Biomedical Engineering and Bioengineering Commons^™

Extended-Use Ecg Monitor, Daniel Aaron Soski

Master's Theses

In this thesis, a prototype ECG monitor was developed that is integrated into an elastic shirt and takes a 3-lead ECG for over 5 days. The high-quality measurements can be used to identify markers indicative of various detrimental heart conditions. Measurements recorded by the device are encrypted and stored onto a micro-SD card. Current Holter monitors are expensive and have functional lives less than 48 hours; however, extended duration monitoring has been proven more useful in diagnosis. The device designed demonstrates that ECG measurements can be taken over longer durations without sacrificing quality, comfort, or device cost.

Preparation Of Supramolecular Amphiphilic Cyclodextrin Bilayer Vesicles For Pharmaceutical Applications, Kate E. Frischkorn

Master's Theses

Recent pharmaceutical developments have investigated using supramolecular nanoparticles in order to increase the bioavailability and solubility of drugs delivered in various methods. Modification of the carbohydrate cyclodextrin increases the ability to encapsulate hydrophobic pharmaceutical molecules by forming a carrier with a hydrophobic core and hydrophilic exterior. Guest molecules are commonly added to these inclusion complexes in order to add stability and further increase targeting abilities of the carriers. One such guest molecule is adamantine combined with a poly(ethylene glycol) chain. Vesicles are formed by hydrating a thin film of amphiphilic cyclodextrin and guest molecules in buffer solution that mimics physiological …

Neuro-Silicon Interface Of A Hirudo Medicinalis Retzius Cell Integrated With Field Effect Transistor, Kurt Christian Sjoberg

Master's Theses

The focus of this thesis was to measure the intracellular voltage of a living neural cell using a silicon transistor. The coupling of neurological tissues with silicon devices is of interest to the fields of neurology, neuroscience, electrophysiology and cellular biology. In previous work by Peter Fromherz, single neurons were successfully coupled to transistors [1]. This thesis aims to show proof of concept of the fabrication of a simple neuro-silicon interface using wafer processing methods currently available at Cal Poly. The types of transistors and cells used, the methods for dissecting and preparing the cells, the electrophysiology methods for validating …

Characterization Of Arterial Flow For Junctional Bleeding Control, Nick Bosio

Master's Theses

This study investigated reducing volumetric flowrate under steady flow conditions by varying lengths of compression with constant cross-sectional area and varying cross-sectional area reduction with constant length in order to better understand how to control junctional hemorrhaging. The hypotheses of this study were that length reduction will have little effect on volumetric flowrate and that cross-sectional area reduction would need to be approximately 80 percent in order to obtain bleeding control. The study found that length reduction has little effect on changing the flowrate. However, in order to obtain at least 80 percent reduction in flow, the area needs to …

Validation Of A 1d Algorithm That Measures Pulse Wave Velocity To Estimate Compliance In Blood Vessels, James Leung

Master's Theses

The purpose of this research is to determine if it is possible to validate the new 1D method for measuring pulse wave velocity in the aorta in vivo and estimate compliance. Arterial pressure and blood flow characterize the traveling of blood from the heart to the arterial system and have played a significant role in the evaluation of cardiovascular diseases. Blood vessel distensibility can give some information on the evolution of cardiovascular disease. A patient’s aorta cannot be explanted to measure compliance; therefore we are using a flow phantom model to validate the 1D pulse wave velocity technique to estimate …

Comparative Analysis Of Physiological Measurements And Environmental Metrics On Predicting Heat Stress Related Events, Mckenzie Lee Barlow

Master's Theses

Exposure to high heat and humidity can lead to serious health risks, including heat exhaustion and heat stroke. Wet Bulb Globe Temperature (WBGT) and heat index have historically been used to predict heat stress events, but individualized factors are not included in the measurement. It has been shown that there is a relationship between cardiovascular measurements and heat stress, which could be used to measure heat stress risk on an individual level. Research has been done to find relationships between cardiovascular metrics in a workplace environment, however the study did not include the use of a controlled environment as a …

Eeg Characterization During Motor Tasks That Are Difficult For Movement Disorder Patients, Adam Joshua Aslam

Master's Theses

Movement disorders are a group of syndromes that often arise due to neurological abnormalities. Approximately 40 million Americans are affected by some form of movement disorder, significantly impacting patients’ quality of life and their ability to live independently. Deep brain stimulation (DBS) is one treatment that has shown promising results in the past couple decades, however, the currently used open-loop system has several drawbacks. By implementing a closed-loop or adaptive DBS (aDBS) system, the need for expensive parameter reprogramming sessions would be reduced, side-effects may be relieved, and habituation could be avoided. Several biomarkers, for example signals or activity derived …

Interfacing A Hirudo Medicinalis Retzius Cell With Insulated Gate Of Mosfet, Rachel M. Smith

Master's Theses

Much work has been done to study the external stimulation of nervous tissue as well as the transmission of neural signals to electronics. Peter Fromherz was one of the pioneers in this area of electrophysiology, with a series of experiments in the 1990s that aimed to characterize and optimize the interface between neural tissue and transistors. In this thesis, Kurt Sjoberg and I interfaced a Retzius cell isolated from a Hirudo medicinalis ganglion with the insulated gate of a MOSFET. The goal was to see change in membrane potential that could be related Fromherz’s original 1991 work. Our experimental setup …

Sex Differences In Collateral Remodeling Following Hindlimb Arterial Occlusion, Laura Burckhardt

Master's Theses

Clinical evidence indicates a higher incidence of peripheral arterial occlusive disease and associated likelihood of critical limb ischemia in women, as well as worse prognosis and decreased survival post myocardial infarction. Therefore, understanding the possible differences in underlying vascular compensation mechanisms is crucial. With arterial occlusions, necrosis and tissue injury can be naturally mitigated by the collateral circulation, improving patient prognosis. Previous sex-comparison studies describing differences in vascular remodeling are inconsistent. Therefore, the aim of this study was to describe the effect of arterial occlusion on collateral remodeling in healthy male and healthy reproductive-stage female mice. At 7 days following …

Computer-Aided Diagnoses (Cad) System: An Artificial Neural Network Approach To Mri Analysis And Diagnosis Of Alzheimer's Disease (Ad), Berizohar Padilla Cerezo

Master's Theses

Alzheimer’s disease (AD) is a chronic and progressive, irreversible syndrome that deteriorates the cognitive functions. Official death certificates of 2013 reported 84,767 deaths from Alzheimer’s disease, making it the 6th leading cause of death in the United States. The rate of AD is estimated to double by 2050. The neurodegeneration of AD occurs decades before symptoms of dementia are evident. Therefore, having an efficient methodology for the early and proper diagnosis can lead to more effective treatments.

Neuroimaging techniques such as magnetic resonance imaging (MRI) can detect changes in the brain of living subjects. Moreover, medical imaging techniques are the …

Sex Differences And The Effects Of Exercise Training On Functional Vasodilation Following Arterial Occlusion In The Balb/C Mouse Spinotrapezius, Britta Nelson

Master's Theses

Peripheral arterial occlusive disease (PAOD) often presents as intermittent claudication, which may be caused by impaired vasodilation. Impairment of resistance vessels may contribute to the pathogenesis of PAOD, and explain the poor correlation between resting blood flow and limb function. Collateral function following arterial occlusion is not well defined, however collaterals and arterialized collateral capillaries (ACCs) in male and female animal models exhibit impaired vasodilation following arterial occlusion, which can potentially be improved with exercise training. Furthermore, resistance vessels in the ischemic tree and stem are likely involved in the pathogenesis of PAOD, however the relative importance of each is …

Identifying And Reducing Variability, Improving Scaffold Morphology, And Investigating Alternative Materials For The Blood Vessel Mimic Lab Electrospinning Process, Evan M. Dowey

Master's Theses

The work of the Cal Poly Tissue Engineering Lab is primarily focused on the fabrication, characterization, and improvement of “Blood Vessel Mimics” (BVMs), tissue engineered constructs used to evaluate cellular response to vascular medical devices. Currently, cells are grown onto fibrous, porous tubes made using an in-house electrospinning process from PLGA, a biocompatible co-polymer. The adhesion and proliferation of cells in a BVM is reliant on the micro-scale structure of the PLGA scaffold, and as such it is of great importance for the electrospinning process to consistently produce scaffolds of similar morphologies. Additionally, it has been shown that cell proliferation …

Development And Characterization Of Tissue Engineered Blood Vessel Mimics Under "Diabetic" Conditions, Shelby Gabrielle Kunz

Master's Theses

The development of tissue engineered blood vessel mimics for the testing of intravascular devices in vitro has been established in the Cal Poly tissue engineering lab. Due to the prevalence of cardiovascular disease in diabetic patients and minimal accessible studies regarding the interactions between diabetes and intravascular devices used to treat vascular disease, there is a need for the development of diabetic models that more accurately represents diabetic processes occurring in the blood vessels, primarily endothelial dysfunction. This thesis aimed to create a diabetic blood vessel mimic by implementing a high glucose environment for culturing human endothelial cells from healthy …

Fluid Flow Characterization And In Silico Validation In A Rapid Prototyped Abdominal Aortic Aneurysm Model, Dean Thomas Wampler

Master's Theses

Aortic aneurysms are the 14^th leading cause of death in the United States. Annually, abdominal aortic aneurysm (AAA) ruptures are responsible for 4500 deaths. There are another 45,000 repair procedures performed to prevent rupture, and of these approximately 1400 lead to deaths. With proper detection, the aneurysm may be treated using endovascular aneurysm repair (EVAR). Understanding how the flow of the blood within the artery is affected by the aneurysm is important in determining the growth of the aneurysm, as well as how to properly treat the aneurysm. The goal of this project was to develop a physical construct …

Application Of Argon Plasma Technology To Hydrophobic And Hydrophilic Microdroplet Generation In Pdms Microfluidic Devices, Brennan P. Graham

Master's Theses

Abstract Application of Argon Plasma Technology to Hydrophobic and Hydrophilic Microdroplet Generation in PDMS Microfluidic Devices Brennan Graham Microfluidics has gained popularity over the last decade due to the ability to replace many large, expensive laboratory processes with small handheld chips with a higher throughput due to the small channel dimensions [1]. Droplet microfluidics is the field of fluid manipulation that takes advantage of two immiscible fluids to create droplets from the geometry of the microchannels. This project includes the design of a microfluidic device that applies the results of an argon plasma surface treatment to polydimethylsiloxane (PDMS) to successfully …

The Impacts Of Arterial Occlusion, Sex, And Exercise On Arteriogenesis And Functional Vasodilation, Megan Tze-Mei Chu

Master's Theses

The most frequent clinical presentation of peripheral arterial occlusive disease (PAOD) is intermittent claudication, which may be caused by impaired vasodilation. Patients demonstrate both local and systemic impairments in vasodilation, but as the collateral circulation is the primary site of resistance to the ischemic zone, impaired collateral vasodilation would have the greatest potential to induce claudication. Collateral function following arterial occlusion is not well defined, but immature collaterals may demonstrate impaired vasodilation in animal models, although this is potentially improved with exercise training. Furthermore, as females exhibit poorer physical function with ischemia and less improvement with therapeutic exercise, there appears …

Functional 3-D Cellulose And Nitrocellulose Paper-Based, Microfluidic Device Utilizing Elisa Technology For The Detection/Distinction Between Hemorrhagic And Ischemic Strokes, Alicia Leanne Holler

Master's Theses

The purpose of this thesis project is to demonstrate and evaluate an enzyme-linked immunosorbent assay (ELISA) on a paper microfluidic device platform. The integration of ELISA technology onto paper microfluidic chips allows for a quantitative detection of stroke biomarkers, such as glial fibrillary acidic protein (GFAP). Dye experiments were performed to confirm fluid connectivity throughout the 3D chips. Several chip and housing designs were fabricated to determine an optimal design for the microfluidic device. Once this design was finalized, development time testing was performed. The results confirmed that the paper microfluidic device could successfully route fluid throughout its channels at …

Quantifying Parkinson's Disease Symptoms Using Mobile Devices, Charles R. Aylward

Master's Theses

Current assessments for evaluating the progression of Parkinson’s Disease are largely qualitative and based on small sets of data obtained from occasional doctor-patient interactions. There is a clinical need to improve the techniques used for mitigating common Parkinson’s Disease symptoms. Available data sets for researching the disease are minimal, hindering advancement toward understanding the underlying causes and effectiveness of treatment and therapies. Mobile devices present an opportunity to continuously monitor Parkinson’s Disease patients and collect important information regarding the severity of symptoms. The evolution of digital technology has opened doors for clinical research to extend beyond the clinic by incorporating …

Nanoindentation Techniques For The Evaluation Of Silicon Nitride Thin Films, Weston T. Mangin

Master's Theses

Silicon nitride thin films are of interest in the biomedical engineering field due to their biocompatibility and favorable tribological properties. Evaluation and understanding of the properties of these films under diverse loading and failure conditions is a necessary prerequisite to their use in biomedical devices. Three wafers of silicon nitride-coated silicon were obtained from Lawrence Livermore National Laboratory and used to create 96 samples. Samples were subjected to nanoindentation testing to evaluate the mechanical properties of the film. Samples were subjected to nanoimpact testing to compare the damage resistance of the film to separate nanoimpact types. Samples were subjected to …

A 3-D Multiplex Paper-Microfluidic Platform, Mitchell Patrick Young

Master's Theses

3-D paper-based microfluidic devices (micoPADs) are small and portable devices made out of paper that offer a promising platform for diagnostic applications outside of a laboratory. These devices are easy to use, low cost, require no power source, and capable of detecting multiple targets simultaneously. The work in this thesis demonstrated the ability of a 3-D paper-microfluidic platform to simultaneously detect 5 targets. Rubber cord stock was used in conjunction with an acrylic housing unit to apply pressure along the edge of the channel. The indirect pressure application was successful in promoting vertical fluid flow between layers. Average channel development …

Fluid Flow Characterization And In Silico Validation In A Rapid Prototyped Aortic Arch Model, Alexandra Mariel Knauer

Master's Theses

Transcatheter aortic heart valve replacement (TAVR) is a procedure to replace a failing aortic valve and is becoming the new standard of care for patients that are not candidates for open-heart surgery [2]. However, this minimally invasive technique has shown to cause ischemic brain lesions, or “silent infarcts”, in 90% of TAVR patients, which can increase the patient’s risk for stroke by two to four times in future years [3]. Claret Medical Inc., a medical device company, has developed a cerebral protection system that filters and captures embolic debris released during endovascular procedures, such as TAVR. This thesis utilized CT …

Empirical Validation Of An In Silico Model Predicting The Fluid Dynamics Of An Iliac Artery Aneurysm, Rachel E. Willis

Master's Theses

Iliac artery aneurysms are considered rare and difficult to detect and treat. Prompt diagnosis and timely intervention are essential, because the incidence of rupture is as high as 50%. The reported mortality rate for patients who undergo surgery for ruptured iliac artery aneurysm ranges from 50% to 70%. This study developed an in-vitro mechanical model of an iliac artery aneurysm to verify the accuracy of computer simulation software. Both the in vitro model and the in silico model can be used for further research to develop better treatment technology. This study also looks at the different types of iliac artery …

The Effects Of Obesity On Resultant Knee Joint Loads For Gait And Cycling, Juan Gutierrez-Franco

Master's Theses

Osteoarthritis (OA) is a degenerative disease of cartilage and bone tissue and the most common form of arthritis, accounting for US$ 10.5 billion in hospital charges in 2006. Obesity (OB) has been linked to increased risk of developing knee OA due to increased knee joint loads and varus-valgus misalignment. Walking is recommended as a weight-loss activity but it may increase risk of knee OA as OB gait increases knee loads. Cycling has been proposed as an alternative weight-loss measure, however, lack of studies comparing normal weight (NW) and OB subjects in cycling and gait hinder identification of exercises that may …

Characterizing Neurotransmitter Receptor Activation With A Perturbation Based Decomposition Method, Stephen Gregory Jue

Master's Theses

The characterization of postsynaptic potentials, in terms of neurotransmitter receptor activation, is of clinical significance because information associated with receptor activation can be used in the diagnosis and study of neurological disorders. Single-unit recordings provide a method of measuring postsynaptic potentials in neurons using a microelectrode system, but yield no detailed information regarding the neurotransmitter receptors that contribute to the potential. To determine the types of neurotransmitter receptors that result in a compound postsynaptic potential from a microelectrode reading, decomposition of the potential is necessary. In this work, a perturbation-based decomposition method developed by R. Szlavik is evaluated for this …

Design And Validation Of A Fall Detection Application For Ios, Connor Lewis Mosley

Master's Theses

Despite significant preventative efforts, falls continue to be a major source of morbidity and mortality among the elderly. Additionally, the fear of falling can be a major obstacle to independent living for otherwise self-sufficient individuals. This fear is significantly heightened in individuals who have sustained a fall and often results in self-imposed restrictions on mobility and exercise, causing weakening in these individuals and further exacerbating the danger. Much time has been spent developing alert systems in an attempt to mitigate these problems. Unfortunately these systems typically involve dedicated monitoring centers and therefore often come with substantial upfront and recurring costs. …

Design And Analysis Of A Lift Assist Walker, Deep P. Shah

Master's Theses

Walkers provided stability to the elderly but cannot assist a person from sitting to standing. The objective of this project is to present the design and analysis of a lift assist walker. This report discusses the design and analysis of a collapsible lift assist walker capable of lifting a patient up to 250 lbs. from seated to standing in under 10 seconds. The designed walker utilized a two stage scissor mechanism with a gas spring assisted embedded linear actuator.

Fluid Flow Characterization In Rapid Prototyped Common Iliac Artery Aneurysm Molds, Daniel Cole Greinke

Master's Theses

The goal of this project was to determine whether i) fused deposition modeling could be employed to manufacture molds for vascular constructs, ii) whether vascular constructs could be created from these molds, and iii) to verify practical equivalence between observed fluid velocities. Dye tracking was to be employed to characterize fluid velocity profiles through the in vitro vascular constructs, including a half-vessel model and a full vessel model of an iliac artery aneurysm. A PDMS half-vessel construct was manufactured, and the movement of dye through the construct was tracked by a cellphone camera. Thresholds were applied to each video in …

The Effects Of Transcutaneous Electrical Neurostimulation On Analgesia And Peripheral Perfusion, Leah I. Schafer

Master's Theses

Peripheral arterial occlusive disease (PAOD) affects 8 to 12 million Americans over the age of 50. As the disease progresses, arterial occlusions arising from atherosclerotic lesions inhibit normal metabolic vasodilation in the peripheries, resulting in limb ischemia and claudication. Pharmacological and surgical treatments currently used to treat both the hemodynamic and pain symptoms associated with PAOD can involve adverse and potentially life-threatening side effects. Thus, there is a need for additional innovative therapies for PAOD.

Neurostimulation has a known analgesic effect on both acute and chronic pain. Although the exact mechanisms remain under investigation, local vascular tone may be modulated …

Identifying And Predicting Rat Behavior Using Neural Networks, Jonathan A. Gettner

Master's Theses

The hippocampus is known to play a critical role in episodic memory function. Understanding the relation between electrophysiological activity in a rat hippocampus and rat behavior may be helpful in studying pathological diseases that corrupt electrical signaling in the hippocampus, such as Parkinson’s and Alzheimer’s. Additionally, having a method to interpret rat behaviors from neural activity may help in understanding the dynamics of rat neural activity that are associated with certain identified behaviors.

In this thesis, neural networks are used as a black-box model to map electrophysiological data, representative of an ensemble of neurons in the hippocampus, to a T-maze, …

Modeling Viscoelastic Behavior In Compact Bone Through A Distribution Of Collagen D-Spacing: A Finite Element Analysis, Christopher Ha

Master's Theses

Osteoporosis affects nearly 54 million people in the United States. The cost associated with treatment is estimated to be $19 billion per year and is expected to grow yearly. D-spacing is the staggering of collagen molecules found at the nanoscopic level. Previously thought to have a constant value, recent studies have found that D-spacing has a distribution of values throughout the tissue. As part of an ongoing effort in understanding the mechanisms that are affected by osteoporosis, a finite element model was developed to explore the effects of D-spacing distribution on the viscoelastic material properties of bone tissue. The goal …