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Full-Text Articles in Physical Sciences and Mathematics
Design And Characterization Of A Miniaturized Spectrometer For Wearable Applications, Tyler Richard Westover
Design And Characterization Of A Miniaturized Spectrometer For Wearable Applications, Tyler Richard Westover
Theses and Dissertations
As individual health monitors continue to become more widely adopted in helping individuals make informed decisions, new technologies need to be developed to obtain more biometric data. Spectroscopy is a well-known tool to gain biological information. Traditionally spectrometers are large and expensive making personal or wearable health monitors difficult. Here we present the development and characterization of a miniaturized short wavelength infrared spectrometer for wearable applications. We present a carbon nanotube parallel hole collimator can effectively select a narrow set of allowed angles of light to be separated by a linear variable filter and detected at a photodiode array making …
Patterned And Infiltrated Vertically Aligned Carbon Nanotube Ultra-Black Materials, Kevin Laughlin
Patterned And Infiltrated Vertically Aligned Carbon Nanotube Ultra-Black Materials, Kevin Laughlin
Theses and Dissertations
Ultra-black materials reflect less than 1% of incident light, and are used in a wide variety of applications from low signal detector systems, to jewelry. The darkest ultra-black materials are made with vertically aligned carbon nanotubes (VACNTs). One downside to these VACNT based ultra-black material, is they are extremely fragile, and the types of surfaces they can be grown on is limited. Here I created a strengthened ultra-black material that can withstand light handling and drying from water exposure, and can be transferred to other substrates while remaining ultra-black. I also present theoretical models with supporting data on how to …
Electrical Conductivity Of The Aluminum Oxide Diffusion Barrier Following Catalytic Carbon Nanotube Growth, Berg Daniel Dodson
Electrical Conductivity Of The Aluminum Oxide Diffusion Barrier Following Catalytic Carbon Nanotube Growth, Berg Daniel Dodson
Theses and Dissertations
Carbon nanotube templated microfabrication (CNT-M) is a method that allows high-aspect ratio structures to be made for microelectromechanical systems (MEMS) devices. One concern when making monolithic electrical devices using CNT-M is that the aluminum oxide diffusion barrier will create too large of a resistance in the device. However, in developing CNT based MEMS devices, it has been observed that an electrical DC current is capable of transport from a conductive substrate, across the aluminum oxide, and through to the CNT structure grown on top of it. This thesis attempts to determine the mechanisms responsible for current being able to cross …
Penetration Depth Variation In Atomic Layer Deposition On Multiwalled Carbon Nanotube Forests, David Alan Kane
Penetration Depth Variation In Atomic Layer Deposition On Multiwalled Carbon Nanotube Forests, David Alan Kane
Theses and Dissertations
Atomic Layer Deposition (ALD) of Al2O3 on tall multiwalled carbon nanotube forests shows concentration variation with the depth in the form of discrete steps. While ALD is capable of extremely conformal deposition in high aspect ratio structures, decreasing penetration depth has been observed over multiple thermal ALD cycles on 1.3 mm tall multiwalled carbon nanotube forests. SEM imaging with Energy Dispersive X-ray Spectroscopy elemental analysis shows steps of decreasing intensity corresponding to decreasing concentrations of Al2O3. A study of these steps suggests that they are produced by a combination of diffusion limited delivery of precursors with increasing precursor adsorption site …
Microfabrication With Smooth, Thin Cnt/Polymer Composite Sheets, Nathan Edward Boyer
Microfabrication With Smooth, Thin Cnt/Polymer Composite Sheets, Nathan Edward Boyer
Theses and Dissertations
Carbon nanotube (CNT)/polymer composite sheets can be extremely high strength and lightweight, which makes them attractive for fabrication of mechanical structures. This thesis demonstrates a method whereby smooth, thin CNT/polymer composite sheets can be fabricated and patterned on the microscale using a process of photolithography and plasma etching. CNT/polymer composites were made from CNTs grown using chemical vapor deposition using supported catalyst growth and floating catalyst growth. The composite sheets had a roughness of approximately 30nm and were about 61¼m or 261¼m depending on whether they were made from supported catalyst grown or floating catalyst grown CNTs. The composites were …
Silicon Carbon Nanotube Lithium Ion Batteries, Lawrence Kent Barrett
Silicon Carbon Nanotube Lithium Ion Batteries, Lawrence Kent Barrett
Theses and Dissertations
Silicon has the highest theoretical capacity of any known anode material, and silicon coated carbon nanotubes (Si-CNTs) have shown promise of dramatically increasing battery capacity. However, capacity fading with cycling and low rate capability prevent widespread use. Here, three studies on differing aspects of these batteries are presented. Here, three studies on differing aspects of these batteries are presented. The first examines the rate capability of these batteries. It compares the cycling of electrodes hundreds of microns thick with and without ten micron access holes to facilitate diffusion. The holes do not improve rate capability, but thinner coatings of silicon …
Fabrication, Characterization, Optimization And Application Development Of Novel Thin-Layer Chromatography Plates, Supriya Singh Kanyal
Fabrication, Characterization, Optimization And Application Development Of Novel Thin-Layer Chromatography Plates, Supriya Singh Kanyal
Theses and Dissertations
This dissertation describes advances in the microfabrication of thin layer chromatography (TLC) plates. These plates are prepared by the patterning of carbon nanotube (CNT) forests on substrates, followed by their infiltration with an inorganic material. This document is divided into ten sections or chapters. Chapter 1 reviews the basics of conventional TLC technology. This technology has not changed substantially in decades. This chapter also mentions some of the downsides of the conventional approach, which include unwanted interactions of the binder in the plates with the analytes, relatively slow development times, and only moderately high efficiencies. Chapter 2 focuses primarily on …
Thin Films Of Carbon Nanotubes And Nanotube/Polymer Composites, Anthony D. Willey
Thin Films Of Carbon Nanotubes And Nanotube/Polymer Composites, Anthony D. Willey
Theses and Dissertations
A method is described for ultrasonically spraying thin films of carbon nanotubes that have been suspended in organic solvents. Nanotubes were sonicated in N-Methyl-2-pyrrolidone or N-Cyclohexyl-2-pyrrolidone and then sprayed onto a heated substrate using an ultrasonic spray nozzle. The solvent quickly evaporated, leaving a thin film of randomly oriented nanotubes. Film thickness was controlled by the spray time and ranged between 200-500 nm, with RMS roughness of about 40 nm. Also described is a method for creating thin (300 nm) conductive freestanding nanotube/polymer composite films by infiltrating sprayed nanotube films with polyimide.
Microfabrication, Characterization, And Application Of Carbon Nanotube Templated Thin Layer Chromatography Plates, And Functionalization Of Porous Graphitic Carbon, David S. Jensen
Theses and Dissertations
This dissertation contains the following sections. Chapter 1 contains a detailed description of the theory of thin layer chromatography (TLC). Chapter 2 describes the benefits and practical considerations of elevated temperatures in liquid chromatography (LC). The porous graphitic carbon (PGC) I modified as part of my work is often used in elevated temperature LC. Chapter 3 shows a thermodynamic analysis of chromatographic retention at elevated temperature, and Chapter 4 contains a closer look at the van 't Hoff equation in LC and how it can be used in retention modeling. In Chapter 5, I describe a new procedure for microfabricating …
Massively Parallel Indirect Dielectrophoresis Controlled Placement Of Carbon Nanotubes, Hiram Jacob Conley
Massively Parallel Indirect Dielectrophoresis Controlled Placement Of Carbon Nanotubes, Hiram Jacob Conley
Theses and Dissertations
Placement of single walled carbon nanotubes is demonstrated through massively parallel indirect dielectrophoresis (MPID). MPID is shown to be able to control the placement of carbon tubes as well as the number of tubes placed. Lumped element analysis for AC circuits is used to model MPID. This model allows for predictions of the number of tubes that will be captured in a trap. This model has been consistent with experimental data of numbers of nanotube placed in a junction. Carbon nanotubes placed with MPID are shown to be electrically active.