Biomedical Engineering and Bioengineering Commons^™

The Influence Of Flow Mechanotransduction On Endothelial Cells In The Lymphatic Valve Sinus, Joshua Daniel Hall

Doctoral Dissertations

Fluid flow in the cardiovascular and lymphatic systems influences the phenotype of endothelial cells that line the interior to the vessel via mechanotransduction. Geometric features in a vessel such as curvature, bifurcation, and valves promote heterogeneous fluid flow profiles, inducing a heterogeneous endothelial phenotype within a vessel region. Certain flow conditions are associated with vascular dysfunction, and diseases such as atherosclerosis preferentially develop in areas of flow disturbance. Lymphatic vessels are highly analogous to blood vessels, although lymphatic flow characteristics and its effect on lymphatic endothelial cells (LECs) via mechanotransduction have been comparatively less examined. The most significant geometric features …

Characterizing Mechanical Regulation Of Bone Metastatic Breast Cancer Cells, Boyuan Liu

Doctoral Dissertations

Breast cancer most frequently metastasizes to the skeleton. Bone metastatic cancer is incurable and induces wide-spread bone osteolysis, resulting in significant patient morbidity and mortality. Mechanical stimuli in the skeleton are an important microenvironmental parameter that modulates tumor formation, osteolysis, and tumor cell-bone cell signaling, but which mechanical signals are the most beneficial and the corresponding molecular mechanisms are unknown. This work focused on bone matrix deformation and interstitial fluid flow based on their well-known roles in bone remodeling and in primary breast cancer. The goal of our research was to establish a platform that could define the relationship between …

Visuomotor Adaptation During Asymmetric Walking, Charles Napoli

Masters Theses

Necessary for effective ambulation, head stability affords optimal conditions for the perception of visual information during dynamic tasks. This maintenance of head-in-space equilibrium is achieved, in part, by the attenuation of the high frequency impact shock resulting from ground contact. While a great deal of experimentation has been done on the matter during steady state locomotion, little is known about how head stability or dynamic visual acuity is maintained during asymmetric walking.

In this study, fifteen participants were instructed to walk on a split-belt treadmill for ten minutes while verbally reporting the orientation of a randomized Landolt-C optotype that was …

A Generalized Method For Predictive Simulation-Based Lower Limb Prosthesis Design, Mark Price

Doctoral Dissertations

Lower limb prostheses are designed to replace the functions and form of the missing biological anatomy. These functions are hypothesized to improve user outcome measures which are negatively affected by receiving an amputation – such as metabolic cost of transport, preferred walking speed, and perceived discomfort during walking. However, the effect of these design functions on the targeted outcome measures is highly variable, suggesting that these relationships are not fully understood. Biomechanics simulation and modeling tools are increasingly capable of analyzing the effects of a design on the resulting user gait. In this work, prothesis-aided gait is optimized in simulation …

Design And Biomechanical Evaluation Of A Clutch-Based Energy Storage And Release Assistive Knee Brace, Ericber Jimenez Francisco

Doctoral Dissertations

Knee osteoarthritis (OA) is a serious degenerative disease affecting over 240 million people around the world. The most disabling symptoms are joint pain, joint stiffness, and reduction in joint functionality. Medial compartment knee OA is the most common case of unicompartmental knee OA, and pain and progression have been associated with tibiofemoral alignment in early to moderate knee OA patients, mainly due to its association with knee loading as measured by knee adduction moment (KAM) and tibiofemoral contact forces (KCF). Valgization knee braces have been developed to correct the malalignment at the tibiofemoral joint, but they have no direct effect …

Predictive Simulation Of Human Movement And Applications To Assistive Device Design And Control, Vinh Nguyen

Doctoral Dissertations

Predictive simulation based on dynamic optimization using musculoskeletal models is a powerful approach for studying biomechanics of human gait. Predictive simulation can be used for a variety of applications from designing assistive devices to testing theories of motor controls. However, one of the challenges in formulating the predictive dynamic optimization problem is that the cost function, which represents the underlying goal of the walking task (e.g., minimal energy consumption) is generally unknown and is assumed a priori. While different studies used different cost functions, the qualities of the gaits with those cost functions were often not provided. Therefore, this dissertation …

Supporting Engineering Design Of Additively Manufactured Medical Devices With Knowledge Management Through Ontologies, Thomas Hagedorn

Doctoral Dissertations

Medical environments pose a substantial challenge for engineering designers. They combine significant knowledge demands with large investment for new product development and severe consequences in the case of design failure. Engineering designers must contend with an often-chaotic environment to which they have limited access and familiarity, a user base that is difficult to engage and highly diverse in many attributes, and a market structure that often pits stakeholders against one another. As medical care in general moves towards personalized models and surgical tools towards less invasive options emerging manufacturing technologies in additive manufacturing offer significant potential for the design of …

Effects Of Malformed Or Absent Valves To Lymphatic Fluid Transport And Lymphedema In Vivo In Mice, Akshay S. Pujari

Masters Theses

Lymph is primarily composed of fluid and proteins from the blood circulatory system that drain into the space surrounding cells, interstitial space. From the interstitial space, the fluid enters and circulates in the lymphatic system until it is delivered into the venous system. In contrast to the blood circulatory system, the lymphatic system lacks a central pumping organ dictating the predominant driving pressure and velocity of lymph. Transport of lymph via capillaries, pre-collecting and collecting lymphatic vessels relies on the synergy between pressure gradients, local tissue motion, valves and lymphatic vessel contractility. The direction of lymph transport is regulated by …

A Magnetic Resonance Compatible Knee Extension Ergometer, Youssef Jaber

Masters Theses

The product of this thesis aims to enable the study of the biochemical and physical dynamics of the lower limbs at high levels of muscle tension and fast contraction speeds. This is accomplished in part by a magnetic resonance (MR) compatible ergometer designed to apply a load as a torque of up to 420 Nm acting against knee extension at speeds as high as 4.7 rad/s. The system can also be adapted to apply the load as a force of up to 1200 N acting against full leg extension. The ergometer is designed to enable the use of magnetic resonance …

Multi-Classifier Fusion Strategy For Activity And Intent Recognition Of Torso Movements, Abhijit Kadrolkar

Doctoral Dissertations

As assistive, wearable robotic devices are being developed to physically assist their users, it has become crucial to develop safe, reliable methods to coordinate the device with the intentions and motions of the wearer. This dissertation investigates the recognition of user intent during flexion and extension of the human torso in the sagittal plane to be used for control of an assistive exoskeleton for the human torso. A multi-sensor intent recognition approach is developed that combines information from surface electromyogram (sEMG) signals from the user’s muscles and inertial sensors mounted on the user’s body. Intent recognition is implemented by following …

A Haptic Surface Robot Interface For Large-Format Touchscreen Displays, Mark Price

Masters Theses

This thesis presents the design for a novel haptic interface for large-format touchscreens. Techniques such as electrovibration, ultrasonic vibration, and external braked devices have been developed by other researchers to deliver haptic feedback to touchscreen users. However, these methods do not address the need for spatial constraints that only restrict user motion in the direction of the constraint. This technology gap contributes to the lack of haptic technology available for touchscreen-based upper-limb rehabilitation, despite the prevalent use of haptics in other forms of robotic rehabilitation. The goal of this thesis is to display kinesthetic haptic constraints to the touchscreen user …

A Continous Rotary Actuation Mechanism For A Powered Hip Exoskeleton, Matthew C. Ryder

Masters Theses

This thesis presents a new mechanical design for an exoskeleton actuator to power the sagittal plane motion in the human hip. The device uses a DC motor to drive a Scotch yoke mechanism and series elasticity to take advantage of the cyclic nature of human gait and to reduce the maximum power and control requirements of the exoskeleton. The Scotch yoke actuator creates a position-dependent transmission that varies between 4:1 and infinity, with the peak transmission ratio aligned to the peak torque periods of the human gait cycle. Simulation results show that both the peak and average motor torque can …

Design Of A Passive Exoskeleton Spine, Haohan Zhang

Masters Theses

In this thesis, a passive exoskeleton spine was designed and evaluated by a series of biomechanics simulations. The design objectives were to reduce the human operator’s back muscle efforts and the intervertebral reaction torques during a full range sagittal plane spine flexion/extension. The biomechanics simulations were performed using the OpenSim modeling environment. To manipulate the simulations, a full body musculoskeletal model was created based on the OpenSim gait2354 and “lumbar spine” models. To support flexion and extension of the torso a “push-pull” strategy was proposed by applying external pushing and pulling forces on different locations on the torso. The external …

Were Neandertal Humeri Adapted For Spear Thrusting Or Throwing? A Finite Element Study, Michael Anthony Berthaume

Masters Theses

An ongoing debate concerning Neandertal ecology is whether or not they utilized long range weaponry. The anteroposteriorly expanded cross-section of Neandertal humeri have led some to argue they thrusted their weapons, while the rounder cross-section of Late Upper Paleolithic modern human humeri suggests they threw their weapons. We test the hypothesis that Neandertal humeri were built to resist strains engendered by thrusting rather than throwing using finite element models of one Neandertal, one Early Upper Paleolithic (EUP) human and three recent human humeri, representing a range of cross-sectional shapes and sizes. Electromyography and kinematic data and articulated skeletons were used …

Tooth Cusp Radius Of Curvature As A Dietary Correlate In Primates, Michael Anthony Berthaume

Open Access Dissertations

Tooth cusp radius of curvature (RoC) has been hypothesized to play an important role in food item breakdown, but has remained largely unstudied due to difficulties in measuring and modeling RoC in multicusped teeth. We tested these hypotheses using a parametric model of a four cusped, maxillary, bunodont molar in conjunction with finite element analysis. When our data failed to support existing hypotheses, we put forth and tested the Complex Cusp Hypothesis which states that, during brittle food items breakdown, an optimally shaped molar would be maximizing stresses in the food item while minimizing stresses in the enamel. After gaining …