Engineering Commons^™

Photonic Crystal Edge Couplers For Sensing Applications, Michael A. Zylstra

Electronic Thesis and Dissertation Repository

Microelectromechanical systems (MEMS) have not only enabled the development of inexpensive sensors but have also improved their performance by lowering their mass thus enabling faster sensor response. However, there are limitations regarding the mass-scaling of conventional MEMS sensors that prevent further miniaturization. This makes the measurement of distributed forces with high spatiotemporal resolution challenging. Optical-based sensors provide low-volume confinement of electromagnetic energy and enable further mass-scaling. This thesis investigates the application of an optical deflection sensing mechanism that relies on the position dependent coupling between dielectric-like edge states on nearby photonic crystal slabs for the purposes of acoustic pressure, wall …

Design, Development, And Evaluation Of Customized Electronics For Controlling A 5-Dof Magneto-Rheological Actuator Collaborative Robot, Ziqi Yang

Electronic Thesis and Dissertation Repository

In recent years, Magneto-Rheological (MR) fluids has been used in various fields such as robotics, automotive, aerospace, etc. The most common use of the MR fluids is within a clutch-like mechanism, namely an MR clutch. When mechanical input is coupled to the input part of the MR clutch, the MR clutch provides a means of delivering this mechanical input to its output, through the MR fluids. The combination of the mechanical input device and the MR clutch is called an MR actuator. The MR actuator features inherently compliance owing to the characteristic of the MR fluids while also offering higher …

Radiometric Correction Of Multispectral Cameras Using Photosensor Irradiance For Agronomy Applications, Nicholas S. Mitchell

Electronic Thesis and Dissertation Repository

Cloud coverage has a significant impact on the reflectance maps generated by multispectral cameras mounted on UAV's in small farm settings. The current approach is to calibrate the camera once before every flight and use the radiometric calibration map for the entire flight. In this work we have designed and built a downwelling and upwelling photosensor to work in sync with our custom multispectral camera. A dual reflectance panel implementation for the time dependent radiometric calibration of the multispectral camera is completed. The solar spectral irradiance curve is approximated using the current measurements from the downwelling photosensor and the ground …

Investigation Of Opto-Mechanics In Thin-Film Photonic Crystal Membranes, Brett D. Poulsen

Electronic Thesis and Dissertation Repository

Opto-mechanical interactions in photonic crystals (PC) require further investigation for their realization in practical applications. In particular their dynamic response and opto-mechanical coupling is not well understood. The static response of a thin-film 2D PC membrane was studied and the mechanical sensitivity of a static pressure sensor was increased by a factor of 4.9 times. A novel model formulation, correctly accounting for the fluid-structure interaction and the influence of nano-features, was developed to describe the dynamic response of a thin-film 2D PC membrane. The model accurately predicted damping response to within 10% as compared to experimental measurements. A novel 2D …

Design Of An All-Dielectric Sublayer For Enhanced Transmittance In Stacked Antenna Array Applications, Matthew Bester

Electronic Thesis and Dissertation Repository

In spatially constrained applications, the overlapping of antenna arrays can be unavoidable and its presence can lead to a blockage in the line-of-sight for the underlying antennas. Although previous investigations focused predominantly on the contribution of the ground plane and feed network-which were resolved through the use of frequency selective surfaces and proper feed network design, respectively-it is believed that the ground plane, substrate, and patch regions can emplace a substantial combined impedance. To rectify the transmission through these layers, an all-dielectric implementation is suggested based on the properties of complementary media and Fabry-Perot resonance shifting phenomena. Consequently, both spherical …

Simplified Numerical Models In Simulating Corona Discharge And Ehd Flows, Sara Mantach

Electronic Thesis and Dissertation Repository

Corona discharge is used in many practical applications. For designing and optimization of corona devices, the discharge phenomenon should be numerically simulated. Most often, the corona discharge model is simplified by neglecting the process dynamics and assuming a limited number of reactions and species. In the extreme case, monopolar corona models with just one species and no reactions are studied. However, there is a problem with determining boundary conditions for the space charge density. The simplest solution to this problem was suggested by Kaptzov, who hypothesized that the electric field on the electrode surface remains constant and equal to the …

Design Of Radio-Frequency Arrays For Ultra-High Field Mri, Ian R O Connell

Electronic Thesis and Dissertation Repository

Magnetic Resonance Imaging (MRI) is an indispensable, non-invasive diagnostic tool for the assessment of disease and function. As an investigational device, MRI has found routine use in both basic science research and medicine for both human and non-human subjects.

Due to the potential increase in spatial resolution, signal-to-noise ratio (SNR), and the ability to exploit novel tissue contrasts, the main magnetic field strength of human MRI scanners has steadily increased since inception. Beginning in the early 1980’s, 0.15 T human MRI scanners have steadily risen in main magnetic field strength with ultra-high field (UHF) 8 T MRI systems deemed to …

Charging Level And Deposition Of Droplets In Electrostatic Painting, Husam Osman

Electronic Thesis and Dissertation Repository

The process of electrostatic painting has become a very important method of coating in a wide range of industrial applications including those used in the automobile industry. The general principle of spray coating is to deposit liquid droplets or solid powder particles on coated targets having various shapes. The electrostatic coating process consists of three main stages: droplet formation and charging, transportation and deposition. The complication of this process is caused by various factors, such as the physical properties of the material to be used, the appropriate electrical and mechanical conditions and the target surface to be coated, which affects …

Electrohydrodynamic Enhancement Of Heat Transfer And Mass Transport In Gaseous Media, Bulk Dielectric Liquids And Dielectric Thin Liquid Films, Seyed Reza Mahmoudi

Electronic Thesis and Dissertation Repository

Controlling transport phenomena in liquid and gaseous media through electrostatic forces has brought new important scientific and industrial applications. Although numerous EHD applications have been explored and extensively studied so far, the fast-growing technologies, mainly in the semiconductor industry, introduce new challenges and demands. These challenges require enhancement of heat transfer and mass transport in small scales (sometimes in molecular scales) to remove highly concentrated heat fluxes from reduced size devices. Electric field induced flows, or electrohydrodynamics (EHD), have shown promise in both macro and micro-scale devices.

Several existing problems in EHD heat transfer enhancements were investigated in this thesis. …

Nanoplasmonic Sensors Based On Periodic Arrays Of Gold Nanoparticles, Hao Jiang

Electronic Thesis and Dissertation Repository

Nanoplasmonic sensors use the localized surface plasmon resonance (LSPR) of metal nanostructures to sense the refractive index change in a surface-bound layer caused by biomolecular interactions or changing chemical environment. In this thesis, four types of sensor configurations based on gold nanoparticle arrays are thoroughly investigated.

The first configuration is a periodic array of gold nanoparticles excited by the evanescent field of an optical waveguide mode. Since light carried by a waveguide mode propagates along the same plane of the periodicities, the coupling of nanoparticles are strongly affected by the photonic crystal lattice. This configuration is investigated both in simulations …

Fem-Fct Based Dynamic Simulation Of Trichel Pulse Corona Discharge In Point-Plane Configuration, Paria Sattari

Electronic Thesis and Dissertation Repository

In this thesis, a new two-dimensional numerical solver is presented for the dynamic simulation of the Trichel pulse regime of negative corona discharge in point-plane configuration. The goal of this thesis is to simulate the corona discharge phenomenon and to improve the existing models so that the results have an acceptable compatibility with the experimentally obtained data. The numerical technique used in this thesis is a combination of Finite Element Method (FEM) and Flux Corrected Transport (FCT). These techniques are proved to be the best techniques, presented so far for solving the nonlinear hyperbolic equations that simulate corona discharge phenomenon. …

Optical Power Splitting Techniques Using Photonic Crystal Line Defect Waveguides, Rajat Dey

Electronic Thesis and Dissertation Repository

“Photonic Crystals (PCs)” are dielectric or metallo-dielectric structures with periodic spatial alternations of refractive index on the scale of the wavelength of light. Many optical devices, based on PCs, have been proposed. There are multiple ways by which equal amount of power of incoming signals can be divided into two, three and four output channels; for example using multiple coupled photonic crystal waveguides, directional coupling and cascaded multimode PC waveguides. Ideally, the splitter should divide the input power equally into the output channels without significant reflection or radiation losses and should be compact in size. In this thesis we have …

Planar Photonic Crystal For Biosensor Applications, Anil Kumar Mudraboyina

Electronic Thesis and Dissertation Repository

Photonic crystals are the subject of intense study due to their capability to provide precise control of optical transmission characteristics through the choice of their periodic lattice parameters and the material with which they are fabricated. The sensitivity of photonic crystal band structure and defect transmission states to refractive index changes either at planar boundaries of a 2-D crystal or at individual lattice sites, make these structures potentially attractive for integrated point detection biosensor devices.

1-D Photonic crystal (PC) and 2-D PC based sensors were developed and studied in terms of sensitivity with different types materials functionalized on the surface. …

Addressing Computational Complexity Of Electromagnetic Systems Using Parameterized Model Order Reduction, Majid Ahmadloo

Electronic Thesis and Dissertation Repository

As operating frequencies increase, full wave numerical techniques such as the finite element method (FEM) become necessary for the analysis of high-frequency and microwave circuit structures. However, the FEM formulation of microwave circuits often results in very large systems of equations which are computationally expensive to solve. The objective of this thesis is to develop new parameterized model order eduction (MOR) techniques to minimize the computational complexity of microwave circuits. MOR techniques provide a mechanism to generate reduced order models from the detailed description of the original FEM formulation. The following contributions are made in this thesis:

1. The first …