Joints For Three Dimensional Multi Functional Integrated Systems, Omar Ahmed
Electronic Theses and Dissertations, 2020-
Three-dimensional (3D) integration technologies, including interposer-based integration, are among the most promising solutions to meet the increased demand for high performance computing, high chip density, and small form factor. Key technologies that enable 3D integration include through-substrate vias and solder joints. Glass is considered as a promising substrate material for interposer-based 3D integration technology especially in radio frequency applications because of glass's high resistivity, low dielectric constant, low electrical loss, and the adjustable coefficient of thermal expansion (CTE). However, during fabrication or service, through-glass vias can suffer from interface delamination and substrate cracking. The problem of copper protrusion is also …
Additive Manufacturing Of Copper-Based Alloy By Laser Powder Bed Fusion, Binghao Lu
Additive Manufacturing Of Copper-Based Alloy By Laser Powder Bed Fusion, Binghao Lu
Electronic Theses and Dissertations, 2020-
Copper (Cu) and Cu-alloy are good candidates for the engineered components that require good thermal and electrical conductivity. Since industry often needs sophisticated components that cannot be made easily by traditional methods, such as casting, forging and machining, research for additive manufacturing of copper-based alloy is on demand. Therefore, this thesis focuses on the optimization of laser powder bed fusion (LPBF) of Cu-10 wt.% Sn alloy and pure Cu based on their characteristics such as relative density/porosity, surface roughness, phase constitutes, melt pool dimension, and dendrite arm spacings dimension, determined by optical microscopy, X-ray diffraction and Scanning electron microscope. LPBF, …
Development Of 3d Porous Chitosan-Based Platform For In Vitro Culture, Kailei Xu
Development Of 3d Porous Chitosan-Based Platform For In Vitro Culture, Kailei Xu
Electronic Theses and Dissertations, 2020-
Three-dimensional (3D) cell cultures have been widely used in biological research since two-dimensional (2D) cultures have many limitations including alteration of cell morphology, metabolic pathways and gene expression. Therefore, the application of 2D cell cultures in pharmaceutical companies for drug screening causes reproducibility issues in animal studies, which strongly influences the efficiency of drug development. The aim of my studies is to develop 3D cell culture models to better mimic the extracellular matrix (ECM) in tumor microenvironment, not only for deeper understanding of interaction between cells and ECM, but also for the application in drug screening. Three different compositions of …
Integrating Graphene Into Polymer Derived Ceramics Towards The Development Of New Thermoelectric Materials, Elizabeth Barrios
Integrating Graphene Into Polymer Derived Ceramics Towards The Development Of New Thermoelectric Materials, Elizabeth Barrios
Electronic Theses and Dissertations, 2020-
Radioisotope thermoelectric generators (RTGs) have been an enabling technology for the exploration of deep space since the dawn of the Space Age. Since its first deployment in a meteorological satellite in the late 1960's, RTGs have been used to provide solid-state, maintenance-free power to 27 American spacecraft and scientific instruments. While showing great success in the past, the future usage of thermoelectric devices is limited by the low operating efficiencies and the use of hazardous or expensive materials, limiting the use of thermoelectric technologies to niche applications such as space exploration. Current research efforts that address these disadvantages have focused …