Biomedical Engineering and Bioengineering Commons^™

Real-Time Bio Sensing Using Micro-Channel Encapsulated Mems Resonators, Ayesha Iqbal

Electronic Theses and Dissertations

This work presents a label-free bio-molecular detection technique based on realtime monitoring of the resonant frequency of micromechanical thermal-piezoresistive rotational mode disk resonators encapsulated in microfluidic channels. Mass loading via adsorption of molecular layers on the surface of such devices results in a frequency shift. In order to provide a reliable platform for sample-resonator interactions and to protect the resonators from contaminants, the resonators were encapsulated in PDMS-based microfluidic channels. Micro-channel encapsulation also allows insulation of electrical signals from the analyte solution. To characterize the performance of such devices as real-time label-free bio-molecular detectors, the strong non-covalent binding of Avidin …

Investigating Hemodynamic Responses To Electrical Neurostimulation, Sean Youra

Master's Theses

Since the 1900s, the number of deaths attributable to cardiovascular disease has steadily risen. With the advent of antihypertensive drugs and non-invasive surgical procedures, such as intravascular stenting, these numbers have begun to level off. Despite this trend, the number of patients diagnosed with some form of cardiovascular disease has only increased. By 2030, prevalence of coronary heart disease is expected to increase approximately by 18% in the United States. By 2050, prevalence of peripheral arterial occlusive disease is expected to increase approximately by 98% in the U.S. No single drug or surgical intervention offers a complete solution to these …

A Rubric For Electrochemical Testing Of Metallic Biomaterials, Frederick G. De La Fuente

Master's Theses

Corrosion is a major factor for the failure of metallic medical implants. Testing a metal’s suseptability to corrosion prior to implantation is key to a successful implantation. Electrochemical processes were used in this study to evaluate the characteristics of corrosion of both AISI 316 stainless steel and titanium alloy Ti6Al4V, welded and non-welded. Linear, potentiodynamic, and cyclic polarization curves were produced by the PARC 2273 potentiostat showing the corrosion tendencies of the metals in four unique solutions 3.5% NaCl, 0.35% NaCl, phosphate buffered saline solution (PBS), and Butterfield phosphate buffered solution (BPS). The concentration of chloride ions in solutions affected …

Design, Characterization And Application Of A Multiple Input Stethoscope Apparatus, Spencer Geng Wong

Master's Theses

For this project, the design, implementation, characterization, calibration and possible applications of a multiple transducer stethoscope apparatus were investigated. The multi-transducer sensor array design consists of five standard stethoscope diaphragms mounted to a rigid frame for a-priori knowledge of their relative spatial locations in the x-y plane, with compliant z-direction positioning to ensure good contact and pressure against the subject’s skin for reliable acoustic coupling. When this apparatus is properly placed on the body, it can digitally capture the same important body sounds investigated with standard acoustic stethoscopes; especially heart sounds. Acoustic signal inputs from each diaphragm are converted to …

Upper Extremity Biomechanics Of Children With Spinal Cord Injury During Wheelchair Mobility, Alyssa J. Schnorenberg, Brooke A. Slavens, Adam Graf, Joseph J. Krzak, Lawrence C. Vogel, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

While much work is being done evaluating the upper extremity joint dynamics of adult manual wheelchair propulsion, limited work has examined the pediatric population of manual wheelchair users. Our group used a custom pediatric biomechanical model to characterize the upper extremity joint dynamics of 12 children and adolescents with spinal cord injury (SCI) during wheelchair propulsion. Results show that loading appears to agree with that of adult manual wheelchair users, with the highest loading primarily seen at the glenohumeral joint. This is concerning due to the increased time of wheelchair use in the pediatric population and the impact of this …

Platform Technologies To Advance Clinically Relevant Tissue Engineered Heart Valve Products, Leslie Neil Sierad

All Dissertations

Diseased heart valves are commonly replaced by mechanical, bioprosthetic, or allograft heart valves. These replacements provide major improvements in cardiac function and quality of life, but have significant limitations and eventually require surgical replacement within 15-20 years. These risks are particularly prominent in pediatric patients and young adults. The field of tissue engineering and regenerative medicine, which combines scaffolds and cells, holds great promise in developing living replacement heart valves that would self-repair and grow in size along with the growing children.

The long-term goal of this project is to generate living, tissue-engineered heart valves from biological scaffolds and autologous …

Self-Assembly Of Gold Nanosphere Dimers By Inertial Force, George Andrew Christopher Sakhel

Graduate Theses and Dissertations

The morphology and composition of a nanoparticle (NP) play a critical role in determining the NP's properties and function. To date, researchers have created a myriad of NPs of different shapes, sizes, and compositions with interesting attributes and applications ushering a revolution in medicine, electronics, microscopy, and microfluidics.

In this study, gold (Au) nanosphere dimers (NSDs) have been synthesized through a novel self-assembly method. These particles were created from Au NPs mono-dispersed in aqueous solution via a process of centrifugation and capping agent replacement. Au NSDs consist of two Au NPs combined together with minimal gaps between them. Optical spectral …

A Novel Cell Based Assay For Mmp Inhibitor Screening, Pantrika Krisanarungson

Graduate Theses and Dissertations

Up to date, a plethora of protein based materials are used as implants to stimulate tissue regeneration or fillers to alleviate tissue or organ impairment. This includes glottal insufficiency, urinary bladder incontinence and especially in cosmetic industrial to improve facial contour. Once in vivo, protein-based materials are decomposed by cell secreted matrix metalloproteinases (MMP) and lose their volume within months. By introducing MMP inhibitor (MMPI), the extent of material degradation over time may be reduced. In this dissertation, the development of cell-based assay capable of identifying MMPI candidates for protein-based implant lifetime prolongation is described. To visualize the degradation, DQ-gelatin, …

Microvascular Topology And Intravascular Endothelial Cell Labeling In The Gracilis Anterior Muscle Of Balb/C Mice, Paul Heckler Ii

Biomedical Engineering

Peripheral arterial occlusive disease (PAOD) affects approximately 200 million individuals globally. The major underlying cause of PAOD is an inflammatory disease known as atherosclerosis, which results from the build-up of low-density lipoproteins (LDL) in the sub-intimal space. This initiates a complex cascade of events that lead to plaque growth. Plaque growth can then expand into the lumen of the vessel and result in occlusion and/or thrombosis. Symptoms of the disease can include claudication, ulcers, and/or gangrene, although many patients are asymptomatic. Similar to other forms of ischemic disease, risk factors for PAOD include hypertension, diabetes, and smoking. Common treatments include …

Development Of Poly(Lactic Acid)-Poly(Ethylene Glycol) Nanoparticles For The Delivery Of Non- Toxic Drug In Combination Therapy For The Treatment Of Glioblastoma And Neuroblastoma, Olivia Grace Decroes

All Theses

Glioblastoma and neuroblastoma are both solid-form tumors. Glioblastomas primarily reside in the brain, while neuroblastomas are found in the sympathetic nervous system. Both glioblastoma and neuroblastoma re classified as orphan diseases, which affect less than 200,000 individuals a year. Over the course of 5 years, 40% of patients diagnosed with neuroblastomas and only 6% of patients diagnosed will glioblastomas will be living.^73,74. Glioblastoma and neuroblastoma tumors possess a gene known as MGMT. MGMT is used by tumors as a DNA repair mechanism, which increases the likelihood these tumors will become resistant to traditional drug therapies.^28,37 Other pathways, …

Cfd Simulation Of The Thermal Performance Of A Parallel Counter-Parallel Flow Heat Exchanger For The Treatment Of Hypothermia, Alex Heller

UNLV Theses, Dissertations, Professional Papers, and Capstones

Hypothermia is a life-threatening condition. Currently, active warming methods are the most effective treatment for dysthermic patients. The aim of this study is to investigate the use of computational fluid dynamics (CFD) in evaluating the thermal performance of a parallel/counter-parallel flow heat exchanger used as part of a fluid warmer to treat Hypothermia. The 3D model of the heat exchanger is divided into three regions; Infusate (fluid to be heated), Hot Water (heating fluid), and a Solid Region (wall). At the end of the heat exchanger, an elbow section is used to create the counter-parallel flow arrangement specific to this …

Design Of The High-Speed Stereo Radiography System, John C. Ivester Iv

Electronic Theses and Dissertations

Orthopaedic pathologies often involve disruption of the mechanical environment of a joint at/below the mm scale. The ability to measure biomechanical kinematics at the sub-mm scale is essential for obtaining valuable insight into pathologies, but small motions of the joints are difficult to quantify. Estimates of skeletal kinematics are commonly made from optical motion capture systems and markers placed on the skin. The error caused by external marker movement is largely avoided with x-ray motion capture. Dynamic radiography uses a series of x-ray images recorded at high-speed and captures in-vivo joint motion. Uncovering the mechanical foundation of orthopaedic pathologies requires …

Impedance Biosensors For The Rapid Detection Of Viral And Bacterial Pathogens Using Avian Influenza Virus Subtypes H5n1 And H7n2 And Escherichia Coli O157:H7 As Model Targets, Jacob David Lum

Graduate Theses and Dissertations

This research investigated impedance biosensors for the rapid detection of viral and bacterial pathogens using avian influenza virus (AIV) subtypes H5N1 and H7N2 and Escherichia coli O157:H7 as the model targets, which were chosen due to their impact on the agricultural and food industries. For the detection of AIV H7N2, a single stranded DNA aptamer was selected using systematic evolution of ligands by exponential enrichment (SELEX). The selected aptamer and a previously selected aptamer against AIV H5N1 were used in a microfluidics chip with an embedded interdigitated array microelectrode to fabricate an impedance biosensor for specific detection of AIV H7N2 …

Fluid Powered Miniature In Vivo Robots For Minimally Invasive Surgery (Mis), Abolfazl Pourghodrat

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Minimizing the invasiveness of surgery is believed to improve patient outcomes. Bleeding, infection, and pain are major concerns in surgery afflicting patients for decades. Minimally invasive techniques have come into play to reduce these concerns and smooth the evolution of abdominal surgery to a scarless process where nearly all surgeries can be performed without a skin incision. Technology continually advances the frontier of development of novel surgical devices to implement less invasive surgical techniques.

Fusion of robotics and Minimally Invasive Surgery (MIS) has created new opportunities to develop diagnostic and therapeutic tools. Surgical robotics is advancing from externally actuated systems …

Construction Of 3d Biomimetic Tissue Niches For Directing Pancreatic Lineage Differentiation Of Human Embryonic Stem Cells, Weiwei Wang

Graduate Theses and Dissertations

The potential of human embryonic stem cells (hESCs) to differentiate into insulin producing beta cells offers great hope for cell-based therapy for diabetes treatment. However, in vitro pancreatic differentiation of hESCs remains challenging. In the past decade, most protocols for differentiating pancreatic cells have been focused on the use of signaling molecule cocktails on 2D substrates. Studies on embryonic development biology strongly suggest that extracellular matrix (ECM) plays a critical role on hESCs behavior. In this work, we first established a 3D collagen scaffold culture system for hESCs differentiating into definitive endoderm (DE), which is the first and most important …

Improving Golf Putt Performance With Statistical Learning Of Eeg Signals, Qing Guo

Graduate Theses and Dissertations

In this thesis, a machine learning based method is proposed to predict the putt outcomes of golfers based on their electroencephalogram (EEG) data. The method can be used as a core building block of a brain-computer interface, which is designed to provide guidance to golf players based on their EEG patterns. The proposed method includes three steps. First, multi-channel 1-second EEG trials were extracted during golfers' preparation of putting. Second, different features are calculated such as correlation coefficient, power spectrum density and coherence, which are used as features for the classification algorithm. To predict golfers' performance, the support vector machine …

Experimental Terahertz Imaging And Spectroscopy Of Ex-Vivo Breast Cancer Tissue, Tyler C. Bowman

Graduate Theses and Dissertations

This thesis presents experimental results of terahertz imaging and spectroscopy techniques to analyze excised breast cancer tissue. The pulsed terahertz system at the University of Arkansas was used to assess formalin-fixed, paraffin-embedded breast cancer tissue obtained from 22, 40, and 46 year old patients. The tissue for this research was sliced to relatively thin sections of 10 μm thick and mounted on glass slides. Terahertz reflection time and frequency domain images of the breast cancer tissue were then obtained and compared to histopathology slides from the same patient. Results showed good correlation between the reflection images and histopathology slides for …

The Reliability Of Parafoveal Cone Density Measurements, Benjamin S. Liu, Sergey Tarima, Alexis D. Visotcky, Alex Pechauer, Robert F. Cooper, Leah Landsem, Melissa A. Wilk, Pooja Godara, Vikram Makhijani, Yusufu N. Sulai, Najia Syed, Galen Yasumura, Anupam K. Garg, Mark E. Pennesi, Brandon J. Lujan, Alfredo Dubra, Jacque L. Duncan, Joseph Carroll

Biomedical Engineering Faculty Research and Publications

Background Adaptive optics scanning light ophthalmoscopy (AOSLO) enables direct visualisation of the cone mosaic, with metrics such as cone density and cell spacing used to assess the integrity or health of the mosaic. Here we examined the interobserver and inter-instrument reliability of cone density measurements.

Methods For the interobserver reliability study, 30 subjects with no vision-limiting pathology were imaged. Three image sequences were acquired at a single parafoveal location and aligned to ensure that the three images were from the same retinal location. Ten observers used a semiautomated algorithm to identify the cones in each image, and this was repeated …

Nerve Fiber Diameter Measurements Using Hematoxylin And Eosin Staining And Brightfield Microscopy To Assess The Novel Method Of Characterizing Peripheral Nerve Fiber Distributions By Group Delay, Jorge Arturo Vazquez

Master's Theses

Peripheral neuropathies are a set of common diseases that affect the peripheral nervous system, causing damage to vital connections between various parts of the body and the brain and spinal cord. Different clinical conditions are known to selectively impact various size nerve fibers, which often makes it difficult to diagnose which peripheral neuropathy a patient might have. The nerve conduction velocity diagnostic test provides clinically useful information in the diagnosis of some peripheral neuropathies. This method is advantageous because it tends to be minimally invasive yet it provides valuable diagnostic information. However, this test does not determine characteristics of peripheral …

Non-Common Path Aberration Correction In An Adaptive Optics Scanning Ophthalmoscope, Yusufu N. Sulai, Alfredo Dubra

Biomedical Engineering Faculty Research and Publications

The correction of non-common path aberrations (NCPAs) between the imaging and wavefront sensing channel in a confocal scanning adaptive optics ophthalmoscope is demonstrated. NCPA correction is achieved by maximizing an image sharpness metric while the confocal detection aperture is temporarily removed, effectively minimizing the monochromatic aberrations in the illumination path of the imaging channel. Comparison of NCPA estimated using zonal and modal orthogonal wavefront corrector bases provided wavefronts that differ by ~λ/20 in root-mean-squared (~λ/30 standard deviation). Sequential insertion of a cylindrical lens in the illumination and light collection paths of the imaging channel was used to compare image resolution …