Engineering Commons^™

Recent Progress In Microrna Detection Using Integrated Electric Fields And Optical Detection Methods, Logeeshan Velmanickam, Dharmakeerthi Nawarathna

Electrical & Computer Engineering Faculty Publications

Low-cost, highly-sensitivity, and minimally invasive tests for the detection and monitoring of life-threatening diseases and disorders can reduce the worldwide disease burden. Despite a number of interdisciplinary research efforts, there are still challenges remaining to be addressed, so clinically significant amounts of relevant biomarkers in body fluids can be detected with low assay cost, high sensitivity, and speed at point-of-care settings. Although the conventional proteomic technologies have shown promise, their ability to detect all levels of disease progression from early to advanced stages is limited to a limited number of diseases. One potential avenue for early diagnosis is microRNA (miRNA). …

Ultra-Low Intensity Post-Pulse Affects Cellular Responses Caused By Nanosecond Pulsed Electric Fields, Kamal Asadipour, Carol Zhou, Vincent Yi, Stephen J. Beebe, Shu Xiao

Electrical & Computer Engineering Faculty Publications

High-intensity nanosecond pulse electric fields (nsPEF) can preferentially induce various effects, most notably regulated cell death and tumor elimination. These effects have almost exclusively been shown to be associated with nsPEF waveforms defined by pulse duration, rise time, amplitude (electric field), and pulse number. Other factors, such as low-intensity post-pulse waveform, have been completely overlooked. In this study, we show that post-pulse waveforms can alter the cell responses produced by the primary pulse waveform and can even elicit unique cellular responses, despite the primary pulse waveform being nearly identical. We employed two commonly used pulse generator designs, namely the Blumlein …

Long-Range Aceo Phenomena In Microfluidic Channel, Diganta Dutta, Keifer Smith, Xavier Palmer

Electrical & Computer Engineering Faculty Publications

Microfluidic devices are increasingly utilized in numerous industries, including that of medicine, for their abilities to pump and mix fluid at a microscale. Within these devices, microchannels paired with microelectrodes enable the mixing and transportation of ionized fluid. The ionization process charges the microchannel and manipulates the fluid with an electric field. Although complex in operation at the microscale, microchannels within microfluidic devices are easy to produce and economical. This paper uses simulations to convey helpful insights into the analysis of electrokinetic microfluidic device phenomena. The simulations in this paper use the Navier–Stokes and Poisson Nernst–Planck equations solved using COMSOL …

Assembly Of Alumina Particles In Aqueous Suspensions Induced By High‐Frequency Ac Electric Field, James E. John, Shizhi Qian, Dipankar Ghosh

Mechanical & Aerospace Engineering Faculty Publications

The role of high-frequency alternating current (AC) electric field in the assembly of alumina particles in aqueous media was investigated. Field–particle interactions were in situ investigated for coarse and fine powder particles in very dilute suspensions. For both coarse and fine particles, AC field-induced assembly led to the formation of chains of particles within a minute, which were aligned in the field direction. However, a much finer network of particle chains evolved in fine particle suspensions. Threshold field strength for chain formation was also lower for fine particles (28 V/mm) than for coarse particles (50 V/mm), suggesting stronger interactions for …

Quadrupoles For Remote Electrostimulation Incorporating Bipolar Cancellation, Shu Xiao, Ryo Yamada, Carol Zhou

Bioelectrics Publications

Introduction: A method that utilizes nanosecond bipolar cancellation (BPC) near a quadrupole electrodes to suppress a biological response but cancels the distal BPC at the quadrupole center, i.e., cancellation of cancellation (CANCAN), may allow for a remote focused stimulation at the quadrupole center.

Objectives: The primary object of this study was to outline the requirement of the CANCAN implementation and select an effective quadrupole configuration.

Results: We have studied three quadrupole electrode configurations, a rod quadrupole, a plate quadrupole (Plate-Q), and a resistor quadrupole. The pulse shapes of electric fields include monophasic pulses, cancellation pulses, and additive pulses. The Plate-Q …

Generation Of Large-Volume High-Pressure Plasma By Spatiotemporal Control Of Space Charge, Shirshak K. Dhali

Electrical & Computer Engineering Faculty Publications

Any attempt to scale pressure and volume of nonthermal plasma usually leads to instabilities due to the formation of localized space charge. The control of the plasma is limited by the discharge geometry, type of excitation, and gas composition. This article explores the possibility of controlling the space charge in a discharge with a spatially and temporally varying electric field. It is shown that a phase-staggered sinusoidal excitation to a set of conformal azimuthal electrodes in a cylindrical geometry leads to a traveling electric field. Simulations show that in space charge dominated transport, the charged species are dispersed both in …

Measurement Of Electron Density And Temperature From Laser-Induced Nitrogen Plasma At Elevated Pressure (1–6 Bar), Ashwin P. Rao [*], Mark Gragston, Anil K. Patnaik, Paul S. Hsu, Michael B. Shattan

Faculty Publications

Laser-induced plasmas experience Stark broadening and shifts of spectral lines carrying spectral signatures of plasma properties. In this paper, we report time-resolved Stark broadening measurements of a nitrogen triplet emission line at 1–6 bar ambient pressure in a pure nitrogen cell. Electron densities are calculated using the Stark broadening for different pressure conditions, which are shown to linearly increase with pressure. Additionally, using a Boltzmann fit for the triplet, the electron temperature is calculated and shown to decrease with increasing pressure. The rate of plasma cooling is observed to increase with pressure. The reported Stark broadening based plasma diagnostics in …

Aluminum Multicharged Ion Generation From Femtosecond Laser Plasma, Md. Haider A. Shaim, Frederick Guy Wilson, Hani E. Elsayed-Ali

Electrical & Computer Engineering Faculty Publications

Aluminum multicharged ion generation from femtosecond laser ablation is studied. A Ti:sapphire laser (wavelength 800 nm, pulse width ∼100 fs, and maximum laser fluence of 7.6 J/cm²) is used. Ion yield and energy distribution of each charge state are measured. A linear relationship between the ion charge state and the equivalent acceleration energy of the individual ion species is observed and is attributed to the presence of an electric field within the plasma-vacuum boundary that accelerates the ions. The ion energy distribution follows a shifted Coulomb-Boltzmann distribution. For Al¹⁺ and Al²⁺, the ion energy distributions …

Engineered Surfaces To Control Secondary Electron Emission For Multipactor Suppression, James M. Sattler, Ronald A. Coutu Jr., Robert A. Lake, Tod V. Laurvick

Electrical and Computer Engineering Faculty Research and Publications

A significant problem for space-based systems is multipactor - an avalanche of electrons caused by repeated secondary electron emission (SEE). The consequences of multipactor range from altering the operation of radio frequency (RF) devices to permanent device damage. Existing efforts to suppress multipactor rely heavily on limiting power levels below a multipactor threshold [1]. This research applies surface micromachining techniques to create porous surfaces to control the secondary electron yield (SEY) of a material for multipactor suppression. Surface characteristics of interest include pore aspect ratio and density. A discussion is provided on the advantage of using electroplating (vice etching) to …

Mechanism Of Radio-Frequency Current Collapse In Gan-Algan Field-Effect Transistors, A. Tarakji, Grigory Simin, N. Ilinskaya, X. Hu, A. Kumar, A. Koudymov, J. Yang, M. Asif Khan, M. S. Shur, R. Gaska

Grigory Simin

The mechanism of radio-frequency current collapse in GaN–AlGaN heterojunctionfield-effect transistors(HFETs) was investigated using a comparative study of HFET and metal–oxide–semiconductor HFET current–voltage (I–V) and transfer characteristics under dc and short-pulsed voltage biasing. Significant current collapse occurs when the gate voltage is pulsed, whereas under drain pulsing the I–V curves are close to those in steady-state conditions. Contrary to previous reports, we conclude that the transverse electric field across the wide-band-gap barrier layer separating the gate and the channel rather than the gate or surface leakage currents or high-field effects in the gate–drain spacing is responsible for the current collapse. We …

Ablation Of Myocardial Tissue With Nanosecond Pulsed Electric Fields, Fei Xie, Frency Varghese, Andrei G. Pakhomov, Iurii Semenov, Shu Xiao, Jonathan Philpott, Christian Zemlin

Bioelectrics Publications

Background

Ablation of cardiac tissue is an essential tool for the treatment of arrhythmias, particularly of atrial fibrillation, atrial flutter, and ventricular tachycardia. Current ablation technologies suffer from substantial recurrence rates, thermal side effects, and long procedure times. We demonstrate that ablation with nanosecond pulsed electric fields (nsPEFs) can potentially overcome these limitations.

Methods

We used optical mapping to monitor electrical activity in Langendorff-perfused New Zealand rabbit hearts (n = 12). We repeatedly inserted two shock electrodes, spaced 2–4 mm apart, into the ventricles (through the entire wall) and applied nanosecond pulsed electric fields (nsPEF) (5–20 kV/cm, 350 ns duration, …

Generation Of Bipolar Nanosecond Pulses, Sambasiva Rao Rajulapati

Electrical & Computer Engineering Theses & Dissertations

Bipolar pulse generation has been studied using transmission line technology, which was mainly used for monopolar pulse generation. In this thesis, low impedance, high current, nanosecond pulse generators were designed, constructed and tested. Five transmission lines were connected in parallel, so the impedance was 10 n. The transmission lines were switched by a spark gap switch operated in air. The closing of the switch creates a matched condition on one side of the transmission lines and a short circuit on the other side of the transmission lines. When the transmission lines are precharged, one of the two waves in opposite …

Analytical Parametric Model Used To Study The Influence Of Electrostatic Force On Surface Coverage During Electrospinning Of Polymer Fibers, Joshua Beisel, Jerry Kyeremateng, Lance Purkett, Jessica Andriolo, Jack L. Skinner

Electrical Engineering

Electrospinning (ES) can readily produce polymer fibers with cross-sectional dimensions ranging from tens of nanometers to tens of microns. Qualitative estimates of surface area coverage are rather intuitive. However, quantitative analytical and numerical methods for predicting surface coverage during ES have not been covered in sufficient depth to be applied in the design of novel materials, surfaces, and devices from ES fibers. This article presents a modeling approach to ES surface coverage where an analytical model is derived for use in quantitative prediction of surface coverage of ES fibers. The analytical model is used to predict the diameter of circular …

Proteins In High Electric Fields, David Michael Landry

Theses and Dissertations

Being able to control protein function directly and in real time is attractive. In this thesis, I discuss controlling protein activity using alternating current electric fields on the order of 1 MV/m. Since protein structures result in localized and/or protein-wide charge gradients, it is expected that a sufficiently high electric field applied across a protein should result in structural distortions which can temporarily alter or halt protein function. The field is set to oscillate above the influences of the electrochemical double layer effects (1 kHz) and below the level needed for hydrodynamic rotation of proteins (10 MHz). A device is …

Domain Rotation Induced Strain Effect On The Magnetic And Magneto-Electric Response In Cofe2o₄/Pb(Mg,Nb)O₃-Pbtio₃ Heterostructures, Zhiguang Wang, Ravindranath Viswan, Bolin Hu, Jie-Fang Li, V. G. Harris, D. Viehland

Vincent G. Harris

The present work shows good control of both magnetic and electric properties with electric and magnetic fields, respectively, for epitaxial CoFe2O4 (CFO) films on Pb(Mg,Nb)O3-PbTiO3 (PMN-PT). X-ray reciprocal space mapping revealed a transformation between a- and c-domains in the PMN-PT under electric field (E). Magnetic hysteresis loop and magnetic force microscopy (MFM) measurements showed a considerable change in the magnetic properties in specific areas of CFO layers poled by MFM probe tips. Furthermore, a pulsed electric field applied to the substrate was found to switch the magnetization of CFO between high and low values, depending on the polarity of E.

Modelling Of Polyaniline For Wi-Fi Electromagnetic Interference Shielding, Whamid Al-Shabib, Stefan W. Lachowicz

Research outputs 2013

In this paper COMSOL model is used to model the s-parameters of the electromagnetic shielding of layer/layers of Polyaniline (PAni) for Wi-Fi Electromagnetic Interference (EMI) shielding. PAni has a good future for minimizing the problems with Electromagnetic Shielding (EMS), and will be increasingly be used to provide protection from Electromagnetic Radiation (EMR) and Electromagnetic Interference (EMI). With the increased development in Wi-Fi and telecommunications equipment, a simple model is required to test for transmission losses. In this paper the electromagnetic radiation from antenna, positioned 30cm from PAni shielding device is modelled using COMSOL 4.2. The paper predicts the radiation reduction …

Subnanosecond Exposure Systems For Biological Studies, Jongbong Nah

Electrical & Computer Engineering Theses & Dissertations

The research of bioelectrics has expanded to subnanosecond pulse region and entered a new domain of biophysics of cell interaction with ultra-short and intense electric fields. As subnanosecond pulses may be delivered by antennas to the human body and is very attractive to the medical community, the study of subnanosecond pulse effects calls for exposure systems for both cells and tissues. Two systems were designed in the scope of this thesis, used for cells and tissues respectively. The exposure system designed for cell exposure is a cuvette consisting of two parallel aluminum gaps. This cuvette is placed in a coaxial …

Oxygen Vacancies Adjacent To Cu(2+) Ions In Tio(2) (Rutile) Crystals, A. T. Brant, Shan Yang (杨山), Nancy C. Giles, Zafar Iqbal, A. Manivannan, Larry E. Halliburton

Faculty Publications

Electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) are used to characterize Cu²⁺ ions substituting for Ti⁴⁺ ions in nominally undoped TiO₂ crystals having the rutile structure. Illumination at 25 K with 442 nm laser light reduces the concentration of Cu²⁺ ions by more than a factor of 2. The laser light also reduces the EPR signals from Fe³⁺ and Cr³⁺ ions and introduces signals from Ti³⁺ ions. Warming in the dark to room temperature restores the crystal to its preilluminated state. Monitoring the recovery of the photoinduced changes in the Cu …

Role Of Hydrodynamic Behavior Of Dna Molecules In Dielectrophoretic Polarization Under The Action Of An Electric Field, Hui Zhao

Mechanical Engineering Faculty Research

A continuum model is developed to predict the dielectrophoretic polarizability of coiled DNA molecules under the action of an alternating current electric field. The model approximates the coiled DNA molecule as a charged porous spherical particle. The model explains the discrepancies among scaling laws of polarizability of different-sized DNA molecules with contour length and such discrepancies are attributed to different hydrodynamic behavior. With zero or one fitting parameter, theoretical predictions are in good agreement with various experimental data, even though in experiments there are some uncertainties in regard to certain parameters.

Human Osteoblast Proliferation In Culture Following A Nanosecond Pulsed Electric Field (Nspef), Leonard Joseph Carinci Jr.

Biological Sciences Theses & Dissertations

Osteoblasts are mononucleate bone forming cells responsible for the deposition of new bone. Application of mechanical stress on bone reveals its ability to produce and release electric potentials across the cell membrane called piezoelectricity. The electric potentials produced in response to mechanical stress may have a direct correlation on osseous cells and the signaling pathways that regulate proliferation. Nanosecond pulsed electric fields (nsPEFs) are high intensity, ultrashort pulses which have the ability to maintain the integrity of the cell membrane by avoiding traditional electroporation. We delivered 8 nsPEFs (0.5 Hz) of a 25 kV/cm or 35 kV/cm electric field strength …

Electric Field Analysis In Insulating Films For Complex Electrode Systems, Anusha Jambula

Electrical & Computer Engineering Theses & Dissertations

Complex electrode systems with thin insulating materials demand careful examination of field distribution near the electrodes to improve the breakdown characteristics of dielectrics and optimal utilization of the space. The present work contributes to an extended research of physical electrode systems, namely axi-symmetric and non-uniform field systems. In an attempt to optimize the dimensions of the electrode system for subsequent use in electrical measurements, such as electroluminescence, capacitance and conduction current, field values at key points (sharp edges and triple junctions) in an axi-symmetric electrode system are simulated as a function of clearances between low voltage and guard electrodes. Since …

Electric Field Computation Of Wet Insulating Surfaces, Bhargavi Sarang

Electrical & Computer Engineering Theses & Dissertations

High voltage outdoor insulators form the backbone of modem power systems and therefore play a pivotal role in reliable supply of power. The presence of water droplets/films due to rain, fog, etc. enhances the electric field intensity and leads to electrical breakdown subsequently affecting the longevity of the insulator. The magnitude of surface E-fields necessary for initiation of electrical breakdown is a function of water repellent characteristic of an insulator called hydrophobicity. Thus, knowledge of field distribution around water droplets/films at various hydrophobic levels is significant in designing a better insulating material.

The current research analyzed electric field distributions on …

On The Effect Of Hydrodynamic Slip On The Polarization Of A Nonconducting Spherical Particle In An Alternating Electric Field, Hui Zhao

Mechanical Engineering Faculty Research

The polarization of a charged, dielectric, spherical particle with a hydrodynamically slipping surface under the influence of a uniform alternating electric field is studied by solving the standard model (the Poisson–Nernst–Planck equations). The dipole moment characterizing the strength of the polarization is computed as a function of the double layer thickness, the electric field frequency, the particle’s surface charge, and the slip length. Our studies reveal that two processes contribute to the dipole moment: ion transport inside the double layer driven by the electric field and the particle’s electrophoretic motion. The hydrodynamic slip will simultaneously impact both processes. In the …

Native Earth Electric Field Measurements Using Small Spacecraft In Low Earth Orbit, John A. Pratt

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The use of small satellites to measure the native electric field of the earth has historically presented many problems as a result of the generally modest pointing capabilities of small satellites. In spite of this, the cost of small satellites makes them ideal for just such scientific missions. This thesis details many of the constraints of electric field measuring missions as well as the requirements on any spacecraft designed to accomplish such. The data from a small sounding rocket mission is then analyzed and its usefulness discussed. Possible other methods for use are also discussed.

Microfabrication Of An Optical Chamber For Exposing Living Cells To Pulsed Electric Fields, Saleh Sheikh

Electrical & Computer Engineering Theses & Dissertations

I have fabricated a chamber which enables the application of Nanosecond Pulsed Electric Fields (nsPEFs) to living cells while monitoring their real time fluorescence with an inverted microscope. The No. I thickness (150µm nominal) coverslip glass substrate used for fabrication allows the use of high numerical aperture oil immersion objectives for imaging intracellular organelles. Electrodes are fabricated by first evaporating a chromium adhesion layer, followed by a nickel seed layer. Subsequently, an ultra-thick positive photoresist is applied and patterned to create a 30µm thick electroplating mold. The electrodes are then electrodeposited into the mold from a nickel sulfamate plating bath. …

The Effects Of Ultrashort Pulsed Electric Fields On The Fluorescent Molecule Bodipy Fl C5 Ceramide, Rachael Sara Shevin

Electrical & Computer Engineering Theses & Dissertations

Nanosecond pulsed electric fields are able to manipulate internal cell organelles by taking advantage of the small but finite time required for charge to establish across a capacitive barrier. Pulsed electric fields also affect macromolecular structures such as enzymes and proteins. Application of a single nanosecond pulsed electric field decreases the fluorescence of a commercially available biological dye Bodipy FL C₅ Ceramide, used to observe the Golgi apparatus of living cells. The effect is seen when the fluorophore is exposed to an electric field both in vitro and when incorporated into the Golgi of a living Jurkat cell. Observation …

Comparison Of Near-Field Millimeter-Wave Probes For Detecting Corrosion Precursor Pitting Under Paint, Mohammad Tayeb Ahmad Ghasr, Sergey Kharkovsky, R. Zoughi, Russell A. Austin

Electrical and Computer Engineering Faculty Research & Creative Works

Aircraft structural components such as wings and fuselages are constantly exposed to harsh environments, which make them susceptible to corrosion initiation and growth. To complicate matters, corrosion is normally hidden under paint and primer and cannot be visually detected until significant corrosion has occurred, causing the paint to blister. Corrosion of this type is usually preceded by the presence of corrosion precursor pitting. Hence, early detection of pitting is a critical issue in the maintenance of an aircraft and its structural components. Near-field microwave nondestructive testing techniques have been successfully used for detection of corrosion under paint, including very small …

Real-Time Measurements On The Effects Of Ultra-Short High Voltage Pulses On Hl-60 Cells, Michalis C. Artemiou

Electrical & Computer Engineering Theses & Dissertations

The application of high voltage microsecond pulses that are above a critical value, to biological cells, has been shown to cause electroporation (Neumann, 1989). In addition, ultra-short pulses of several tens to hundreds of nanoseconds duration have been recently shown to affect intracellular structures without disturbing the plasma membrane (Schoenbach, 2001). However, such ultra-short intense pulses are expected to cause deformation of cells due to Maxwell stresses. This deformation was studied by means of an imaging technique with 10 ns temporal resolution on HL-60 cells. The imaging system consists of an inverted microscope where a spark light source was used …

Comparative Study On The Use Of Coherent Radar-Derived Electric Fields Vs. Statistical Electric Fields For The Initialization Of A High-Latitude Ionospheric Model, Christopher M. Hogue

Theses and Dissertations

The structure and time development of the magnetosphere-ionosphere system have significant impacts on the Air Force and its mission. Specifically, an accurate knowledge of ionospheric plasma densities is important for the operation of many Air Force systems. This research analyzes plasma density structure development through comparing two distinct electric field models. The two models compared here are a commonly used statistical model created by Heppner and Maynard 1987, and a more recently developed model using real-time coherent radar measurements from the SuperDARN radar network. Ionospheric simulations were run using Utah State University s Time-Dependent Ionospheric Model (TDIM) with the two …

Microscopic Analysis For Water Stressed By High Electric Fields In The Prebreakdown Regime, R. P. Joshi, J. Qian, K. H. Schoenbach, E. Schamiloglu

Bioelectrics Publications

Analysis of the electrical double layer at the electrode-water interface for voltages close to the breakdown point has been carried out based on a static, Monte Carlo approach. It is shown that strong dipole realignment, ion-ion correlation, and finite-size effects can greatly modify the electric fields and local permittivity (hence, leading to optical structure) at the electrode interface. Dramatic enhancements of Schottky injection, providing a source for electronic controlled breakdown, are possible. It is also shown that large pressures associated with the Maxwell stress tensor would be created at the electrode boundaries. Our results depend on the ionic density, and …