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- All Subjects: engineering
- Creators: Harrington Bioengineering Program
- Creators: Goryll, Michael
Description
The partially-depleted (PD) silicon Metal Semiconductor Field Effect Transistor (MESFET) is becoming more and more attractive for analog and RF applications due to its high breakdown voltage. Compared to conventional CMOS high voltage transistors, the silicon MESFET can be fabricated in commercial standard Silicon-on-Insulator (SOI) CMOS foundries without any change to the process. The transition frequency of the device is demonstrated to be 45GHz, which makes the MESFET suitable for applications in high power RF power amplifier designs. Also, high breakdown voltage and low turn-on resistance make it the ideal choice for switches in the switching regulator designs. One of the anticipated applications of the MESFET is for the pass device for a low dropout linear regulator. Conventional NMOS and PMOS linear regulators suffer from high dropout voltage, low bandwidth and poor stability issues. In contrast, the N-MESFET pass transistor can provide an ultra-low dropout voltage and high bandwidth without the need for an external compensation capacitor to ensure stability. In this thesis, the design theory and problems of the conventional linear regulators are discussed. N-MESFET low dropout regulators are evaluated and characterized. The error amplifier used a folded cascode architecture with gain boosting. The source follower topology is utilized as the buffer to sink the gate leakage current from the MESFET. A shunt-feedback transistor is added to reduce the output impedance and provide the current adaptively. Measurement results show that the dropout voltage is less than 150 mV for a 1A load current at 1.8V output. Radiation measurements were done for discrete MESFET and fully integrated LDO regulators, which demonstrate their radiation tolerance ability for aerospace applications.
ContributorsChen, Bo (Author) / Thornton, Trevor (Thesis advisor) / Bakkaloglu, Bertan (Committee member) / Goryll, Michael (Committee member) / Arizona State University (Publisher)
Created2013
Description
Pelvic Circumferential Compression Devices (PCCDs), an important medical device when caring for patients with pelvic fractures, play a crucial role in the stabilization and reduction of the fracture. During pelvic fracture cases, control of internal bleeding through access to the femoral artery is of utmost importance. Current designs of PCCDs do not allow vital access to this artery and in attempts to gain access, medical professionals and emergency care providers choose to cut into the PCCDs or place them in suboptimal positions with unknown downstream effects. We researched the effects on surface pressure and the overall pressure distribution created by the PCCDs when they are modified or placed incorrectly on the patient. In addition, we investigated the effects of those misuses on pelvic fracture reduction, a key parameter in stabilizing the patient during critical care. We hypothesized that incorrectly placing or modifying the PCCD will result in increased surface pressure and decreased fracture reduction. Our mannequin studies show that for SAM Sling and T-POD, surface pressure increases if a PCCD is incorrectly placed or modified, in support of our hypothesis. However, opposite results occurred for the Pelvic Binder, where the correctly placed PCCD had higher surface pressure when compared to the incorrectly placed or modified PCCD. Additionally, pressure distribution was significantly affected by the modification of the PCCDs. The cadaver lab measurements show that modifying or incorrectly placing the PCCDs significantly limits their ability to reduce the pelvic fracture. These results suggest that while modifying or incorrectly placing PCCDs allows access to the femoral artery, there are potentially dangerous effects to the patient including increased surface pressures and limited fracture reduction.
ContributorsConley, Ian Patrick (Co-author) / Ryder, Madison (Co-author) / Vernon, Brent (Thesis director) / Bogert, James (Committee member) / Harrington Bioengineering Program (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description
To supplement lectures, various resources are available to students; however, little research has been done to look systematically at which resources studies find most useful and the frequency at which they are used. We have conducted a preliminary study looking at various resources available in an introductory material science course over four semesters using a custom survey called the Student Resource Value Survey (SRVS). More specifically, the SRVS was administered before each test to determine which resources students use to do well on exams. Additionally, over the course of the semester, which resources students used changed. For instance, study resources for exams including the use of homework problems decreased from 81% to 50%, the utilization of teaching assistant for exam studying increased from 25% to 80%, the use of in class Muddiest Points for exam study increased form 28% to 70%, old exams and quizzes only slightly increased for exam study ranging from 78% to 87%, and the use of drop-in tutoring services provided to students at no charge decreased from 25% to 17%. The data suggest that students thought highly of peer interactions by using those resources more than tutoring centers. To date, no research has been completed looking at courses at the department level or a different discipline. To this end, we adapted the SRVS administered in material science to investigate resource use in thirteen biomedical engineering (BME) courses. Here, we assess the following research question: "From a variety of resources, which do biomedical engineering students feel addresses difficult concept areas, prepares them for examinations, and helps in computer-aided design (CAD) and programming the most and with what frequency?" The resources considered include teaching assistants, classroom notes, prior exams, homework problems, Muddiest Points, office hours, tutoring centers, group study, and the course textbook. Results varied across the four topical areas: exam study, difficult concept areas, CAD software, and math-based programming. When preparing for exams and struggling with a learning concept, the most used and useful resources were: 1) homework problems, 2) class notes and 3) group studying. When working on math-based programming (Matlab and Mathcad) as well as computer-aided design, the most used and useful resources were: 1) group studying, 2) engineering tutoring center, and 3) undergraduate teaching assistants. Concerning learning concepts and exams in the BME department, homework problems and class notes were considered some of the highest-ranking resources for both frequency and usefulness. When comparing to the pilot study in MSE, both BME and MSE students tend to highly favor peer mentors and old exams as a means of studying for exams at the end of the semester1. Because the MSE course only considered exams, we cannot make any comparisons to BME data concerning programming and CAD. This analysis has highlighted potential resources that are universally beneficial, such as the use of peer work, i.e. group studying, engineering tutoring center, and teaching assistants; however, we see differences by both discipline and topical area thereby highlighting the need to determine important resources on a class-by-class basis as well.
ContributorsMalkoc, Aldin (Author) / Ankeny, Casey (Thesis director) / Krause, Stephen (Committee member) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
The action/adventure game Grad School: HGH is the final, extended version of a BME Prototyping class project in which the goal was to produce a zombie-themed game that teaches biomedical engineering concepts. The gameplay provides fast paced, exciting, and mildly addicting rooms that the player must battle and survive through, followed by an engineering puzzle that must be solved in order to advance to the next room. The objective of this project was to introduce the core concepts of BME to prospective students, rather than attempt to teach an entire BME curriculum. Based on user testing at various phases in the project, we concluded that the gameplay was engaging enough to keep most users' interest through the educational puzzles, and the potential for expanding this project to reach an even greater audience is vast.
ContributorsNitescu, George (Co-author) / Medawar, Alexandre (Co-author) / Spano, Mark (Thesis director) / LaBelle, Jeffrey (Committee member) / Guiang, Kristoffer (Committee member) / Barrett, The Honors College (Contributor) / Harrington Bioengineering Program (Contributor)
Created2014-05
Description
Volume depletion can lead to migraines, dizziness, and significant decreases in a subject's ability to physically perform. A major cause of volume depletion is dehydration, or loss in fluids due to an imbalance in fluid intake to fluid excretion. Because proper levels of hydration are necessary in order to maintain both short and long term health, the ability to monitor hydration levels is growing in clinical demand. Although devices capable of monitoring hydration level exist, these devices are expensive, invasive, or inaccurate and do not offer a continuous mode of measurement. The ideal hydration monitor for consumer use needs to be characterized by its portability, affordability, and accuracy. Also, this device would need to be noninvasive and offer continuous hydration monitoring in order to accurately assess fluctuations in hydration data throughout a specified time period. One particular method for hydration monitoring that fits the majority of these criteria is known as bioelectric impedance analysis (BIA). Although current devices using BIA do not provide acceptable levels of accuracy, portability, or continuity in data collection, BIA could potentially be modified to fit many, if not all, desired customer specifications. The analysis presented here assesses the viability of using BIA as a new standard in hydration level measurement. The analysis uses data collected from 22 subjects using an existing device that employs BIA. A regression derived for estimating TBW based on the parameters of age, weight, height, sex, and impedance is presented. Using impedance data collected for each subject, a regression was also derived for estimating impedance based on the factors of age, weight, height, and sex. The derived regression was then used to calculate a new impedance value for each subject, and these new impedance values were used to estimate TBW. Through a paired-t test between the TBW values derived by using the direct measurements versus the calculated measurements of impedance, the two samples were found to be comparable. Considerations for BIA as a noninvasive measurement of hydration are discussed.
ContributorsTenorio, Jorge Antonio (Author) / LaBelle, Jeffrey (Thesis director) / Pizziconi, Vincent (Committee member) / Spano, Mark (Committee member) / Barrett, The Honors College (Contributor) / W. P. Carey School of Business (Contributor) / Harrington Bioengineering Program (Contributor)
Created2013-05
Description
The constant scaling of supply voltages in state-of-the-art CMOS processes has led to severe limitations for many analog circuit applications. Some CMOS processes have addressed this issue by adding high voltage MOSFETs to their process. Although it can be a completely viable solution, it usually requires a changing of the process flow or adding additional steps, which in turn, leads to an increase in fabrication costs. Si-MESFETs (silicon-metal-semiconductor-field-effect-transistors) from Arizona State University (ASU) on the other hand, have an inherent high voltage capability and can be added to any silicon-on-insulator (SOI) or silicon-on-sapphire (SOS) CMOS process free of cost. This has been proved at five different commercial foundries on technologies ranging from 0.5 to 0.15 μm. Another critical issue facing CMOS processes on insulated substrates is the scaling of the thin silicon channel. Consequently, the future direction of SOI/SOS CMOS transistors may trend away from partially depleted (PD) transistors and towards fully depleted (FD) devices. FD-CMOS are already being implemented in multiple applications due to their very low power capability. Since the FD-CMOS market only figures to grow, it is appropriate that MESFETs also be developed for these processes. The beginning of this thesis will focus on the device aspects of both PD and FD-MESFETs including their layout structure, DC and RF characteristics, and breakdown voltage. The second half will then shift the focus towards implementing both types of MESFETs in an analog circuit application. Aside from their high breakdown ability, MESFETs also feature depletion mode operation, easy to adjust but well controlled threshold voltages, and fT's up to 45 GHz. Those unique characteristics can allow certain designs that were previously difficult to implement or prohibitively expensive using conventional technologies to now be achieved. One such application which benefits is low dropout regulators (LDO). By utilizing an n-channel MESFET as the pass transistor, a LDO featuring very low dropout voltage, fast transient response, and stable operation can be achieved without an external capacitance. With the focus of this thesis being MESFET based LDOs, the device discussion will be mostly tailored towards optimally designing MESFETs for this particular application.
ContributorsLepkowski, William (Author) / Thornton, Trevor (Thesis advisor) / Bakkaloglu, Bertan (Committee member) / Goryll, Michael (Committee member) / Ayyanar, Raja (Committee member) / Arizona State University (Publisher)
Created2010
Description
Pelvic Circumferential Compression Devices (PCCDs), an important medical device when caring for patients with pelvic fractures, play a crucial role in the stabilization and reduction of the fracture. During pelvic fracture cases, control of internal bleeding through access to the femoral artery is of utmost importance. Current designs of PCCDs do not allow vital access to this artery and in attempts to gain access, medical professionals and emergency care providers choose to cut into the PCCDs or place them in suboptimal positions with unknown downstream effects. We researched the effects on surface pressure and the overall pressure distribution created by the PCCDs when they are modified or placed incorrectly on the patient. In addition, we investigated the effects of those misuses on pelvic fracture reduction, a key parameter in stabilizing the patient during critical care. We hypothesized that incorrectly placing or modifying the PCCD will result in increased surface pressure and decreased fracture reduction. Our mannequin studies show that for SAM Sling and T-POD, surface pressure increases if a PCCD is incorrectly placed or modified, in support of our hypothesis. However, opposite results occurred for the Pelvic Binder, where the correctly placed PCCD had higher surface pressure when compared to the incorrectly placed or modified PCCD. Additionally, pressure distribution was significantly affected by the modification of the PCCDs. The cadaver lab measurements show that modifying or incorrectly placing the PCCDs significantly limits their ability to reduce the pelvic fracture. These results suggest that while modifying or incorrectly placing PCCDs allows access to the femoral artery, there are potentially dangerous effects to the patient including increased surface pressures and limited fracture reduction.
ContributorsRyder, Madison Taylor (Co-author) / Conley, Ian (Co-author) / Vernon, Brent (Thesis director) / Bogert, James (Committee member) / School of Mathematical and Statistical Sciences (Contributor) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description
The Honors Creative Project evolved drastically from start to finish, despite its origin remaining the same. My core goal in this project was to connect two seemingly mutually exclusive aspects of my life, engineering and dance. After conducting an IRB study and using data from my own personal experiences, I was able to see how dance had in fact made me a better engineer. There were skills that I gained and learned in dance that were directly applicable to engineering, and I believe will be critical to my success as an engineer. As the focal point of the project angled towards myself, I had to look deeply into who I am and how I reached this point. I conducted self-reflections on various aspects of my current life and also on the struggles and hardships I overcame during my years at ASU. From these reflections, I learned a lot about myself and how my personal identity has evolved. This identity evolution became the backbone behind my thesis defense. I took my research and self-reflections and designed a series of artwork that I personally designed and painted myself. I my engineering side to conduct the research and collect the data, and then used my artistic side to present my findings to the public in a way that attracted and audience and caused others to reflect upon their own identities.
ContributorsArizmendi, Romann Fuentes (Author) / Olarte, David (Thesis director) / Welz, Matt (Committee member) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Piloerection (known as goosebumps) is mediated by activation of alpha-adrenergic receptors within the sympathetic branch of the autonomic nervous system. The study of piloerection is important in multiple fields, from emotion studies to nervous system pathology. This makes piloerection particularly relevant to emotions research. Despite wide-ranging applications, current methods for measuring piloerection are laborious and qualitative. The goal of this study is to build a wearable piloerection sensor through the use of straight-line lasers and photoresistors. The study analyzed methods of detecting and measuring goosebumps, and applied the method of laser scattering as a detection method. This device was designed and tested against a population of seven Arizona State University students. Goosebumps were elicited through conditions of cold, and video clips meant to elicit emotions of awe and sadness. Piloerection was then quantified through two controls of self-identification and camera recording, as well as the new detection method. These were then compared together, and it was found that subjective methods of determining goosebumps did not correlate well with objective measurements, but that the two objective measurements correlated well with one another. This shows that the technique of laser scattering can be used to detect goosebumps and further developments on this new detection method will be made. Moreover, the presence of uncorrelated subjective measurements further shows the need for an objective measurement of piloerection, while also bringing into question other factors that may be confused with the feeling of piloerection, such as chills or shivers. This study further reaffirmed previous studies showing a positive correlation between intense emotions.
ContributorsHemesath, Angela (Author) / Muthuswamy, Jitendran (Thesis director) / Shiota, Michelle (Lani) (Committee member) / Harrington Bioengineering Program (Contributor, Contributor) / School of Molecular Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Curtiss-Wright Corporation is a global company that manufactures and provides services for the commercial, industrial, defense, and energy departments. The Curtiss-Wright facility that was the focus of this research is part of the Sensors and Controls Division and focuses on manufacturing and assembling aircraft components. Visual Factory, an electronic work instructions software, was implemented for a trial run for two products on the assembly floor. Data collected from several workstations and operators was analyzed to determine if there were impacts to product quality or changes in assembly completion times when using Visual Factory. After analyzing data from six operators and six workstations, it was found that operators could complete processes in less time than was previously believed. Timing data also helped to create standardized learning curves and improvement percentages for specific workstations and processes. This data allows management and supervisors to more adequately allocate time for training and extrapolate post-training completion times based on initial completion times. Part quality data was less abundant, but there were fewer major issues with part quality when using Visual Factory. Visual Factory also allowed for more in-depth collection of quality issues on specific units. It is recommended that Curtiss-Wright continues with implementation of Visual Factory across the entire assembly floor and all product lines.
ContributorsNelson, Jade Hunter (Author) / Coursen, Jerry (Thesis director) / Rossiter, John (Committee member) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05