Theses and Dissertations
This collection includes both ASU Theses and Dissertations, submitted by graduate students, and the Barrett, Honors College theses submitted by undergraduate students.
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- Creators: Harrington Bioengineering Program
Description
The intervertebral disc goes through degenerative changes with age, which leads to disc thinning, bulging, or herniation. Spinal fusion treatments are ineffective as they cause quicker degeneration of adjacent discs and fail in nearly 20% of cases, so researchers have turned to tissue-engineering biocompatible intervertebral discs for transplantation. However novel and effective as this may seem, these transplanted discs still show evidence of degeneration after just 5 years. I hypothesize that these discs are degenerating due to a blockage of the cartilaginous endplates post-transplantation that is hindering nutrient transport through the intervertebral disc. In order to test this hypothesis, I developed a mathematical model of nutrient transport through the intervertebral disc in one diurnal daily loading cycle. This model was used to simulate open endplates and blocked endplates and then compare differences in nutrient concentration and nutrient transport to the center of the disc. Results from the math model simulations were then compared to in vitro experimental data collected in lab to verify the findings on a physiological level. Results showed significant differences, both in vitro and in the model, between nutrient transport in open endplates vs blocked endplates, lending support to the original hypothesis. This study only presents preliminary results, but could hold the key to preventing future disc degeneration post-transplantation.
ContributorsMunter, Bryce Taylor (Author) / Santello, Marco (Thesis director) / Caplan, Michael (Committee member) / Giers, Morgan (Committee member) / Barrett, The Honors College (Contributor) / Harrington Bioengineering Program (Contributor)
Created2015-05
Description
Growing concern over health risks associated with environmental contaminants has prompted an increase in the search for effective detection methods. The available options provide acceptable sensitivity and specificity, but with high purchase and maintenance costs. Herein, a low-cost, portable environmental contaminant sensor was developed using electrochemical techniques and an efficient hydrogel capture mechanism. The sensor operates with high sensitivity and maintains specificity without the added requirement of extensive electrode modification. Rather, specificity is obtained by choosing specific potential regions in which individual contaminants show reduction or oxidation activity. A calibration curve was generated showing the utility of the sensor in detecting gas compounds reliably in reference to a current state of the art sensor. Reusability of the sensor was also demonstrated with a cyclic exposure test in which response reversibility was observed. As such, the investigated sensor shows great promise as a replacement technology in the current environmental contaminant detector industry.
ContributorsMarch, Michael Stephen (Author) / LaBelle, Jeffrey (Thesis director) / Caplan, Michael (Committee member) / Barrett, The Honors College (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Harrington Bioengineering Program (Contributor)
Created2014-05
Description
Improving medical aerosols is the multifaceted objective that is the overarching theme of this work. This thesis is the culmination of many hours of academic research. It details the current mechanical and physiological obstacles of state of the art drug inhalation technology, as well as provides a detailed guide of the experimental set up, procedure, analysis and background for the charge neutralization experiments performed by the author. The findings of this research are that inhalation devices need to become personalized; meaning adjustable flow rates, particle sizes, and charge levels. To improve the efficiency of lung deposition they could use MRI to take advantage of 3D modeling software to make transport models of an individual patient's lungs. This model would allow an engineer to calculate the air velocity in each passage of the respiratory system and would account for any pulmonary obstructions that would completely alter the deposition pattern from the average healthy patient. With the velocity profile of the lung a doctor could formulate an aerosol with the perfect attributed for the most targeted delivery. For the experiments performed in this work the following results were obtained. The ionization of air by polonium 210 alpha particles is dependent on the distance from the alpha emitting source and the strength of the electric field. Furthermore discharge of aerosol droplets is possible through volume conduction however the mass of the polonium 210 isotope must be proportional to the ionization current demand.
ContributorsKotin, Matthew Aaron (Author) / Towe, Bruce (Thesis director) / Caplan, Michael (Committee member) / Barrett, The Honors College (Contributor) / Harrington Bioengineering Program (Contributor)
Created2014-05
Description
Intracranial aneurysms are blood \u2014filled sacs along the blood vessels in the brain. These aneurysms can be particularly dangerous due to difficulty in detection and potential lifethreatening outcome. When these aneurysms are detected, there are few treatment options to prevent rupture, one of which is endovascular stents. By placing a stent across the parent vessel, blood flow can be diverted from the aneurysm. Reduced flow reduces the chance of rupture and promotes clotting within the aneurysm. In this study, hemodynamics in idealized basilar tip aneurysm models were investigated at three flow rates using particle imaging velocimetry (PIV). Two models were created with increasing dome size (4mm vs 6mm), and constant dome-to-neck ratio (3:2) and parent vessel contact angle to represent growing aneurysm. With the pulsatile flow, data is acquired at three separate points in the cardiac cycle. Both of the models were studied untreated, treated with Enterprise stent and treated with Pipeline stent. Enterprise stent was developed mainly for structural support while the Pipeline stent was developed as a flow diverter. Due to target functions of the stents, Enterprise stent is more porous than the Pipeline stent. Hemodynamics were studied using a stereo particle image velocimetry technique. The flow in models was characterized by neck and aneurysmal RMS velocity, neck and aneurysm kinetic energy, cross neck flow. It was found that both of the stents are capable diverting flow. Enterprise reduced aneurysmal RMS velocity in model 1 by 38.7% and in model 2 by 76.2%. Pipeline stent reduced aneurysmal RMS velocity in model 1 by 71.4% and in model 2 by 88.1%. Both reductions are data for 3ml/s at peak systole pulsatile flow. Data shows that the Pipeline stent is better than Enterprise stent at reducing flow to the aneurysm.
ContributorsChung, Hanseung (Author) / Frakes, David (Thesis director) / Caplan, Michael (Committee member) / Babiker, Haithem (Committee member) / Barrett, The Honors College (Contributor) / Economics Program in CLAS (Contributor) / Harrington Bioengineering Program (Contributor)
Created2014-05
Description
The use of saliva sampling as a noninvasive way for drug analysis as well as the monitoring systems within the body has become increasingly important in recent research. Because of the growing interest in saliva, this project proposes a way to analyze sodium ion concentration in a saliva solution based on its fluorescence level when in the presence of a sodium indicator dye and recorded with a smartphone camera. The dyed sample was placed in a specially designed housing to exclude all ambient light from the images. A source light of known wavelength was used to excite the fluorescent dye and the smartphone camera images recorded the emission light wavelengths. After analysis of the images using ImageJ, it was possible to create a model to determine the level of fluorescence based on sodium ion concentration. The smartphone camera image model was compared to readings from a standard fluorescence plate recorder to test the accuracy of the model. The study found that the model was accurate within 5 % as compared to the fluorescence plate recorder. Based on the results, it was concluded that the method and resulting model proposed in this study is a valid was to analyze saliva or other solutions for their sodium ion concentration via images recorded by a smartphone camera.
ContributorsSmith, Catherine Julia (Author) / Antonio, Garcia (Thesis director) / Caplan, Michael (Committee member) / Barrett, The Honors College (Contributor) / Harrington Bioengineering Program (Contributor)
Created2014-05
Description
Flipped classrooms invert the traditional teaching methods and deliver the lecture online outside of the classroom. An increase in technology accessibility is increasing the prevalence of this teaching technique in universities. In this study, we aim to address some of the uncertainties of a flipped classroom by implementing a new lecture format in Transport Phenomena. Transport Phenomena is a junior level biomedical engineering course originally flipped in Spring 2013. Since transitioning to a flipped classroom, students have been required to watch 75-minute lectures outside of class where the instructor covered key concepts and examples using paper and marker on a document camera. In class, students then worked in groups to solve problems with instructor and teaching assistant feedback. Students also completed self-graded homework with the opportunity to earn lost points back by discussing fundamental misconceptions. We are introducing re-formatted mini lectures that contain the same content broken down as well as example problems worked out in a tutorial technique instead of traditional solving method. The purpose of this study is to determine the effectiveness of newly created mini lectures with integrated questions and links in terms of student achievement and attitude [interest, utility, and "cost" (time, effort, and emotion)].
ContributorsBrenna, Samantha Paige (Author) / Ankeny, Casey (Thesis director) / Caplan, Michael (Committee member) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
Traumatic brain injury (TBI) is a leading cause of injury related death in the United States. The complexity of the injury environment that follows TBI creates an incomplete understanding of all the mechanisms in place to regulate chemotactic responses to TBI. The goal of this project was to develop a predictive in silco model using diffusion and autocrine/paracrine signaling specific to stromal cell derived factor-1α (SDF-1α) gradient formation after TBI and compare this model with in vivo experimental data. A COMSOL model using Fickian diffusion and autocrine/paracrine reaction terms was generated to predict the gradient formation observed in vivo at three physiologically relevant time points (1, 3, and 7 days). In vivo data was gathered and analyzed via immunohistochemistry and MATLAB. The spatial distribution of SDF-1α concentration in vivo more consistently demonstrated patterns similar to the in silico model dependent on both diffusion and autocrine/paracrine reaction terms rather than diffusion alone. The temporal distribution of these same results demonstrated degradation of SDF-1α at too rapid a rate, compared to the in vivo results. To account for differences in behavior observed in vivo, reaction terms and constants of 1st-order reaction rates must be modulated to better reflect the results observed in vivo. These results from both the in silico model and in vivo data support the hypothesis that SDF-1α gradient formation after TBI depends on more than diffusion alone. Future work will focus on improving the model with constants that are specific to SDF-1α as well as testing methods to better control the degradation of SDF-1α.
ContributorsFreeman, Sabrina Louise (Author) / Stabenfeldt, Sarah (Thesis director) / Caplan, Michael (Committee member) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05