Biomedical Engineering and Bioengineering Commons^™

The Characterization Of Biofilm Attachment To Metal Interfaces: Effects Of Substratum Properties, Marcel D. Mendes

Master's Theses

Bacteria are among the most abundant microorganisms on earth, and can be found in essentially every environment. When a clean surface is exposed to media containing planktonic bacteria, the bacterial cells will attach to the surface and aggregate to form what is known as a biofilm. Biofilms have been shown to negatively affect many industries including medical, industrial, and food science applications. While biofilms have been well characterized from a microbiology perspective, there has been much less research from a materials science standpoint. It is hypothesized that the material properties of the substratum (such as the micro-structure) have a significant …

Viscoelastic Anisotropic Finite Element Mixture Model Of Articular Cartilage Using Viscoelastic Collagen Fibers And Validation With Stress Relaxation Data, Matthew Alexander Griebel

Master's Theses

Experimental results show that collagen fibers exhibit stress relaxation under tension and a highly anisotropic distribution. To further develop the earlier model of Stender [1], the collagen constituent was updated to reflect its intrinsic viscoelasticity and anisotropic distribution, and integrated with an existing mixture model with glycosaminoglycans and ground substance matrix. A two-term Prony series expansion of the quasi-linear viscoelastic model was chosen to model the viscoelastic properties of the collagen fibers. Material parameters were determined by using the simplex method to minimize the sum of squared errors between model results and experimental stress relaxation data of tissue in tension. …

Comparing Anti-Vegf Antibodies And Aptamers On Paper Microfluidic-Based Platforms, Katherine Noel Clayton

Master's Theses

The field of microfluidics is expanding into what is known as paper microfluidics. This uses a paper platform rather than materials (i.e. PDMS, PMMA) that are commonly used in microfluidics research. Current devices require an expensive manufacturing process and external sources to power the device. Such devices are not practical in low resource environments. As a consequence, it is the goal of this Thesis to develop a three-dimensional, multiplexed assay chip using nitrocellulose membranes. This device comprises of multiple layers of nitrocellulose membranes with defined fluidic channels. The multiple layers are bound together using double backed tape, and imbedded between …

Design Of Experimentation To Systematically Determine The Interaction Between Electrospinning Variables And To Optimize The Fiber Diameter Of Electrospun Poly (D, L-Lactide-Co-Glycolide) Scaffolds For Tissue Engineered Constructs, Yvette S. Castillo

Master's Theses

Cardiac disease causes approximately a third of the deaths in the United States. Furthermore, most of these deaths are due to a condition termed atherosclerosis, which is a buildup of plaque in the coronary arteries, leading to occlusion of normal blood flow to the cardiac muscle. Among the methods to treat the condition, stents are devices that are used to restore normal blood flow in the atherosclerotic arteries. Before advancement can be made to these devices and changes can be tested in live models, a reliable testing method that mimics the environment of the native blood vessel is needed. Dr. …

Characterization Of Raw Milk Fouling On Plate-Type Heat Exchangers Using Different Alloys And Cow Phenotypes, Stephen Ernest Nelson

Master's Theses

ABSTRACT

Characterization Of Raw Milk Fouling On Plate-Type Heat Exchangers Using Different Alloys And Cow PhenotypeS

Stephen Ernest Nelson

Milk and other dairy products are widely used in many households today. Milk is a popular beverage that is seen as a healthy alternative to other synthetic beverages such as soda pop and other sugar based drinks. It became law that milk, and milk products are pasteurized before its release to the general public (FDA 2003). Pasteurization is a thermal process where the intent is to lower the concentration of microorganisms in the milk to render it safe to drink with …

A Kinetic Study Of Anti-Vegf-A Polyclonal Antibodies And Anti-Vegf-A Ssdna Aptamers, Heather A. Hedeen

Master's Theses

A new detection reagent that could possibly augment or replace antibodies research and diagnosis methods are aptamers. Aptamers are ssDNA, RNA or polypeptide constructs that function like active antibodies. Antibodies and aptamers both specifically bind to selected target molecules, and as such they enable the detection or targeting of the presence or absence of a specific antigen.

In order to ensure that ssDNA aptamers perform similarly to antibodies, anti-VEGF-A polyclonal antibody and anti-VEGF-A ssDNA aptamer were evaluated against vascular endothelial growth factor A (VEGF-A) using Surface Plasmon Resonance (SPR). It was hypothesized that the anti-VEGF-A aptamer had the same, if …

Effects Of Ovariectomy, Seasonal Changes, And Anatomical Position On The Compact Bone Remodeling As Seen In The Adult Ovine Model, Erica Wong

Master's Theses

The purpose of this study is to characterize the compact bone remodeling of the ovariectomized ewe and its effectiveness as an animal model for studies of postmenopausal osteoporosis. The use of animal models is a beneficial way to evaluate the effectiveness of medical devices and therapeutic agents for treating diseases. The ovine model is an attractive option because of its large size and similar bone remodeling to humans. However, this species, like most animals, does not undergo a natural menopause, making an ovariectomy necessary for studies of estrogen depletion. The OVX (ovariectomized) sheep has been widely accepted as a model …

Nitrocellulose Paper Based Microfluidic Platform Development And Surface Functionalization With Anti-Ige Aptamers, Jennifer Guerin Ward

Master's Theses

The purpose of this thesis project was to demonstrate the ability to utilize the capabilities of aptamers so that they may act as capture reagents for paper microfluidic devices. Several characterization experiments were conducted as a precursor before the final experimentation was performed. Paper characterization, manufacturing protocols for printing and heating, as well as 3D chip fabrication were all performed and analyzed. The results confirmed that the control of fluid through a 3D microfluidic device based in nitrocellulose is possible.

For the biochemistry portion of this thesis report, antibodies and aptamers were chosen to react with IgE, an antibody that …

Impedance Sensing Of N2a And Astrocytes As Grounds For A Central Nervous System Cancer Diagnostic Device, Fraser Traves Smith Grove

Master's Theses

This thesis utilizes previously described manufacturing and design techniques for the creation of a PDMS-glass bonded microfluidic device, capable of electrochemical impedance spectroscopy (EIS). EIS has been used across various fields of research for different diagnostic needs. The major aim of this thesis was to capture cancerous and non-cancerous cells between micron sized electrodes within a microfluidic path, and to complete analysis on the measured impedances recorded from the two differing cell types. Two distinct ranges of impedance frequency were analyzed – the α dispersion range, which quantifies the impedance of the membranes of the cells of interest, and the …

Preparation And Characterization Of Electrospun Poly(D, L-Lactide-Co-Glycolide) Scaffolds For Vascular Tissue Engineering And The Advancement Of An In Vitro Blood Brain Barrier Model, Deven Chandrakant Patel

Master's Theses

Developing an in vitro Blood Brain Barrier model that will replicate the physiological, anatomical, and functional characteristics of the native BBB has gained significant attention. Such a model would enable prediction of the penetration of CNS targeting drug candidates across the BBB, allow pre-screening and optimization strategies to be developed for new drugs and gene delivery formulations, and permit research groups to further understand how a dysfunctional BBB is involved in the pathogenesis of several neurological diseases.

The Tissue Engineering laboratory at the California Polytechnic State University, San Luis Obispo is currently in the process of developing a dynamic in …

Development And Characterization Of Phospholipid Encapsulated Quantum Dot Constructs For Biologic Applications, Laura C. Sparks

Master's Theses

DEVELOPMENT AND CHARACTERIZATION OF PHOSPHOLIPID ENCAPSULATED QUANTUM DOT CONSTRUCTS FOR BIOLOGIC APPLICATIONS

The American Cancer Society predicts that 577,190 cancer-related deaths and 1,638,910 newly diagnosed cases of cancer will occur in 2012. As these statistics show, cancer is a prevalent and devastating health issue; determined by the Mayo Clinic to be the second leading cause of death in the United States. Skin cancer is the most common form of cancer in the United States. In 2012 more than 68,000 Americans will be diagnosed with melanoma, 48,000 will be diagnosed with an early form of the disease that has not yet …

A Stochastic Simulation Model Of Alarm Response Strategies On A Telemetry Floor, Tasneem M. Pishori

Master's Theses

The large quantity of alarms characteristic of clinical settings have resulted in nursing staff suffering from a phenomenon termed ‘alarm fatigue’. Alarm fatigue is desensitization via habituation – as these commonly heard noises cause caregivers to have delayed or no response to alarms. Alarm management was ranked number one on the annual top ten list of technology hazards afflicting healthcare institutions published by the ECRI Institute for 2012. Several patient safety organizations have established alarm fatigue as a priority concern, and are working to eradicate the issue from the healthcare environment by 2017. To better understand the problem, a simplified …

Development And Application Of A Portable System To Reliably Measure Grip Forces Using Thin-Film Force Sensors, Shane Vincent Tornifoglio

Master's Theses

Accurate tracking of hand grip force is an important consideration needed for a robust understanding in the study of human biomechanics. One aspect where it proves useful is in hand-arm vibration, such as from gripping a power tool. Depending on how firmly the user is gripping the tool, they may change their exposure levels to the tool vibration, which can lead to potential disorders such as Hand-Arm Vibration Syndrome (HAVS).

A small, battery powered portable force unit has been developed to supply power to, and condition, the signals from eight thin-film force sensors. This gives a better understanding of the …

A Comprehensive Methodology For Assessing Biomechanical Risks Associated With Hand Tool Use: Applied To Laparoscopic Surgical Instruments, Drew R. Seils

Master's Theses

Biomechanical risk factors are physical stressors that act on the neuromuscular structures of the human body and are present in all occupational settings. Repetition and intensity of tasks performed can magnify the effects of the biomechanical risks that a worker is exposed to.

After reviewing the current literature on ergonomics in laparoscopic surgery it was clear that a comprehensive approach to quantitatively reporting on the biomechanical risk factors associated with surgical hand tools had never been performed. Utilizing an opto-electronic motion capture system meant the exact surgeon posture was recorded during simulated surgical tasks. Electromyography was used to evaluate muscle …

Mechanical Properties Of Bone Due To Sost Expression: A 3-Point Bending Assessment Of Murine Femurs, Kainoa John Peterson

Master's Theses

Sclerostin, a protein coded for by the SOST gene, is an osteocyte-expressed negative regulator of bone formation. The absence of SOST in the genome may have an effect on bone formation both during skeletal maturation and full maturity. This study attempts to determine significant differences in the mechanical properties of bone that expresses SOST compared to bone that does not. One hundred femur samples from 6, 8, and 12 month old mice were obtained from Lawrence Livermore National Labs and loaded until failure using three-point bending. Results showed significant differences in treatment group effects for cross sectional area, yield force, …

Detection Of Sk2 Channels On Hippocampal Neurons, Jamie L. Maciaszek

Master's Theses

Calcium-activated small conductance potassium channels (SK) are crucial for synaptic plasticity, sleep, and learning and memory (Hammond, Bond et al. 2006; Cueni, Canepari et al. 2008; Lin, Lujan et al. 2008). Despite the recent progress on SK channel physiology, the precise spatial organization of SK channels in neurons has remained unknown. Such knowledge is critical as the subcellular distribution of SK channels is an important determinant of neuronal excitability. Currently, there are no techniques to image ion channel distribution quantitatively at the nanometer scale in living cells. Here, it is demonstrated that integration of natural toxins with single molecule atomic …

The Impact Of Increased Collateral Flow On Transverse Arteriolar Microvascular Tree Morphology, David Danzeiser

Master's Theses

The goal of this study was to understand how arteriogenesis impacts transverse arteriolar tree structure. The previous process involved a vascular casting technique that utilized black India ink as the casting agent and manual measurement of vessel morphology with ImageJ. This study decreased the complexity of the casted samples by using a casting compound called Microfil. Microfil’s viscosity can be adjusted and through experimentation, a viscosity was found that stopped at the capillary level, allowing only the arterial side of the circulation to be casted. A macro in ImageJ was written to help with morphological measurement by bundling vessel length …

Dc Dielectrophoretic Assisted Anti-Fouling Filtration System, Nathan M. Cohen

Master's Theses

Filtration processes, whether on the microfluidic, clinical treatment systems, or industrial scale (e.g., point-of-care diagnostics, dialysis, and biopharmaceutical manufacturing, respectively), are often inseparable from membrane clogging (fouling). As a consequence, most, if not all, filtration systems require frequent maintenance to maintain functionality and efficiency. The thesis of this project hypothesizes that Dielectrophoresis can be combined with standard filtration to reduce filter fouling, extending membrane life, and enabling continuous operation. This project investigates a method to reduce fouling, add specificity and efficiency, and decrease the cost and challenge of filtration based biofluid separations.

To substantiate this thesis, we designed, fabricated, and …

Development Of A Standardized Method For Comparing Biomechanical Properties Of Various Sternal Closure Techniques, Ramzi P. Hawit

Master's Theses

Background:

33.6% of all deaths in America are caused by cardiovascular disease. An estimated 82.6 million adults (>1 in 3) in America have some form of cardiovascular disease. There were over 400,000 bypass surgeries requiring open-heart surgery. Sternal dehiscence is associated with a morbidity rate of over 47% if mediastinitis supervenes. A rigid closure is required to avoid healing complications, and wire, plates, and bands are all used in an attempt to make a better closure. The purpose of this study it to compare multiple closures and validate a new testing method.

Methods:

Polyurethane foam blocks will be used, …

Second Generation Data-Logging System For Long-Duration Field Measurement Of Vibration Exposure And Grip Force, Robert H. Knapp Iii

Master's Theses

Millions of United States workers are exposed to vibration at their job, whether it is from a power tool that causes hand and arm vibration or from heavy machinery. These vibrations are known to result in physical disorders such as Hand-Arm Vibration Syndrome, which can be debilitating to the point where workers can no longer do their job effectively. Research groups have taken an interest in finding what vibration characteristics are most harmful and choose to record vibration information using data-logging devices. Often, many devices, whether they are commercial or custom-built devices, use frequency weightings and full day estimations to …

Impedance-Based Detection Of Tissue Using A Multi-Electrode Device, Shane Killian Fleshman

Master's Theses

Melanoma skin cancer is the abnormal growth of the melanocytes – the pigmented cells located in the epidermis. The current gold standard diagnostic technique for determining whether a lesion is cancerous involves subjectively examining suspicious lesions and performing an invasive biopsy to confirm melanoma. This method may neglect some lesions or cause scarring from biopsies that turn out to be benign. Thus, impedance-based detection using a multi-electrode device was investigated as a noninvasive technique to diagnose melanoma skin cancer. The multi-electrode device was designed with 8 equally spaced Ag/AgCl electrodes surrounding one central electrode at a 5 mm radius. The …

Implementation Of Medicinal Leech Preparation To Investigate The Connection Between The Motor Neuron And Muscle Fiber Via Sharp Electrode Electrophysiology, Chandra Nikole Miller

Master's Theses

There are forty registered organophosphates in the United States and they range from pesticides and insecticides to nerve agents or neurotoxins such as sarin. Organophosphates (OP’s) have been used in chemical warfare for years and tend to lead to death due to an attack on the nervous system. Chemical assays and mass microscopy have been used to assess the concentration of OP’s in the environment, but both methods require the body to metabolize the OP first, which can be detrimental to the victim. It is crucial to come up with a method to investigate and detect these neurotoxins without causing …

Impact Of Collateral Enlargement On Smooth Muscle Phenotype, Alexander Jerome Bynum

Master's Theses

Peripheral Artery Disease is a very serious disease characterized by an arterial occlusion due to atherosclerotic plaques. In response to an arterial occlusion, arteriogenesis occurs, causing smooth muscle cells to transition from a contractile to synthetic state. Also following an arterial occlusion, functional impairment was seen in the collateral circuit. An immunofluorescence protocol was developed in order to assess the impact of collateral enlargement (arteriogenesis) on smooth muscle phenotype at various time points. Smooth muscle α-actin was used to mark all smooth muscle cells, Ki-67 was used to label proliferating smooth muscle cells, and a fluorescent nuclear stain was used …

Seasonal And Anatomical Variation In Compact Bone Remodeling In The Adult Sheep, Joseph Calcagno

Master's Theses

ABSTRACT

SEASONAL AND ANATOMICAL VARIATION IN COMPACT BONE REMODELING IN THE ADULT SHEEP

Joseph Calcagno

In order to determine whether ovine compact bone is suitable for study of osteoporosis, the remodeling parameters of the untreated animal must be fully characterized. Ovine compact bone is an attractive large animal model due to its similarities in size and bone remodeling to humans. However hormonal, exercise, and dietary changes due to seasonal changes can cause treatment effects to be hidden or superimposed on existing changes in the bone. In order to determine if any seasonal or anatomical variation occurred in the compact bone …

Protective Effects Of Milk Phospholipids Against Uv Photodamage In Human Skin Equivalents, Zyra Achay

Master's Theses

The ultraviolet (UV) spectrum has been known to cause damage to skin in varying degrees. UVB radiation (290-320 nm) in particular, has been proven to be highly mutagenic and carcinogenic in many animal experiments compared to either UVA or UVC. The alarming rate of increase in skin cancer incidence has prompted many investigators to pursue other alternatives to sunscreens including changes in lifestyle habits and dietary consumption in order to boost our efforts in tackling this widespread disease. Previous studies employing confocal reflectance, MTT assay and histology suggest that milk phospholipids may possess protective properties against UVB-mediated damage but the …

Effect Of Prostaglandin E2 On Mechanical Stresses Applied By Mc3t3-E1 Osteoblast-Like Cells On A Soft Hydrogel Substrate, Abhijit Deb Roy

Master's Theses

Osteoblasts are sensitive to mechanical stimuli and release Prostaglandin E2 (PGE2) when exposed to a fluid shear stress. The exact mechanism by which these cells sense mechanical stress is not well established. A study of the stresses applied by the osteoblasts, under the influence of PGE2, on a hydrogel provided information regarding intercellular-communication via changes in the substrate surface pattern.

A digital image correlation program was developed using the Levenberg-Marquardt optimization algorithm to analyze images and compare the deformations between pairs of images. Comparisons of images before and after the addition of PE2 to the media showed differences in the …

Automation Of Orthodontic Wire Tester For Performing Three Point Bending Tests, Adithya Venkatesan

Master's Theses

Abstract

Understanding the biomechanical factors in orthodontics is important in order to improve the overall effectiveness of actual clinical treatment. An accurate method to study the threedimensional (3D) force systems and the resulting movements of teeth during orthodontic treatment is needed along with the understanding of the material properties of any orthodontic wire. Until recently, most of the orthodontic biomechanics literature was limited to twodimensional experimental studies. Recent advances in threedimensional computer modeling have also been developed but have been limited to the manual control of tooth movement. Overall, there is very little published evidence in the literature on the …

Glucose Biosensor Using Electrospun Mn2o3-Ag Nanofibers, Shan Huang

Master's Theses

The highly porous Mn₂O₃-Ag nanofibers were fabricated by a facile two-step procedure (electrospinning and calcination) and then employed as the immobilization matrix for glucose oxidase (GOD) to construct an amperometric glucose biosensor. A notable enhancement of direct electron transfer between GOD and the electrode is observed at the Mn₂O₃-Ag-GOD modified electrode with a fast electron transfer rate constant. The biosensor also shows fast response to glucose, high sensitivity (40.60 μA×mM^-1×cm^-2), low detection limit (1.73 µM at S/N=3), low K_m,app value and excellent selectivity. These results indicate that …

Ros-Drill Automation: Visual Feedback Control And Rotational Motion Tracking, Jhon F. Diaz

Master's Theses

ICSI (intra-cytoplasmic sperm injection) has attracted research interest from both biological and engineering groups. The technology is constantly evolving to perform this procedure with precision and speed. One such development is the contribution of this thesis. We focus on a relatively recent procedure called Ros-Drill^© (rotationally oscillating drill), of which the early versions have already been effectively utilized for the mice. In the first part, we present a procedure to automate a critical part of the operation: initiation of the rotational oscillation, Visual feedback is used to track the pipette tip. Predetermined species-specific penetration depth is successfully utilized …

Characterizing Nerve Fiber Activation By Varying Fiber Diameter And Depth Within A Conductive Medium: A Finite Element Approach, Nathan Daniel Soto

Master's Theses

In some instances neuropathies can be diagnosed through a conduction velocity test. However, not all neuropathies can be classified using this method. Gaining an understanding of how the stimulus level varies for different fiber sizes at different fiber depths within a conductive medium will provide useful information for simulation studies.

Following a two-step approach using COMSOL and MATLAB, a simulation was implemented to investigate the stimulus necessary to activate different sized fibers at different depths. In this two-step approach, COMSOL was used to describe the voltage profile that would be present within a conductive medium after a stimulus was applied. …