Biomedical Engineering and Bioengineering Commons^™

Surface Modification Of Traditional And Bioresorbable Metallic Implant Materials For Improved Biocompatibility, Emily Kristine Walker

Open Access Dissertations

Due to their strength, elasticity, and durability, a variety of metal alloys are commonly used in medical implants. Traditionally, corrosion-resistant metals have been preferred. These permanent materials can cause negative systemic and local tissue effects in the long-term. Permanent stenting can lead to late-stent thrombosis and in-stent restenosis. Metallic pins and screws for fracture fixation can corrode and fail, cause loss of bone mass, and contribute to inflammation and pain at the implant site, requiring reintervention. Corrodible metallic implants have the potential to prevent many of these complications by providing transient support to the affected tissue, dissolving at a rate …

A Three Constituent Mixture Theory Model Of Cutaneous And Subcutaneous Tissue In The Context Of Neonatal Pressure Ulcer Etiology And Prevention, Anne Dye Zakrajsek

Open Access Dissertations

Localized ischemia, impaired interstitial fluid flow, and sustained mechanical loading of cells have all been hypothesized as mechanisms of pressure ulcer (PrU) etiology. Time-varying loading has experimentally been shown to increase fluid flow in human skin in vivo. Towards the design of prophylactic protocols and treatment modalities for PrU management there is a need for an analytical model to investigate the local fluid flow characteristics of skin tissue under time-varying loading. In this study, a triphasic mixture theory model with constituents of extracellular matrix, interstitial fluid, and blood was calibrated and validated and used to investigate stress and fluid velocity …

Unveiling The Mechanical Behavior Of The Rod-Like Microstructure In The Radular Teeth Of Cryptochiton Stelleri, Enrique Escobar De Obaldia

Open Access Dissertations

Natural ceramics provided with high volume fractions of mineralized materials that are surrounded by a weak organic interface combine the stiff mechanical behavior of building blocks, like hydroxyapatite or aragonite, and the compliance of the organic surroundings. Unique mechanical properties (e.g. light density and toughness) distinguish bio-composites from common engineering materials. A key example is the highly mineralized shell of the radular teeth of the Crypochiton stelleri. Nature has provided the radular teeth with a highly oriented rod-like microstructure of nano-scale dimensions embedded in a matrix of chitin sheaths. Compared to other biological materials, the external iron oxide layer of …

Cerebrovascular Reactivity Alterations Due To Subconcussive Repetitive Head Trauma In Asymptomatic High School Football Players, Chetas Joshi

Open Access Theses

Chronic neurological damage as a result of chronic repetitive head trauma is a major concern for football athletes today. Repetitive concussions have been linked to many neurological disorders. Recently, it has been reported that repetitive subconcussive events can contribute to long-term neurodegeneration. For these reasons, it is important to understand the effect repetitive subconcussive head trauma has on brain health in young athletes. Past research has demonstrated that cerebrovascular reactivity (CVR), an important mediator of cerebrovascular regulation, is impaired following mild traumatic brain injury (mTBI). This impairment increases susceptibility to secondary injury following mTBI. In this study, Breath-Hold (BH) task …

Instrumentation And Development Of A Mass Spectrometry System For The Study Of Gas-Phase Biomolecular Ion Reactions, Ziqing Lin

Open Access Dissertations

Gas-phase reactions of biomolecular ions are highly relevant to the understanding of structures and functions of the biomolecules. Mass spectrometry is a powerful tool in investigating gas-phase ion chemistry. Various mass spectrometers have been developed to explore ion/molecule reactions, ion/ion reactions, ion/photon reactions, ion/radical reactions etc., both at atmospheric pressure and in vacuum. In-vacuum reactions have an advantage of involving pre-selecting the ions for the reactions using a mass analyzer. Over the decades, a variety of mass analyzers have been employed in the research of ion chemistry. Hybrid configurations, such as quadrupole ion trap with a time-of-flight and or a …

Optimizing Strategies For Population-Based Chlamydia Infection Screening Among Young Women: An Age-Structured System Dynamics Approach Infectious Disease Epidemiology, Yu Teng, Nan Kong, Wanzhu Tu

Weldon School of Biomedical Engineering Faculty Publications

Background

Chlamydia infection (CT) is one of the most commonly reported sexually transmitted diseases. It is often referred to as a “silent” disease with the majority of infected people having no symptoms. Without early detection, it can progress to serious reproductive and other health problems. Economical identification of asymptomatically infected is a key public health challenge. Increasing evidence suggests that CT infection risk varies over the range of adolescence. Hence, age-dependent screening strategies with more frequent testing for certain age groups of higher risk may be cost-saving in controlling the disease.

Methods

We study the optimization of age-dependent screening strategies …

The Origin Of Korotkoff Sounds And The Accuracy Of Auscultatory Blood Pressure Measurements, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

This study explores the hypothesis that the sharper, high frequency Korotkoff sounds come from resonant motion of the arterial wall, which begins after the artery transitions from a buckled state to an expanding state. The motion of one mass, two nonlinear springs, and one damper, driven by transmural pressure under the cuff, are used to model and compute the Korotkoff sounds according to principles of classical Newtonian physics. The natural resonance of this spring-mass-damper system provides a concise, yet rigorous, explanation for the origin of Korotkoff sounds. Fundamentally, wall stretching in expansion requires more force than wall bending in buckling. …

Ontogenetic Scaling Patterns And Functional Anatomy Of The Pelvic Limb Musculature In Emus (Dromaius Novaehollandiae), Luis P. Lamas, Russell P. Main, John R. Hutchinson

Department of Basic Medical Sciences Faculty Publications

Emus (Dromaius novaehollandiae) are exclusively terrestrial, bipedal and cursorial ratites with some similar biomechanical characteristics to humans. Their growth rates are impressive, as their body mass increases eighty-fold from hatching to adulthood whilst maintaining the same mode of locomotion throughout life. These ontogenetic characteristics stimulate biomechanical questions about the strategies that allow emus to cope with their rapid growth and locomotion, which can be partly addressed via scaling (allometric) analysis of morphology. In this study we have collected pelvic limb anatomical data (muscle architecture, tendon length, tendon mass and bone lengths) and calculated muscle physiological cross sectional area …

Algorithm-Circuit Co-Design For Detecting Symptomatic Patterns In Biological Signals, Himanshu Markandeya

Open Access Dissertations

The advancement in scaled Silicon technology has accelerated the development of a wide range of applications in various fields including medical technology. It has immensely contributed to finding solutions for monitoring general health as well as alleviating intractable disorders in the form of implantable and wearable systems. This necessitates the development of energy efficient and functionally efficacious systems. This thesis has explored the algorithm-circuit co-design approach for developing an energy efficient epileptic seizure detection processor which could be used for implantable epilepsy prosthesis. Novel wavelet transform based algorithms are proposed for accurate detection of epileptic seizures. Energy efficient techniques at …

Effects Of Hip And Ankle Moments On Running Stability: Simulation Of A Simplified Model, Rubin C. Cholera

Open Access Theses

In human running, the ankle, knee, and hip moments are known to play different roles to influence the dynamics of locomotion. A recent study of hip moments and several hip-based legged robots have revealed that hip actuation can significantly improve the stability of locomotion, whether controlled or uncontrolled. Ankle moments are expected to also significantly affect running stability, but in a different way than hip moments. Here we seek to advance the current theory of dynamic running and associated legged robots by determining how simple open-loop ankle moments could affect running stability. We simulate a dynamical model, and compare it …

Principle Of Bio-Inspired Insect Wing Rotational Hinge Design, Fan Fei

Open Access Theses

A principle for designing and fabricating bio-inspired miniature artificial insect flapping wing using flexure rotational hinge design is presented. A systematic approach of selecting rotational hinge stiffness value is proposed. Based on the understanding of flapping wing aerodynamics, a dynamic simulation is constructed using the established quasi-steady model and the wing design. Simulations were performed to gain insight on how different parameters affect the wing rotational response. Based on system resonance a model to predict the optimal rotational hinge stiffness based on given wing parameter and flapping wing kinematic is proposed. By varying different wing parameters, the proposed method is …

Synthesis Of Multilayered Microparticles For Targeted Drug Delivery, Elizabeth Mercer

Open Access Theses

Microparticles have been shown to be valuable in targeted drug delivery which can lead to an increased dose delivered to a targeted location, reduced patient side effects, and improved patient outcomes. The designed multilayered microparticles have the clinical application to deliver hydrophobic drugs to a targeted area. The composition of the microparticles consists of a poly-lactic acid (PLA) polymer core surrounded by a polymeric shell composed of Poly(lactic-co-glycolic acid)-Poly(ethylene glycol)-Maleimide(PLGA-PEG-Mal). The maleimide promotes conjugation of the collagen binding peptide, SILY. Targeting to type I collagen allows for this microparticle system to attach to exposed collagen in atherosclerotic vessels.

A novel …

Probabilistic Uncertainty Quantification And Experiment Design For Nonlinear Models: Applications In Systems Biology, Vu Cao Duy Thien Dinh

Open Access Dissertations

Despite the ever-increasing interest in understanding biology at the system level, there are several factors that hinder studies and analyses of biological systems. First, unlike systems from other applied fields whose parameters can be effectively identified, biological systems are usually unidentifiable, even in the ideal case when all possible system outputs are known with high accuracy. Second, the presence of multivariate bifurcations often leads the system to behaviors that are completely different in nature. In such cases, system outputs (as function of parameters/inputs) are usually discontinuous or have sharp transitions across domains with different behaviors. Finally, models from systems biology …

Hierarchical Cell Fluid Extracellular Matrix Interaction In Cell Microenvironment, Soham Ghosh

Open Access Dissertations

Hierarchical structural interactions between components of cell microenvironment, the extracellular matrix (ECM), cytoplasm, nucleus and fluid, are important phenomena that decide cell level physiological process and tissue engineering applications. One of those tissue engineering modalities is freezing of biomaterials, important in a wide variety of biomedical applications including cryopreservation and cryosurgeries. In order to design these applications, freezing-induced changes of the cells and tissues and corresponding biophysical mechanisms need to be well understood. Although the effects of freezing on cells in suspension have been extensively studied, the intracellular mechanics of cells embedded in the extracellular matrix (ECM) during freezing are …

Intranuclear Strain Measured By Iterative Warping In Cells Under Mechanical And Osmotic Stress, Jonathan T Henderson

Open Access Dissertations

The nucleus is a membrane bound organelle and regulation center for gene expression in the cell. Mechanical forces transfer to the nucleus directly and indirectly through specific cellular cytoskeletal structures and pathways. There is increasing evidence that the transferred forces to the nucleus orchestrate gene expression activity. Methods to characterize nuclear mechanics typically study isolated cells or cells embedded in 3D gel matrices. Often report only aspect ratio and volume changes, measures that oversimplify the inherent complexity of internal strain patterns. This presents technical challenges to simultaneously observe small scale nuclear mechanics and gene expression levels inside the nuclei of …

Development Of Planar Patch Clamp With Potentiometric Calcium Ion-Selective Electrode, Kul Inn

Open Access Dissertations

Ion channels are proteins in cell lipid bilayer membranes and act as pores which can adopt closed and open states, thus gating the flow of ions in and out of the cell. Patch clamp technology has been the proven standard for fundamental studies of ion channel activities. However, the technique has some basic limitations: low throughput, time consuming nature of its process, need of highly skilled personnel and inability to identify ionic composition of electrophysiological events. Many different materials and fabrication methods have been introduced to replace traditional patch clamp setup to overcome limitations.^ In this dissertation, a planar patch …

Theory For Diffusional Encounters In Heterogeneous Environments And Multivalent Electrolyte Screening Of Charged Interface, Ran Li

Open Access Dissertations

We develop a theory for encounter rates in a three-dimensional system of connected compartments. The model of connected compartments exhibits the length-scale dependent diffusion that is observed in many heterogeneous environments, such as porous catalysts and biological environments. We discovered a dimensionless number that is the dominant scaling variable and obtained, for the first time, an analytical expression for the encounter rate. The new theory generalizes the classic Smoluchowski diffusion limit to the case of heterogeneous environments. The new theory is tested using Brownian dynamics simulations.^ We also experimentally investigated the behavior of multivalent electrolyte near a charged solid-liquid interface. …

Acrolein As A Novel Therapeutic Target For Spinal Cord Injury Induced Neuropathic Pain, Jonghyuck Park

Open Access Dissertations

Despite years of research, post-spinal cord injury (SCI) chronic neuropathic pain remains refractory to treatment and drastically impairs quality of life for SCI victims beyond paralysis. Although inflammation and free radicals contribute to neuropathic pain in SCI, the mechanism is not completely clear. We have recently demonstrated that acrolein, a product and catalyst of lipid peroxidation, induces a vicious cycle of oxidative stress, amplifying its effects and perpetuating oxidative stress and inflammation. In the current study, we have confirmed that acrolein is elevated significantly at least two weeks post-SCI which coincides with the emergence of hyperalgesia (mechanical, cold and thermal). …

Structure-Functionality Relationship Of Collagen Scaffolds For Tissue Engineering, Seungman Park

Open Access Dissertations

Tissue engineering is a promising technology that enables scientists to create artificial organs or replace damaged tissues using animal cells and other components. For successful tissue regeneration, many factors should be taken into account, however, three components are most crucial: cell, scaffold, and soluble factor(s). In order to check the functionality after regeneration of desired tissues, various approaches have been attempted, depending on the physical, biological, and chemical properties of the tissues. Recently, the importance of the extracellular matrix (ECM) microstructure is being considered to be important in this regard. The ECM is closely associated with various functional properties of …

Development Of A Static Bioactive Stent Prototype And Dynamic Aneurysm-On-A-Chip(Tm) Model For The Treatment Of Aneurysms, Lisa M. Reece

Open Access Dissertations

Aneurysms are pockets of blood that collect outside blood vessel walls forming dilatations and leaving arterial walls very prone to rupture. Current treatments include: (1) clipping, and (2) coil embolization, including stent-assisted coiling. While these procedures can be effective, it would be advantageous to design a biologically active stent, modified with magnetic stent coatings, allowing cells to be manipulated to heal the arterial lining. Further, velocity, pressure, and wall shear stresses aid in the disease development of aneurysmal growth, but the shear force mechanisms effecting wound closure is elusive. Due to these factors, there is a definite need to cultivate …

Understanding Preferred Leg Stiffness And Layered Control Strategies For Locomotion, Zhuohua H. Shen

Open Access Dissertations

Despite advancement in the field of robotics, current legged robots still cannot achieve the kind of locomotion stability animals and humans have. In order to develop legged robots with greater stability, we need to better understand general locomotion dynamics and control principles. Here we demonstrate that a mathematical modeling approach could greatly enable the discovery and understanding of general locomotion principles. ^ It is found that animal leg stiffness when scaled by its weight and leg length falls in a narrow region between 7 and 27. Rarely in biology does such a universal preference exist. It is not known completely …

Biological Implications Of Satellite Cells For Scaffold-Based Muscle Regenerative Engineering, Maggie R. Del Ponte, Charter Chain, Meng Deng Dr., Feng Yue Dr., Shihuan Kuang Dr.

The Summer Undergraduate Research Fellowship (SURF) Symposium

Satellite cells are anatomically localized along the surface of muscle fibers and have been regarded as a population of muscle-specific progenitors that are responsible for muscle regeneration. In response to muscle injuries, satellite cells are activated to enter the cell cycle, then proliferate and differentiate into mature muscle cells to regenerate damaged myofibers. Unfortunately, this natural repair mechanism is interrupted in conditions such as muscle degenerative diseases or volumetric muscle loss. The function of stem cells is regulated by signals from their local microenvironment which is called the stem cell niche. Current satellite cell-based strategies such as direct cell transplantation …

Using Collagen Binding Poly(N-Isopropylacrylamide) Nanoparticles To Prevent Intravascular Platelet Adhesion And Activation, Anna E. Searle, Alyssa Panitch, James Mcmasters

The Summer Undergraduate Research Fellowship (SURF) Symposium

Balloon angioplasty, the most prevalent non-surgical treatment for Atherosclerosis, damages the endothelial layer of the artery, baring an underlying collagenous layer, which causes platelet adhesion and activation and eventual thrombosis and intimal hyperplasia. Previous work in our lab has used a collagen-binding peptidoglycan, dermatan-sulfate-SILY (DS-SILY), that has been shown to bind to type I collagen and prevent platelet adhesion and activation. Our goal is to fabricate nanoparticle-SILY by cross-linking SILY to a poly(N-isopropylacrylamide) (NIPAm) nanoparticle instead of a DS backbone, while retaining the SILY’s high collagen binding affinity and platelet inhibition capacity observed in DS-SILY. Using a biotin-streptavidin assay, we …

Optimization Of Imaging Parameters To Determine Flow Velocity Using Nanoparticles, Sabrina M. Scalf, Haisheng Yang, Russell P. Main

The Summer Undergraduate Research Fellowship (SURF) Symposium

Microfluidic flow chambers have been developed and used to measure flow at the microscopic level. Nanoparticles can be used to track the fluid flow within the chamber and this allows for accurate velocity measures. Microscope parameters used for experimentation differ across various projects and resources; therefore, there is a need to determine the best combination of settings for the equipment at hand. Once appropriate settings are selected, images of the flow are captured with a confocal microscope and can be analyzed using custom written MATLAB code. A pair cross-correlation function is used to determine where the particles have traveled in …

Spatiotemporal Changes In Nuclear Strain Measured By Traction Force Microscopy, Ryan D. Watts, Corey Neu, Jonathan Henderson

The Summer Undergraduate Research Fellowship (SURF) Symposium

The knowledge of how cells interact with and sense their surroundings is missing the key components of time dependency and how substrate stiffness affects amount and rate of strain. This new knowledge of cell-substrate interaction can be applied further to research regarding chromatin spatiotemporal dynamics to better understand gene accessibility for transcription. Studying how the cell functions on a deeper level will provide understanding of cellular morphological changes and proliferation. This study uses the methods of optical microscopy and traction force microscopy (TFM) to image substrate deformation as well as analyze its strain profile to find where forces are interacting …

Thin-Film Sol-Gel As Controlled Delivery Platform For Neural Microelectrodes, Margaret A. Harden, Matthew D. Mcdermott, Kevin J. Otto

The Summer Undergraduate Research Fellowship (SURF) Symposium

Long-term efficacy of neural implantation devices is a persisting challenge in neural engineering and rehabilitation. Upon implantation of a neural device, the foreign body response (FBR) is triggered and glial cells form a sheath around the electrode array. This sheath isolates the array from the rest of the brain both mechanically and electrically. Tetramethyl orthosilicate (TMOS), a thin-film polymer, has been shown to not negatively impact the impedance and charge-carrying capacity, as well as offer a controlled delivery method to deliver pharmaceuticals to mitigate inflammation without significant effect to device design. Using an in vitro protein delivery model to analyze …

Tissue Engineering: Applications In Developmental Toxicology, Stephanie N. Thiede, Nimisha Bajaj, Kevin Buno, Sherry L. Voytik-Harbin

The Summer Undergraduate Research Fellowship (SURF) Symposium

In vivo toxicology assays are expensive, low-throughput, and often not predictive of a human response. Three-dimensional in vitro human cell-based tissue systems incorporating cell-cell and cell-matrix interactions have promise to provide high-throughput, physiologically-relevant information on the mechanism of the toxin and a more accurate assessment of the toxicity of a chemical before progression to human trials. Quantification of the disruption of vasculogenesis, the de novo formation of blood vessels from endothelial progenitor cells, can serve as an appropriate indicator of developmental toxicity since vasculogenesis is critical to the early development of the circulatory system. The current routinely used in vitro …

Multi-Channel Analysis For Gradient Artifact Removal From Concurrent Eeg-Fmri Studies, Miguel R. Castellanos, Zhongming Liu

The Summer Undergraduate Research Fellowship (SURF) Symposium

Concurrent electroencephalogram (EEG) and functional magnetic resonance imaging (fMRI) recordings are susceptible to large amounts of noise due to the static and dynamic magnetic fields present inside the MR scanner. EEG-fMRI studies are conducted to provide better spatial and temporal resolution for each recording, respectively, but the artifacts found in the EEG render the data impossible to interpret. Past studies have focused on signal post-processing techniques which are able to effectively remove noise upon the completion of a study, but there are no techniques able to process the data in real-time without extensive calibration. This research addresses this issue by …

Medical Applications Of Mrc, Kyle Thackston, Henry Mei, Pedro Irazoqui

The Summer Undergraduate Research Fellowship (SURF) Symposium

Consistent powering is a limiting reagent for many medical implants and sensors. Powering in-vivo devices in animal studies requires either transcutaneous wiring (limiting mobility and increasing the chance of infection) or an implanted battery (limited lifetime and limits size of device). Wireless power transfer (WPT) would be able to overcome these challenges and permit the use of more advanced implantable devices in a research setting. Magnetic resonance coupling (MRC), an advanced form of inductive charging, allows good transfer efficiencies over significant air gaps, but works best a specific location and frequency, limiting mobility in animal studies. Using band-pass filter theory, …

Three Dimensional Quantification Of Angiotensin Ii-Induced Murine Abdominal Aortic Aneurysms Using High Frequency Ultrasound, Amelia R. Adelsperger, Alexa A. Yrineo, Hilary D. Schroeder, Ashley Nicole Blaize, Katherine E. Wilson, Evan H. Phillips, Frederick W. Damen, Craig J. Goergen

The Summer Undergraduate Research Fellowship (SURF) Symposium

Abdominal aortic aneurysms (AAAs), a localized dilation of the vessel wall of 50% or more above normal, claims approximately 14,000 U.S. lives yearly due to aortic rupture. This commonly asymptomatic disease can only be treated by endovascular stent grafts or invasive surgery, usually after the AAA diameter reaches 5 cm. Because these treatment methods carry serious risk, stem cell therapy is being explored in order to provide a low risk option for managing smaller AAAs. To determine if stem cell therapy, once administered, could stabilize or reduce AAA growth, baseline 3D ultrasound measurements in a control group were first needed. …