Engineering Commons^™

Microwave Imaging Technique For Breast Cancer Detection, Nure Alam Chowdhury

Theses and Dissertations

Breast cancer is a global problem, and it is inevitable to detect cancerous cells at early stages. In recent years, microwave imaging technology has been widely applied in biomedical applications for its non-ionizing radiation. In this study, we design a micro-strip patch antenna with an inverted T-type notch in the partial ground to detect tumor cells inside the human breast. The size of the current antenna is small enough (18 mm × 21 mm × 1.6 mm) to distribute around the breast phantom. The operating frequency has been observed from 6–14 GHz with a minimum return loss of −61.18 dB …

Deep Learning And Generative Ai Approaches For Automated Diagnosis And Personalized Treatment: Bridging Machine Learning, Medicine, And Biomechanics In Predicting Tissue Mechanics And Biomaterial Properties., Yasin Shokrollahi

Theses and Dissertations

Machine learning, particularly deep neural networks, has demonstrated significant potential in predicting high-dimensional tasks across various domains. This work encompasses a detailed review of Generative AI in healthcare and three studies integrating machine learning with finite element analysis for predicting biomechanical behaviors and properties. Initially, we provide a comprehensive overview of Generative AI applications in healthcare, focusing on Transformers and Denoising Diffusion models and suggesting potential research avenues to address existing challenges.

Subsequently, we addressed soccer-related ocular injuries by combining finite element analysis and machine learning to predict retinal mechanics following a soccer ball hit rapidly. The prediction errors are …

Development Of A Pediatric Heart Assist Device Monitoring System, Natalie Hill

Theses and Dissertations

Heart failure (HF) is one of the leading causes of deaths for adults worldwide, but has disproportionately significant effects on pediatric patients that are often overshadowed. Treatment options for pediatric patients with HF are extremely limited, resulting in increased mortality rates within hospitals. Patients often depend on ventricular assist device (VAD) support as a bridge to transplant. The Berlin Heart EXCOR is the only FDA approved device for pediatric use in the US. However, many hemodynamic and neurological complications continue to arise; for instance, up to 30% of EXCOR patients suffer from stroke. Currently, there is no effective way to …

Characterizing Endothelial Damage During Ischemic Stroke Treatment With 3d Cerebrovascular Live Cellular And Finite Element Models, Ana Regina Martinez Dehesa

Theses and Dissertations

Stent retriever mechanical thrombectomy (SRMT) is part of the clinical standard-of-care for acute ischemic stroke (AIS) patients with large vessel occlusion (LVO). Endothelial injury (EI) is widely associated with SRMT. Studies report finding EI markers in over 50% of retrieved clots, suggesting the frequency of EI in MT patients is rather common. The mechanism of EI and its contribution to MT failure and clinical outcomes remain poorly understood because of a lack of techniques to observe EI and study it in vitro. This study aims to investigate the mechanisms of EI induced by SRMT, as well as the effect stent …

Xeno-Free Biomimetic Ecm Model For Investigation Of Matrix Properties On Astrocyte Cell Response, Bayan Saleh

Theses and Dissertations

Astrocytes are crucial in preserving the structural and functional integrity of the central nervous system (CNS). They participate in several physiological processes, such as the uptake of neurotransmitters, control of extracellular ion concentration, and preservation of the blood-brain barrier. Recent research has raised the possibility that astrocytes are also involved in the onset and development of Alzheimer's disease (AD). While the precise mechanisms underlying the development and progression of AD are not fully understood, recent research has suggested that age-related changes in the brain extracellular matrix (ECM) properties may play a critical role in the progression of the disease. Investigating …

Development Of A Customizable Framework For Data Driven Hemodynamic Analysis With Applications In Neurovascular And Cardiovascular Scenarios, Rachel Mae Hillner

Theses and Dissertations

Cardiovascular disease, including but not limited to heart failure and aneurysms, remain a leading cause of death worldwide. Persons over the age of 40 experience upwards of a 20% chance of developing heart failure in their lifetime. With a decrease in viable donor hearts, the reliance on mechanical heart assist devices is on the rise. However, such devices are not without their complications. Specifically, for left heart failure, a common treat, the left ventricular assist device, is characterized by clotting, stroke, and low survival rates as a result. Many studies suggest that such unfavorable results are correlated to adverse hemodynamic …

A Reduced Order Model For Estimation Of Fractional Flow Reserve (Ffr) In Coronary Artery Disease: Assessing The Impact Of Side Branches, Arber Vila

Theses and Dissertations

Coronary Artery Disease (CAD) affects millions of people worldwide and remains a leading cause of morbidity and mortality. To effectively plan treatment and risk stratification, assessing CAD severity is of paramount importance. Fractional flow reserve (FFR) is a critical clinical parameter used to evaluate CAD severity, measured by the ratio of mean distal coronary pressure to mean aortic pressure during hyperemic conditions. Although non-invasive FFR estimation methods have gained popularity, computational fluid dynamics (CFD) is impractical for routine clinical use due to the time and resources required. To address this issue, a reduced order model is proposed that accurately captures …

Importance Of Light Activation For Plant Cryptochrome And Antibacterial Drug Delivery Strategies, Merfat Ahmed Hammad

Theses and Dissertations

The goal of this project is to investigate the benefits of applying light in different systems. In the first part, the magnetoreception process that occurs in the light activated cryptochrome of Arabidopsis Thaliana was investigated. In the second part, photo-carbon monoxide releasing molecules (photo-CORMs) were investigated for their antibacterial effect to develop biomedical strategies. Overall, this has been achieved in three different studies. The first study investigated if the forward lightdriven reaction is involved in the magnetoreception process or not in cryptochrome (CRY). To accomplish this, the plant seedlings were tested for 90 minutes as follows: 5 minutes in the …

Investigating The Role Of Cryptochrome Activity In Arabidopsis Plant And Blue Light Exposure In Saos-2 Cell-Mediated Mineralization, Maria Nijr Albaqami

Theses and Dissertations

Cryptochromes (CRYs) are flavoproteins that absorb blue light and are associated with the perception of electromagnetic stimuli in a variety of organisms including animals and plants. When exposed to blue light, CRYs undergo flavin redox cycles and form radical pairs intermediates that are assumed to be magnetically sensitive as predicted by the radical-pair hypothesis. However, it is unknown if CRYs fulfill the criteria to act as biological magnetosensors. In the first aim, Arabidopsis thaliana seedlings were exposed to blue light and a time-dependent weak magnetic field at radiofrequency (RF) of 7 MHz as a diagnostic tool to test the radical-pair …

Optimizing Left Ventricular Assist Device Hemodynamics Via Patient Specific Computational Analysis, Jasmine Josefina Martinez

Theses and Dissertations

The best treatment for patients with end stage heart failure is a heart transplant but given the scarcity of donor hearts, a promising alternative treatment has become left ventricular assist devices (LVAD). However, complications such as right heart failure, stroke, and adverse hemodynamic outcomes continue to occur. This thesis will cover investigations into continuous flow LVAD treatment optimization techniques to improve patient outcomes. Optimization techniques explored include an in-house developed optimization algorithm that is completed in three phases on a computational lumped parameter model that is representative of the cardiovascular system using an electrical circuit analogy. This three-phase optimization technique …

Computer Vision And Machine Learning Applications In Cellular Images And Clinical Data, Guochang Ye

Theses and Dissertations

With the progressive development of artificial intelligence (AI), automated analysis has been explored for substituting tedious manual methods in cellular image analysis. Additionally, medical information not included in the conventional statistical methods is now being reconsidered with AI-based personalized medicine. The adaptivity and flexibility of AI ensure its efficiency and accuracy. In this work, computer vision and machine learning (ML) methods under the scope of AI are explicitly investigated and applied to cellular images and clinical data for cytological analysis and to provide diagnosis-based assistance/predictions. Firstly, novel computer vision algorithms achieve cell detection and differentiation estimation on phase-contact microscopic images …

Cellular Migration As A Function Of Magnetic Field Intervention, Amy Marie Vecheck

Theses and Dissertations

This work aims to assess cellular migration in three-dimensional structures as a function of Zeeman resonance. By using Zeeman resonance to initialize intersystem crossing of electrons, also known as the Radical Pair Mechanism, bioenergetics processes would be modulated. Processes such as oxygen consumption rate and extracellular acidification rate are indicative of cellular respiration and glycolysis and can be altered based on the orientation of the magnetic field applied: parallel and perpendicular, respectively. This study focused on the parallel orientation and looked to used Zeeman resonance to increase flavin adenosine dinucleotide, which results in preventing the breakdown of F-actin. Cellular viability …

Effects Of Orthopedic Implant And Host Bone Properties On Stress-Shielding Induced Osteopenia, Scott Jason Jan Baskerville

Theses and Dissertations

Stress shielding is a term commonly used in literature to describe a bone density reducing phenomenon which occurs due to long-term exposure of bone tissue to sub-homeostatic levels of mechanical stimuli. A number of mechanobiological models ranging in complexity and purpose have been developed with the general overall intent of predicting bone remodeling behavior under a set of prescribed conditions. A previously developed heuristic model is expanded in the present work through model calibration with physiological data and the development of a reduced bone-implant-construct (BIC) mechanical model configurable for patient factors such as age, gender, and associated bone properties. The …

Influence Of Mouthguard Design On Sports Performance And Injury Prevention, Mohammad Ahmed

Theses and Dissertations

Contact sports are associated with some invisible injuries after the incident when symptoms do not appear until weeks after. This can be dangerous as players may continue to engage in the sport and risk further injury. Athletic mouthguards are used to reduce the risk of injury, but there is insufficient data to quantify the effectiveness of mouthguard design on sports performance and injury prevention. In this work, the thickness and material selection of the mouthguard design were characterized in terms of airway resistance, electromyography muscle activation, and energy absorption. First, the effect of thickness on the condyle and temporal bone …

Endothelial Response In 2d And 3d To Doses Of Photosensitive Carbon Monoxide Releasing Molecules With Improved Activation, Nicholas Duc Huynh

Theses and Dissertations

Cardiovascular disease (CVD) is the leading cause of death worldwide in large part due to atherosclerotic obstruction of blood vessels. Limitations with current treatment approaches include restenosis in stenting and viable donor-tissue for bypass grafts, and this has motivated research combining the fields of drug delivery and tissue engineering for alternative approaches. The use of carbon monoxide as a potential therapeutic agent in the treatment of CVD has shown potential impacts on vasodilation and anti-inflammation. The goal of this study was to develop a system to elucidate the response of endothelial cells post-exposure to different concentrations of carbon monoxide releasing …

Stress Analysis Based On Ecg And Eeg, Eyad Talal Attar

Theses and Dissertations

Stress is a significant risk factor for various diseases such as hypertension, heart attack, stroke, and even sudden death. In many studies, stress is linked to decision making, performance, and learning. The heart rate variability (HRV) can be measured from the Electrocardiogram (ECG) and is defined as the variation of the interval between two consecutive heartbeats (heart rate). Heart rate variability is also an indicator of the balance between the sympathetic and parasympathetic branches of the autonomic nervous system. HRV refers to variations of heart rate in a certain amount of time. Heart rate variability (HRV) is a relatively new …

A Comparative Study To Assess The Osteogenic Potential Of Competing Bioceramics For Bone Tissue Engineering, Nashaita Patrawalla

Theses and Dissertations

Biomimetic composite scaffolds comprising of bioactive ceramic-based materials incorporated within a polymeric framework have shown considerable promise for use in bone tissue engineering (BTE) applications. Although bioceramics have shown immense promise for use in BTE, few studies have performed a head-to-head comparison of the osteogenic properties of the most promising bioceramic materials. The goal of this study was to compare three different bioceramics – Bioglass 45S5 (BG), Laponite XLG (LAP), and β-Tricalcium Phosphate (TCP) – on the physical properties (i.e., swelling, stability, compressive modulus, bone bioactivity) of methacrylated collagen (CMA) hydrogels and osteogenic differentiation of human MSCs (hMSCs) encapsulated within …

Validation Of Arterial Distensibility Neural Network Model With Clinical Data, Cassondra Michelle Petersen

Theses and Dissertations

Cardiovascular diseases continue to plague the world as the number one killer of adults each year. As cardiovascular diseases can start with seemingly no symptoms, heart disease has been coined as the silent killer. With the ongoing COVID-19 global pandemic, the need for advances in cardiovascular advances has become even more prevalent as this virus is known to cause more severe damage to those who have underlying cardiovascular problems. These two reasons show the dire clinical need for researchers to continue to use novel techniques such as neural networks to find new approaches for helping physicians non-invasively and quickly add …

Bioink Optimization And Effects Of Microgravity On 3d Bioprinted Cell Laden Constructs, Likitha Somasekhar

Theses and Dissertations

Bioengineered 3D tissue constructs have gained attention as in vitro tools for the study of cell-cell and cell-matrix interactions and are being explored for potential use as experimental models for mimicking human tissues. One of the main problems in tissue engineering is the necessity to vascularize complex engineered tissues and sacrificial printing has been recognized as a possible solution to vascularization of the bioprinted tissues. Research studies have demonstrated that exposure to microgravity in space induces adaptive alterations in vascular structure and function. Changes in the morphology and gene expression is observed when endothelial cells are exposed to microgravity and …

Cardiovascular Intelligence: Novel Quantitative Cardiology, Deep Learning And Machine Learning Models To Predict Clinical Outcomes, Vignesh Balasubramanian

Theses and Dissertations

Arterial compliance has been recognized as a critical parameter in governing pulsatile flow dynamics. It has traditionally been assumed constant throughout the cardiac cycle. Its computation has been based either on the classic Windkessel model in diastole or the stroke volume over pulse pressure method in systole. We proposed a novel compliance-pressure loop (CPP loop) approach to quantify arterial compliance and compare it to existing linear and nonlinear methods. This was followed by an analysis of increased pulse wave reflections in hypertension due to impedance mismatching and how the effective energy transmission to the vasculature is compromised. Their quantification in …

Improving Long-Term Vascular Graft Viability Using Peritoneal Pre-Implantation And Epsin-Mimetic Peptides, Mahyar Sameti

Theses and Dissertations

The primary goal of this project was to produce and develop a tissue-engineered small-diameter vascular graft which can replace the arteries and function well for long-term grafting. Implanting an electrospun tubular conduit into the peritoneal cavity to recruit autologous cells prior to grafting the conduit into the artery is a method to achieve this goal. Incorporating an epsin-mimetic peptide on the conduit prior to grafting is another proposed method to reach the goal. This will be accomplished through four complementary studies: (1) determining the effect of a pouch in peritoneal pre-implantation and reducing the potential peritoneal adhesion formation;(2) determining the …

3d Printed Microporous Collagen Constructs Using The Freeze-Fresh Methodology, Thais Sousa Senzano

Theses and Dissertations

Scaffold microporosity is known to play a critical role in governing cellular response including cell migration, proliferation, and tissue-specific differentiation. While fabrication approaches such as solvent leaching and freeze-casting are commonly used for the generation of microporous biomaterial scaffolds, these methods provide little control over scaffold geometry and creation of complex tissue structures. Extrusion-based 3D printing, an additive manufacturing method, is a highly versatile layer-by-layer printing approach that allows for the fabrication of easily customizable 3D scaffolds with complex architecture using a vast selection of polymeric bioinks. These 3D printed constructs are porous at the macroscale, but achieving microporosity (i.e., < 100 μm) in printed constructs is challenging due to the sub-optimal resolution of the extrusion-based printing method. A recent study using alginate inks introduced a new fabrication technique termed Freeze-FRESH(FF)that combines extrusion printing and freeze-casting approaches to generate 3D constructs with hierarchical microporosity. However, the porosity of the resultant alginate constructs was comparable despite changing the freezing temperature. In the current study, the FF method was modified to print collagen constructs with greater control of microporous architecture. Highly concentrated collagen type I ink was used to 3D print collagen constructs using the freeform reversible embedding of suspended hydrogels (FRESH)approach. Modification of the FF technique entailed melting of the FRESH bath post printing via incubation at 37 °C followed by freezing and lyophilization to allow for collagen gelation and better heat transport during the freezing process. The effect of freezing temperature on micropore size, swelling degree, degradation, and mechanical properties of printed constructs was assessed. Finite element (FE) models were generated to predict the mechanical properties of microporous scaffolds. In addition, the effect of microporosity on Saos-2 cell morphology, proliferation, infiltration, and ALP activity was evaluated. Results from the study showed that freezing temperature effectively modulated micropore size and that constructs with larger micropore size were more stable. Microporosity had no effect on swelling ratio yet caused a decrease in mechanical properties of collagen constructs; FE models confirmed experimental results. Cell metabolic activity and infiltration was enhanced in microporous constructs with larger pore size, yet there was no effect on cell morphology, and ALP activity. In conclusion, the modified FF technique can be effectively used to fabricate hierarchically porous 3D collagen constructs.

An Experimental And Computational Mechanical Analysis Of Bone Anchors And Substrate Interface, Samantha May Schultz

Theses and Dissertations

Screw loosening is a common concern in orthopedic surgery. Therefore, this study is a computational and experimental evaluation of bone substrate and cortical screw interface. An axial load test was performed in an Instron with titanium alloy screws with 2.7 mm, 3.5 mm, and 4.5mm diameter orthopedic cortical screws inserted into SawBone with densities varying from 10 to 50 pounds per cubic foot (PCF), incrementing in sets of 10 PCF. SawBone was chosen in place of human bone because it has been shown to emulate the same mechanical properties (1). Twelve samples were prepared for each screw size and substrate …

Development Of A Graphical User Interface For Ecg Signals Classification Using Statistical Features Analysis, Mousa Hammad S Aldosari

Theses and Dissertations

Cardiac diseases are the most common cause of mortality in the world. The detection of cardiac arrhythmias is not a straightforward process, since minor variations in the electrocardiogram (ECG) signals cannot be easily identified manually. Therefore, automatic detection and classification of cardiac arrhythmia would shorten the diagnostic time and accelerate medical intervention resulting in reducing the mortality rate. In this thesis, I have developed a simple and low-cost computer-aided diagnostic system using MATLAB-based Graphical User Interface (GUI) to facilitate fast operation and access to the data along with the overall accuracy of the system. The acquired ECG signals are processed …

Mechanical And Material Properties Of Nitinol And Its Application To Stents, Ariana Solis Eichler

Theses and Dissertations

Nitinol is a functional material with superelastic and shape memory properties derived from its unique molecular structure. The purpose of this thesis is to explore how the material and mechanical properties of self-expanding Nitinol stents affects the forces applied to arterial walls during stent deployment compared to the traditional balloon-expanding stainless steel stents, in addition to contrasting thin and thick-walled pressure vessel mathematical models. Nitinol’s mechanical properties can be optimized for stent applications by tailoring its processing procedures. Nitinol stents demonstrated a reduced circumferential hoop stress on the vessel wall and greater factor of safety with respect to vessel rupture …

Development Of A Novel System For The Analysis Of The Cardiovascular And Autonomic Nervous Systems, Seyedmohsen Dehghanojamahalleh

Theses and Dissertations

Chapter 1 - An introduction to autonomic nervous system (ANS) and cardiovascular system (CVS): The performance of the ANS can be evaluated by quantizing the changes made by the autonomic nervous system. The most common parameters that are being used in autonomic nervous system assessment tests are blood pressure, heart rate, pressure pulse wave velocity, heart rate variability, and pulse waveform. In this dissertation, we designed and developed a system that assesses the activity of these two systems. Therefore, we represented four methods to 1- evaluate the dependence of neuro- and cardiovascular systems on sex, 2- non-invasively estimate the blood …

Controlling Co Dose From Corm-Loaded Electrospun Scaffolds With Diffusion-Based Modeling And Experimental Assessment Of Endothelial Cell Response, Kenyatta S. Washington

Theses and Dissertations

Cardiovascular disease (CVD) accounts for one in every five deaths in the United States alone due to occlusion in small diameter (< 6 mm) vessels. The current treatment options includes bypass grafting; however, more than 30 percent of patients do not have viable saphenous veins for autologous grafting [1]. Therefore, tissue engineering is being considered as an alternative approach. The overall goals of this project were to develop a tissue engineered vascular graft with the incorporation of carbon monoxide releasing molecules (CORMs) and to determine the impacts of carbon monoxide (CO) on endothelial cells (ECs) with the goal of promoting a functional endothelium within the graft. This was accomplished through two complementary studies: investigating the impacts of CO-loaded electrospun scaffolds on ECs for cardiovascular applications and diffusion-based modeling of drug delivery of gasotransmitters from tissue engineered scaffolds. In the first study, we extended the maximum in vitro incubation time to permit better cellular attachment and proliferation with a newly-synthesized, more hydrophobic CORM (DK3) and established the impact of CORMs on EC viability and function (e.g. reactive oxygen species (ROS) products, and ROS levels). We further investigated toxicity and biocompatibility of a newly synthesized CORM (DK4) loaded within PCL thin films and nanoparticles. We concluded that the DK4 and other compounds are not toxic at doses ranging from 0 – 50 μg/mL to the ECs both within nanoparticles that can be internalized within cells. We also conducted an in vivo pilot study to determine graft biocompatibility and preliminary results showed that CORM implants maintain mechanical integrity, support blood flow, and do not show toxicity for up to six weeks. In the second study, we validated a computational model and analyzed the output of CO delivery to better understand and control local dose. For CO release, this model is necessary because of the limitations with real-time experimental analysis and the need to better understand the dose available to the cells. We demonstrated that the validated model can be used to predict drug availability to cells for a variety of scaffolds and drug molecules. Our simulated results suggest that only a fraction of the initial concentration of gasotransmitters released from fibers that enters the interstitial fluid in vivo, or culture media in vitro, will be available to cells. We also demonstrated that fiber orientation and fiber diameter are important for drug delivery, but fiber density provides even more important information. The more contact area within the fiber scaffolds is equivalent to experimental conditions with more cell attachment and spreading. These parameters are not only important for traditional tissue engineering, but also for drug delivery. Overall, these results demonstrate the feasibility of making a tissue engineered vascular graft with the incorporation of CORMs and validating he importance of computational modeling of diffusion-based transport of CO. Future work will involve performing surface modifications to enhance cell attachment and proliferation, using the developed computational model to better predict dose available to cells, and experimentally determining impact of CO dose on ECs.

Gene Expression Studies For Analyzing Effects Of Space Radiation In Tissues, Amatulshakoor Mohammed Farooqui

Theses and Dissertations

Human exploration beyond the earth's orbit poses many risks for the crew on these missions. One of the major health risks is exposure to space radiation environment beyond the earth’s magnetic field. The space environment exposes astronauts to high levels of ionizing radiation such as galactic cosmic rays. The radiations can have acute and delayed effects on the human body. The primary response to tissue injury is increased oxidative stress and inflammation. The overall objective of this study was to analyze the effects of ionizing radiation in heart tissue by quantifying its impact on the expression of genes that correlate …

Bioprinting Of 3d Perfusable Structures Using An Extrusion-Based System, Prabhuti Kharel

Theses and Dissertations

Bioprinting is a technique of creating 3D cell laden structures by accurately dispensing biomaterial to form complex synthetic tissue. Bioprinting is a process of additive manufacturing where the cell functionality and viability is preserved within the printed structure. Bioprinting is a promising alternative to produce physiologically relevant 3D structures that mimic the native tissue. However, fabrication of complex structures with vascularization has been a major challenge in bioprinting. To overcome this challenge sacrificial printing in combination with fugitive inks has been explored to create vascularize structures. The objective of this study is to fabricate hollow channels within the bioprinted structure …

Hrv - Ecg Generator: Software For Testing Heart Rate Variability Detection, Matthew Joseph Pogorelec

Theses and Dissertations

Heart rate variability (HRV) has been shown to serve as an effective diagnostic and prognostic tool in a variety of clinical applications, including for patients who have suffered from myocardial infarction, sepsis and liver cirrhosis. There currently exist a variety of devices and software to quantify HRV based on RR interval series collected from ECG data. However, as the uses for HRV expand, a greater variety of devices for different applications are being designed and developed. Thus, it is useful to have available a method for efficiently testing preliminary software. The HRV/ECG Generator software is designed to build both an …