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Full-Text Articles in Biomedical Engineering and Bioengineering

Thermal Fusion For Sutureless Closure: Devices, Composition, Methods, Eric Anthony Kramer Jan 2018

Thermal Fusion For Sutureless Closure: Devices, Composition, Methods, Eric Anthony Kramer

Mechanical Engineering Graduate Theses & Dissertations

As minimally invasive surgical techniques progress, the demand for reliable ligation is pronounced. The surgical advantages of energy-based vessel sealing exceed those of traditional, compression-based ligatures in procedures sensitive to duration, foreign bodies, and recovery time alike. While the use of energy-based devices to seal or transect vasculature and connective tissue bundles is widespread, the breadth of heating strategies and energy dosimetry used between devices underscores an uncertainty as to the molecular nature of the sealing mechanism and induced tissue bond. Further, energy-based techniques (e.g., tissue “fusion” or tissue “welding”) exhibit promise for the closure, repair and functional recovery ...


Zonal Articular Cartilage Possesses Complex Mechanical Behavior Spanning Multiple Length Scales: Dependence On Chemical Heterogeneity, Anisotropy, And Microstructure, Joseph Anders Wahlquist Jan 2017

Zonal Articular Cartilage Possesses Complex Mechanical Behavior Spanning Multiple Length Scales: Dependence On Chemical Heterogeneity, Anisotropy, And Microstructure, Joseph Anders Wahlquist

Mechanical Engineering Graduate Theses & Dissertations

This work focused on characterizing the mechanical behavior of biological material in physiologically relevant conditions and at sub millimeter length scales. Elucidating the time, length scale, and directionally dependent mechanical behavior of cartilage and other biological materials is critical to adequately recapitulate native mechanosensory cues for cells, create computational models that mimic native tissue behavior, and assess disease progression. This work focused on three broad aspects of characterizing the mechanical behavior of articular cartilage. First, we sought to reveal the causes of time-dependent deformation and variation of mechanical properties with distance from the articular surface. Second, we investigated size dependence ...


Zonal Articular Cartilage Possesses Complex Mechanical Behavior Spanning Multiple Length Scales: Dependence On Chemical Heterogeneity, Anisotropy, And Microstructure, Joseph Anders Wahlquist Jan 2017

Zonal Articular Cartilage Possesses Complex Mechanical Behavior Spanning Multiple Length Scales: Dependence On Chemical Heterogeneity, Anisotropy, And Microstructure, Joseph Anders Wahlquist

Mechanical Engineering Graduate Theses & Dissertations

This work focused on characterizing the mechanical behavior of biological material in physiologically relevant conditions and at sub millimeter length scales. Elucidating the time, length scale, and directionally dependent mechanical behavior of cartilage and other biological materials is critical to adequately recapitulate native mechanosensory cues for cells, create computational models that mimic native tissue behavior, and assess disease progression. This work focused on three broad aspects of characterizing the mechanical behavior of articular cartilage. First, we sought to reveal the causes of time-dependent deformation and variation of mechanical properties with distance from the articular surface. Second, we investigated size dependence ...


Osteochondral Tissue Modeling Of Damage, Poroelastcity, And Remodeling In Osteoarthritis, Michael Eric Stender Jan 2015

Osteochondral Tissue Modeling Of Damage, Poroelastcity, And Remodeling In Osteoarthritis, Michael Eric Stender

Mechanical Engineering Graduate Theses & Dissertations

Arthritis is the most costly disability in the United States annually incurring billions of dollars in treatment costs and lost wages. Osteoarthritis, a classification of arthritis, affects articulating synovial joints (e.g., hip, knee, shoulder) and results in moderate to severe pain. In extreme cases, osteoarthritis causes loss of joint mobility. Presently, there is not a clear understanding of how osteoarthritis initiates, propagates, and ultimately degrades the mechanics of healthy synovial joints. This doctoral work uses computational modeling techniques and finite element analysis to elucidate the initiation and evolution of osteoarthritis with the ultimate goal of contributing to improved clinical ...


Experimental Analysis And Modeling Of Robot-Tissue Contact Mechanics For In Vivo Mobility, Levin John Sliker Jan 2015

Experimental Analysis And Modeling Of Robot-Tissue Contact Mechanics For In Vivo Mobility, Levin John Sliker

Mechanical Engineering Graduate Theses & Dissertations

Robotic mobility within the gastrointestinal (GI) tract is an intriguing concept, which has received wide attention from within the research community over the past ten years. Capsule endoscopes (CEs) exist commercially, but lack an active mobility system, rendering them as passive devices. These passive devices are only capable of observational procedures, and are limited by the passive speed (dependent on intestinal peristalsis), inability to control orientation, and vulnerability to retention, requiring surgical removal in severe cases. Additionally, passive capsules take photos throughout their journey, resulting in a compilation of thousands of images, which can take the attending physician hours to ...


On The Generalization Of Decision-Making Preferences In Movement Under Risk, Megan Kathleen O'Brien Jan 2014

On The Generalization Of Decision-Making Preferences In Movement Under Risk, Megan Kathleen O'Brien

Mechanical Engineering Graduate Theses & Dissertations

Nearly every aspect of our behavior is framed by risk, and people can respond to risk very differently. Some individuals readily confront highly variable situations in order to obtain large rewards (risk-seeking behavior), while others prefer more certain situations even if it means obtaining smaller rewards (risk-averse behavior).

At present, the role that risk plays in movement decisions is poorly understood. This dissertation investigates human movement decisions under risk, exploring the rationality of movement behavior in risky constructs and whether sensitivity to risk generalizes across movements. In the first study, I compared risk-sensitivity between two continuous motor tasks (arm-reaching and ...


Optically Active Plasmonic Microbubbles, Jacob Dove Jan 2014

Optically Active Plasmonic Microbubbles, Jacob Dove

Mechanical Engineering Graduate Theses & Dissertations

Contrast agents are used across a variety of medical imaging modalities for improved visualization of structures in the body. Microbubbles, for example, efficiently scatter ultrasound thereby providing enhanced ultrasonic imaging of the vasculature. Plasmonic nanoparticles, on the other hand, are efficient optical absorbers and can provide improvements in optical and photoacoustic imaging.

The focus of this thesis is on the development of novel contrast agents capable of enhancing both ultrasound and photoacoustic imaging modalities. The first agent is constructed by templating nanoparticles onto a lipid-encapsulated microbubble with a perfluorocarbon gas core. Using an avidin-biotin conjugation scheme, control over the nanoparticle ...


Ultrasound Assisted Cavitation Around Pulsed Laser Illuminated Nanoparticles, Hengyi Ju Jan 2013

Ultrasound Assisted Cavitation Around Pulsed Laser Illuminated Nanoparticles, Hengyi Ju

Mechanical Engineering Graduate Theses & Dissertations

The laser generation of vapor bubbles around plasmonic nanoparticles can be enhanced through the application of an ultrasound field; a technique referred to as photoacoustic cavitation. The combination of light and sound allows for bubble formation at lower laser fluence and peak negative ultrasound pressure than can be achieved using either modality alone. The growth and collapse of these bubbles leads to local mechanical disruption and acoustic emission, and can potentially be used to induce and monitor tissue therapy. The objective of this thesis is to understand the physics of nanoparticle-mediated photoacoustic cavitation, develop approaches to minimize the cavitation threshold ...


The Effects Of Matrix Elasticity, Composition, And Exogenous Growth Factors On The Vascular Differentiation Of Mesenchymal Stem Cells, Kathryn Anne Wingate Jan 2013

The Effects Of Matrix Elasticity, Composition, And Exogenous Growth Factors On The Vascular Differentiation Of Mesenchymal Stem Cells, Kathryn Anne Wingate

Mechanical Engineering Graduate Theses & Dissertations

Cardiovascular diseases are the leading cause of death in the western world. Regeneration of functional vascular tissue remains a critical barrier to successful treatment of these diseases. Attempts to produce functional vascular tissue with autogenous vascular cells have limited success due to the need for invasive surgery. Mesenchymal stem cells (MSCs) are a powerful cellular alternative for vascular regeneration as they are easily obtainable, multipotent, and thrombo-resistant. Currently, the mechanisms that drive MSC differentiation to healthy or diseased vascular phenotypes are not well understood. There is a critical need to define the factors in the cellular microenvironment that guide MSC ...


Bone Morphology And Mechanical Properties In Murine Models Of Chronic Kidney Disease, Andrew C. Cureton Jan 2013

Bone Morphology And Mechanical Properties In Murine Models Of Chronic Kidney Disease, Andrew C. Cureton

Mechanical Engineering Graduate Theses & Dissertations

The aim of this thesis is to investigate the changes in the bone tissue of mice that occur as a result of Chronic Kidney Disease (CKD). Due to the disruptions in mineral homeostasis and metabolism that result from loss of renal function, individuals with CKD are at a higher risk of bone fracture. In order to study the relationship between CKD and bone responses two surgical models of CKD are used herein: uninephrectomy (UNx) and 5/6 nephrectomy (5/6Nx). In general, surgically induced CKD was accompanied with a decrease in bone quality as measured by &muCT morphological analysis, mechanical ...


Design, Development, And Verification Of An Automated Pain Measurement Device, Morgan L. Hill Jan 2013

Design, Development, And Verification Of An Automated Pain Measurement Device, Morgan L. Hill

Mechanical Engineering Graduate Theses & Dissertations

The focus of this study is the redesign, development, fabrication, and initial evaluation of an automated pain measurement device. The redesign will focus on improving the original Computer Controlled Pressure Algometer, designed by Zimkowski in 2010. Pain measurement is very difficult to accurately accomplish, and current methods are limited to subjective techniques such as pain rating scales and handheld algometry. These subjective methods of pain measurement have many shortcomings that render them inadequate at reliably assessing an individual's pain. Large variability has been shown with these testing methods, which can be prone to error due to test administrator, environmental ...


Migrating Motor Complex Force Sensor: Design, Fabrication, And Clinical In Vivo Measurements, Matthew Michael Francisco Jan 2013

Migrating Motor Complex Force Sensor: Design, Fabrication, And Clinical In Vivo Measurements, Matthew Michael Francisco

Mechanical Engineering Graduate Theses & Dissertations

In a continued effort to explore the human digestive tract for diagnostic and therapeutic purposes in a minimally invasive fashion, researchers are developing a new type of medical device: the robotic capsule endoscope (RCE). This small, untethered instrument is actively controlled by the physician and combines the functionality of traditional, flexible endoscopy with the versatility of a swallowable device. The narrow, convoluted geometry and active peristaltic forces within the small intestine represent the most challenging environment within the human gastrointestinal (GI) tract for a RCE to operate. A critical design parameter is the active peristaltic forces generated by the migrating ...


Thermal Tissue Fusion Of Arteries: Methods, Mechanisms, & Mechanics, James David Cezo Jan 2013

Thermal Tissue Fusion Of Arteries: Methods, Mechanisms, & Mechanics, James David Cezo

Mechanical Engineering Graduate Theses & Dissertations

Tissue fusion is a method of joining biological tissues using heat and pressure. Tissue fusion has been used effectively for the ligation of blood vessels during surgery, which is performed by clamping the blood vessel closed and then applying heat to the tissue. During tissue fusion, the structural proteins in the tissue denature, water is vaporized, and a bond is formed between the tissues. The mechanics and mechanisms of the tissue fusion bond are still unknown and to this end, experiments were developed to elucidate the crucial parameters necessary to fuse tissue and measure the mechanical response of the bond ...


Proteomic Characterization Of The Chorion, Jennifer Downing Scholler Jan 2012

Proteomic Characterization Of The Chorion, Jennifer Downing Scholler

Mechanical Engineering Graduate Theses & Dissertations

Fetal membranes were collected from term, vaginal deliveries with no known pregnancy-related complications. Samples were collected from spontaneously rupturing (SROM; n=5) and artificially rupturing (AROM; n=2) membranes. For each membrane, samples were taken proximal to and distal from the rupture initiation site. Mass spectrometry identified several proteins involved in assembly, wound response and immune response as differentially expressed between the placental and rupture regions. In particular, basement membrane proteins including fibrillin and laminin were observed exclusively in the artificially rupturing samples, and fibrinogen was found in the rupture region in AROM but not SROM samples. Talin and vinculin ...


The Design And Evaluation Of A Pediatric Cardiothoracic Camera System For Identification And Repair Of Ventricular Septal Defects, Keir D. Hart Jan 2011

The Design And Evaluation Of A Pediatric Cardiothoracic Camera System For Identification And Repair Of Ventricular Septal Defects, Keir D. Hart

Mechanical Engineering Graduate Theses & Dissertations

Current detection of Ventricular Septal Defects (VSD) in pediatric patients can be difficult for hard to reach anatomy, such as apical defects, or for multiple VSDs. Existing technology such as Magnetic Resonance Imaging (MRI), catheterization, and echocardiography can be expensive, dangerous, or simply does not provide adequate images of these holes in the septal wall. Similarly, state of the art treatment practices have definitive limits in capability. Cardiac Transcatheterization and subsequent implantation of an occlusion device may not succeed as the occluder may be too close to heart valves or in relation to each other in the case of multiple ...


Design And Experimental Evaluation Of A Single Incision Laparoscopic Surgery Camera System For Minimally Invasive Surgery, Zachary Mills Jan 2011

Design And Experimental Evaluation Of A Single Incision Laparoscopic Surgery Camera System For Minimally Invasive Surgery, Zachary Mills

Mechanical Engineering Graduate Theses & Dissertations

Single incision laparoscopic surgery (SILS) offers many benefits over traditional open surgery. SILS is a type of minimally invasive surgery (MIS) which aims to reduce patient trauma by decreasing the number of incisions required for a surgical operation down to one located at the belly button (umbilicus). This offers patient benefits including reduced trauma, risk of infection, post-operative pain, scaring, and a shorter recovery time. SILS remains surgically challenging due to limited surgical tool motion and positioning of the traditional laparoscope through the SILS entry incision.

The SILS-specific camera systems presented here integrates all the features of a laparoscopic vision ...


Design And Development Of Multilayer Vascular Graft, Krishna Madhavan Jan 2011

Design And Development Of Multilayer Vascular Graft, Krishna Madhavan

Mechanical Engineering Graduate Theses & Dissertations

Vascular graft is a widely-used medical device for the treatment of vascular diseases such as atherosclerosis and aneurysm as well as for the use of vascular access and pediatric shunt, which are major causes of mortality and morbidity in this world. Dysfunction of vascular grafts often occurs, particularly for grafts with diameter less than 6mm, and is associated with the design of graft materials. Mechanical strength, compliance, permeability, endothelialization and availability are issues of most concern for vascular graft materials. To address these issues, we have designed a biodegradable, compliant graft made of hybrid multilayer by combining an intimal equivalent ...


Nanoindentation Of Bio- And Geo-Mineralized Composites: Contribution Of Microstructure And Composition, Sara E. Campbell Apr 2010

Nanoindentation Of Bio- And Geo-Mineralized Composites: Contribution Of Microstructure And Composition, Sara E. Campbell

Mechanical Engineering Graduate Theses & Dissertations

Bio-mineralized composite tissues, such as bone and teeth, are heterogeneous in both mineral composition and crystallinity. These tissues are altered throughout life by aging, wear, microfracture, and various disease states (e.g., osteoporosis), and are then further altered geologically after death by fossilization to create geo-mineralized tissues. Bone and enamel exhibit a wide range of mechanical responses at nanometer-length scales, where large-scale porosity and macro-structural variation are not factors. Some variability seen in mineralized tissues can be attributed to the amount of mineral; where a general increase in mechanical properties occurs with increasing mineral volume fraction. However, a large range ...


Biaxial Mechanical Characterization And Microstructure-Driven Modeling Of Elastic Pulmonary Artery Walls Of Large Mammals Under Hypertensive Conditions, Philip Hsien-Lan Kao Jan 2010

Biaxial Mechanical Characterization And Microstructure-Driven Modeling Of Elastic Pulmonary Artery Walls Of Large Mammals Under Hypertensive Conditions, Philip Hsien-Lan Kao

Mechanical Engineering Graduate Theses & Dissertations

Pulmonary Hypertension (PH) is a disease of the pulmonary vasculature which causes right heart failure. It is known that PH causes significant remodeling of the pulmonary arterial vasculature, but the effects of this remodeling are not well-understood. In addition, there is a dearth of research in large mammals for PH. Modeling of the arteries is also important in the simulation of deformation due to blood flow. Current models either do not reflect the microstructure, or are too complex for clinical use. This work presents mechanical characterization and analysis of the artery wall, in addition to a constitutive model driven by ...