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Articles 1 - 9 of 9
Full-Text Articles in Biomechanical Engineering
Multiscale Architecture Governs Stability In Suction-Actuated Variable Stiffness Catheters, Sheridan Lee
Multiscale Architecture Governs Stability In Suction-Actuated Variable Stiffness Catheters, Sheridan Lee
McKelvey School of Engineering Graduate Student Theses & Dissertations
Endovascular procedures require devices with widely varying mechanical properties: flexibility for navigating tortuous vessels and rigidity for stable therapeutic delivery. Suction-actuated variable stiffness sheaths address this challenge by incorporating axial wire string arrays that mechanically couple under suction to increase flexural rigidity. However, prototype devices achieve stiffening ratios below theoretical predictions, suggesting that interlayer mechanics and string positioning play a critical role. This study investigates whether interweaving polytetrafluoroethylene (PTFE) tape within the string array enhances flexural rigidity modulation and curvature stability. Prototype devices with varying wrap configurations were fabricated and evaluated using flexural testing, curvature stability testing, and mathematical modeling. …
Expansion Limits Of Meshed Split-Thickness Skin Grafts, Haomin Yu
Expansion Limits Of Meshed Split-Thickness Skin Grafts, Haomin Yu
McKelvey School of Engineering Graduate Student Theses & Dissertations
Split-thickness skin grafts are widely used to treat chronic wounds. Procedure design requires surgeons to predict how much a patch of the patient's own skin expands when it is meshed with rows of slits and stretched over a larger wound area. Accurate prediction of graft expansion remains a challenge, with current models overestimating the actual expansion, leading to suboptimal outcomes. Inspired by the principles of mechanical metamaterials, we developed a model that distinguishes between the kinematic rearrangement of structural elements and their stretching, providing a more accurate prediction of skin graft expansion. Our model was validated against extensive data …
Environment And Response Of 3d-Encapsulated Mesenchymal Stem Cells To Mechanical Loading, Augustus Greenwood
Environment And Response Of 3d-Encapsulated Mesenchymal Stem Cells To Mechanical Loading, Augustus Greenwood
McKelvey School of Engineering Graduate Student Theses & Dissertations
This thesis explores the micromechanical environment induced when cyclically compressing hydrogels via finite element modeling and experimentally on the impact of loading on mesenchymal stem cells (MSCs) when encapsulated withing 3D hydrogel matrices. Degenerative joint diseases, characterized by cartilage degradation, present significant challenges due to cartilage's limited self-repair capacity. Innovative approaches, including stem cell-based therapies and engineered biomaterials, have emerged as promising strategies for cartilage repair and regeneration. This work specifically investigates the calibration of a bioreactor, the uniformity of load response across the hydrogel constructs via finite element modeling (FEM), and the stress response of MSCs subjected to various …
Engineered Material Systems For Mimicking Tissue And Disease, Margrethe Ruding
Engineered Material Systems For Mimicking Tissue And Disease, Margrethe Ruding
McKelvey School of Engineering Graduate Student Theses & Dissertations
This thesis comprises two studies involving design and application of soft material systems. The goal of the first study was to design, fabricate, and characterize hydrogel lattice structures with consistent, controllable, anisotropic mechanical properties. Lattices, based on four types of unit cells (cubic, diamond, vintile, and Weaire-Phelan), were printed using stereolithography (SLA) of polyethylene glycol diacrylate (PEGDA). In order to create structural anisotropy in the lattices, unit cell design files were scaled in one direction by a factor of two in each layer and then printed. The mechanical properties of the scaled lattices were measured in shear and compression and …
Hemodynamic Effects On Aortic Development Due To Outflow Tract Banding, Humza Ismail
Hemodynamic Effects On Aortic Development Due To Outflow Tract Banding, Humza Ismail
McKelvey School of Engineering Graduate Student Theses & Dissertations
Hemodynamic forces drive remodeling of the early cardiac system in embryonic development. Perturbations of normal cardiac blood flow can cause the formation of defects and malformations within the cardiac system. Specifically, changes in hemodynamics can cause the formation of different congenital heart defects. The formation of heart defects has been studied; however, vasculature specific defects caused by changes in blood flow patterns in the early cardiac system have not been studied to the same degree. In this thesis, the effects of hemodynamic changes on arterial development were studied. Outflow tract banding (OTB) was used to cause a local increase in …
Modeling Of Swimming Cells From Nano-Scale To Micro-Scale, Yicheng Zhao
Modeling Of Swimming Cells From Nano-Scale To Micro-Scale, Yicheng Zhao
McKelvey School of Engineering Graduate Student Theses & Dissertations
Certain human genetic diseases -- primary ciliary dyskinesia, infertility, and hydrocephalus -- are characterized by changes in beat frequency and waveform of cilia and flagella. Chlamydomonas reinhardtii, which is a single-cell green alga about ten micrometers in diameter that swims with two flagella, serves as an excellent biological model because its flagella share the same structure and genetic background as mammalian cilia and flagella. This study uses the finite element method to investigate the behavior of C. reinhardtii swimming from nano-scale to micro-scale. At the device-level, micro-scale modeling indicates that well-designed acoustic microfluidic devices can be used to trap groups …
Tortuosity Calculations, Blood Flow Simulations, And Mechanical Testing Of Mouse Aortae, Shawn Pavey, Jessica Wagenseil
Tortuosity Calculations, Blood Flow Simulations, And Mechanical Testing Of Mouse Aortae, Shawn Pavey, Jessica Wagenseil
Undergraduate Research Symposium Posters
Aortic aneurysms can lead to wall rupture or dissection, which are both deadly occurrences. The risk of developing problematic aneurysms increases with age, making them a growing concern in the USA’s aging population. Thoracic Aortic Aneurysm (TAA) treatment is highly effective if the TAA is diagnosed in time, however current surgical guidelines catch less than half of fatal TAA cases. Tortuosity (related to vessel length divided by the straight distance between two points of interest) has been proposed as a supplement to diameter based diagnosis of severity of TAA progression. This study aimed to confirm the validity of that proposal …
Application Of Pca To Cardiac Optical Mapping, Louis Woodhams
Application Of Pca To Cardiac Optical Mapping, Louis Woodhams
McKelvey School of Engineering Graduate Student Theses & Dissertations
Structural remodeling of the heart due to pathologies such as hypertension and myocardial infarction leads to the appearance of myofibroblasts, a phenotype largely absent in physiologic myocardium. While myofibroblasts are responsible for wound healing and structural repair of damaged myocardium, they are thought to have deleterious effects on electrical and mechanical properties of the heart. Understanding these effects is critical to developing effective treatments, and has motivated the development of a series of in vitro engineered heart tissues and cardiomyocyte-myofibroblast co-cultures whose mechanical and electrophysiological function can be deduced from video analysis. Electrophysiological properties are evident from changes in intensity …
Optimization Of Blalock-Taussig Shunt And Anastomotic Geometry For Vascular Access Fistula Using A Genetic Algorithm, Guangyu Bao
Optimization Of Blalock-Taussig Shunt And Anastomotic Geometry For Vascular Access Fistula Using A Genetic Algorithm, Guangyu Bao
McKelvey School of Engineering Graduate Student Theses & Dissertations
Blalock-Taussig (BT) shunts are used for defects that affect the flow of blood from the right ventricle, through the pulmonary artery, and to the lungs. Arteriovenous (AV) fistula is one type of vascular access which is a surgically created vein used to remove and return blood during hemodialysis. Plastic grafts used in the above two reconstructions may result in areas of non-physiologic flow in the grafts leading to risk of stenosis (blocked area) and thrombosis, which is the single major cause for access morbidity. The focus of this thesis is to study BT shunts and anastomoses models using Computational Fluid …