Biomedical Engineering and Bioengineering Commons^™

Spatial And Temporal Deformation Pattern Of The Brain From Blunt Trauma, Abdus Ali

Theses

It is widely accepted that under extreme loadings the soft tissue of the brain will deform inside the skull, creating large amounts of both stress and strain on the tissue. This can result in a focal injury, or in the case of acceleration and deceleration, diffuse injuries. Any attempt at understanding the underlying mechanisms and effects of TBI, have to start by focusing on what is actually occurring within the brain. The objective of this experiment is to record differences in the spatial and temporal patterns of deformation within the brain during blunt trauma when changing impact parameters. A linear …

Interaction Of Voluntary Activity And Functional Electrical Stimulation In The Upper Extremity As A Method For Short-Term Alteration Of Corticospinal Excitability And Force Control, Katherine Maia Gerton

Theses

Repetitive movement training (RMT) is a well-established method for rehabilitating functional movement. However, many stroke survivors are not able to participate in RMT for the necessary duration to produce results due to rapid muscle fatigue or inability to perform the desired movement at all. Often, functional electrical stimulation (FES) is applied passively, as a rehabilitative therapy, to stroke subjects who are unable to participate in RMT. The effects of voluntary contraction and FES are not well understood for the upper extremity following a stroke. This experiment was designed to elucidate the mechanisms of functional and neurophysiological changes associated with combining …

Subject And Group Level Changes And Comparison In Functional Connectivity Under Low Vs. High Cognitively Demanding Naturalistic Viewing Conditions Using Fmri, Rakibul Hafiz

Theses

Resting State fMRI is used extensively for analysing brain regions. fMRI is also used to determine task induced activations from cerebral networks. This study involves both rest and task activation data and implements statistical methods applied on Blood Oxygenation Level Dependent (BOLD) signals. The conventional task based designs are very specific and may not reflect day to day activities. The two task conditions in this study are watching a movie called INSCAPE with low cognitive load and segments of contextual Hollywood movies under continuous and natural conditions.

The aim is to investigate individual and group level Functional Connectivity changes between …

The Use Of Audio Stimulation To Affect Sensorimotor Learning, Gregory Nicholas Ranky

Dissertations

Sensorimotor learning for the hand and fingers can be conducted using both hardware and software components, but the training regime is also important. Using repetitive sequence tapping allows measurement of defined metrics in a controlled, safe environment, and therefore statistical indications for subject improvement.

The process of entrainment, when a subject’s own movements synchronize to an external signal, has been tested in prior studies for memorization and recognition, but has not been investigated for correlation with sensorimotor learning.

This is tested with selected custom isochronic audio tones, combined with sequential finger tapping on a standard computer keyboard.

Whilst there were …

A Novel Approach To Increase Upper Extremity Active Range Of Motion For Individuals With Duchenne Muscular Dystrophy Using Admittance Control, Madeline Catherine Corrigan

Dissertations

Duchenne muscular dystrophy (DMD), a neuromuscular disease with a prevalence of 1 in 3,500-5,000 male births, results in progressive muscle weakness causing loss of independence and imposing the demands of costly and intrusive assistive support and personal care for daily living tasks. Upper extremity function begins to decline while ambulation is still possible and gradually progresses with time, playing a prominent role in loss of independence. Importantly, upper extremity functional limitations exist despite residual muscle strength that is insufficient to lift the arms against gravity. Presently, there exist a number of commercially available assistive devices aimed at augmenting upper extremity …

Profiling The Neurovascular Cell Interactions In Alcohol Exposure And Hiv-1 Infection, Agnieszka Agas

Theses

Alcohol use is known to exacerbate the progression of human immunodeficiency virus associated acquired immunodeficiency syndrome or HIV/AIDS in the brain, known as the NeuroAIDS. The mechanisms of this accelerated progression are still poorly understood. The purpose of my thesis is to review the parameters contributing to the co-morbid effects of alcohol in the progression of NeuroAIDS. The first aim will evaluate the exacerbating effects of alcohol on HIV-1 transmission, infection, and the role of metabolic energy imbalance during NeuroAIDS progression, which will enable me to formulate the possible mechanism for NeuroAIDS progression. The second aim will help me establish …

Experimental Study Of Bubble Rupture During Shock-Fluid Interaction, Subhalakshmi Chandrasekaran

Theses

Head injuries are associated with exposure to high energy explosive detonation. There are four distinct types of blast induced neurotrauma (BINT): 1) these caused by supersonic shock waves propagating in the atmosphere (primary), 2) high velocity impact of shrapnel and debris (secondary) 3) acceleration and deceleration of the body and collision with the solid objects in the field (tertiary) and 4) exposure to high temperature and toxic gases (quaternary). One of the mechanisms implicated in non-impact primary blast-induced traumatic brain injury (bTBI) is cavitation. It is hypothesized that cavitation can occur in the cerebrospinal fluid (CSF) layer, brain interstitial fluid, …

Measurement Of Finger Coordination During A Motor Learning Task, Robert Ebel

Theses

The focus of this study is to observe the changes in whole hand grasp strategy, in healthy subjects, over time in a series of isometric force control learning tasks. During a series of trials with real-time visual feedback of the five finger forces, subjects adapted their grasp strategy in order to reach the target in a time efficient manner. In early trials, it is very evident that subjects focus on controlling the force output of one finger at a time until they reach the goal. As the block of trials progresses, subjects alter their strategy to a more coordinated movement …

Assessment Of A Hand Exoskeleton On Proximal And Distal Training In Virtual Environments For Robot Mediated Upper Extremity Rehabilitation, Kevin Abbruzzese

Dissertations

Stroke is the leading cause of disability in the United States with approximately 800,000 cases per year. This cerebral vascular accident results in neurological impairments that reduce limb function and limit the daily independence of the individual. Evidence suggests that therapeutic interventions with repetitive motor training can aid in functional recovery of the paretic limb. Robotic rehabilitation may present an exercise intervention that can improve training and induce motor plasticity in individuals with stroke. An active (motorized) hand exoskeleton that provides support for wrist flexion/extension, abduction/adduction, pronation/supination, and finger pinch is integrated with a pre-existing 3-Degree of Freedom (DOF) haptic …

Denoising Techniques Reveal Neural Correlates Of Modulation Masking Release In Auditory Cortex, Sahil Chaubal

Theses

Hearing aids allow hearing impaired (HI) individuals to regain auditory perception in quiet settings. However, despite advances in hearing aid technology, HI individuals do not perform as well in situations with background sound as normally hearing (NH) listeners. An extensive literature demonstrates that when comparing tone detection performance in background noise, NH listeners have better thresholds when that noise is temporally modulated as compared to temporally unmodulated. However, this perceptual benefit, called Modulation Masking Release (MMR), is much reduced in HI listeners, and this is thought to be a reason for why HI listeners struggle in the presence of background …

Fabrication Of 3d Hydrogel-Based Microscale Tissue Analog Chip With Integrated Optofluidics, Venkatakrishnan Rengarajan

Dissertations

Lab-on-a-chip (LOC) is a device that integrates one or more laboratory functions in a single chip with dimensions ranging from a micrometer to a few millimeters. On-chip optofluidics, which combines microfluidics and tunable micro-optical components, is crucial for bio-sensing applications. However, recently reported optofluidic devices have only two-dimensional (2D) dielectric or metallic regions for sensing cellular activity, which fail to mimic the three-dimensional (3D) in vivo microenvironment of cells.

In this research, a 3D hydrogel-based micro-scale-tissue-analog-chip (µTAC) is fabricated with an integrated optofluidic design for biomedical applications. These 3D hydrogels act as a scaffold for the cellular studies and as …

Biomimetic And Vascularized 3-D Liver Cancer Model, Derek Yip

Dissertations

Anti-angiogenic drugs have failed to show significant extended mortality, except when co-administered with chemotherapy drugs in clinical trials. This should be predicted by in vitro models, and yet 2D in vitro models of liver cancer co-administered with these two types of drugs show increased cell viability, contradicting clinical trials. In vitro models should mimic clinical trials in order to accurately predict drug outcomes. 2D in vitro models fail because they lack features of the cancer environment such as presence of stromal cells and a vasculature.

In order to achieve a biomimetic and vascularized in vitro model that would better recapitulate …

A Multimodal Investigation In Eye Movements, Raj Jaswal

Dissertations

While functional magnetic resonance imaging (fMRI) has identified which regions of interest (ROIs) are functionally active during a vergence movement (inward or outward eye rotation), task-modulated coactivation between ROIs is less understood. This study tests the following hypotheses: (1) significant task-modulated coactivation would be observed between the frontal eye fields (FEFs), the posterior parietal cortex (PPC), and the cerebellar vermis (CV); (2) significantly more functional activity and task-modulated coactivation would be observed in binocularly normal controls (BNCs) compared with convergence insufficiency (CI) subjects; and (3) after vergence training, the functional activity and task-modulated coactivation would increase in CIs compared with …

A Novel Approach To User Controlled Ambulation Of Lower Extremity Exoskeletons Using Admittance Control Paradigm, Kiran Kartika Karunakaran

Dissertations

The robotic lower extremity exoskeletons address the ambulatory problems confronting individuals with paraplegia. Paraplegia due to spinal cord injury (SCI) can cause motor deficit to the lower extremities leading to inability to walk. Though wheelchairs provide mobility to the user, they do not provide support to all activities of everyday living to individuals with paraplegia.

Current research is addressing the issue of ambulation through the use of wearable exoskeletons that are pre-programmed. There are currently four exoskeletons in the U.S. market: Ekso, Rewalk, REX and Indego. All of the currently available exoskeletons have 2 active Degrees of Freedom (DOF) except …

Antibacterial Efficacy Of Nanometals In Conjunction With Electrical Stimulus, Syed A. Hussain

Theses

Hospital related infections generally result from the combined effect of preexisting bacteria on the patient and invasive devices. This demonstrates the significance in improving these medical devices to increase the quality of life of the patients that require them. This study will attempt to evaluate the antibacterial efficacy of nanocopper particles and an electrical stimulus for the usage in medical device development and the hospital environment.

For devices such as catheters, infections typically result from bacteria entering the body from the outside. This is accomplished by bacteria attaching themselves to the exterior of the device and producing biofilm which allows …

Continuum Mechanical Analysis Of Space And Time Dependent Deformation Pattern Of Brain With Blunt Injury, Chen Miao

Theses

Deformation of human brain due to acceleration impact has been widely accepted as the direct connection to the Trauma Brain Injury (TBI). However, the limitation of obtaining deformation data of TBI is a major obstacle to understanding TBI mechanism. This experiment mainly focuses on developing a method to measure deformation pattern of brain with blunt injury. First of all, displacement data of markers on sagittal plane of an injury head model was collected using 3D reconstruction software after an impact test. Second, the displacement data was used to calculate 2D Lagrangian strain tensor and the principal strain. The temporal and …

An Electromechanical System For Characterization Of Piezoelectric Materials, Ahmet Sait Asan

Theses

Piezoelectric materials have been used in medical applications for a long time due to their unique characteristics, which is to respond to mechanical stimulation by producing an electrical current and vice versa. They perform a pivotal role in medical applications both for diagnostic and therapeutic purposes. In this regard, characterizing the piezoelectric properties of these materials is crucial for their usage. In this particular study, an electromechanical system for measurement of piezoelectric output signals is designed and tested. The project is motivated by the question: can the piezoelectric properties be characterized by applying different mechanical stimulation waveforms and frequencies. Two …

Response Of Stretch-Injured Schwann Cells, Stephanie Iring

Theses

Axon fibers are covered by myelin sheath. After axonal damage, demyelination follows with the production of debris. In the Central Nervous System many studies have been performed to observe and analyze stretch injured axons, but very little has been done to study the white matter axonal tracts, oligodendrocytes. Schwann cells can help take a first look into stretch injured glia cells from the Peripheral nervous system. In order to observe changes in Schwann Cells a stretch injury device is used to produce the effects of severe and moderate injuries. Schwann Cells are stretch injured in both their undifferentiated and differentiated …

Effect Of Melt Method On Thoracolumbar Connective Tissue, Faria Sanjana

Theses

Approximately, 31 million adults in the United States suffer from low back pain (LBP). Altered connective tissue structure has been identified in adults with chronic LBP. Numerous novel treatments are being developed targeting the connective tissue and nervous system to relieve people from LBP. One such self-care treatment is the MELT method. The objective of this study was to determine whether thickness of thoracolumbar connective tissue and other biomechanical and viscoelastic properties of myofascial tissue in the low back region change in subjects with chronic LBP as a result of MELT.

Using ultrasound imaging and an algorithm developed in MATLAB, …

Hand Control Of Bipedal Balance In Quiet Standing: Implementations For Lower Extremity Exoskeleton, Ala’A Al-Rashdan

Dissertations

Maintaining stable posture is important for humans, even though it is challenging because of our bipedal structure. One of the main balance related disorders is paraplegia due to spinal cord injury. People with a complete spinal cord injury have motor and sensory impairment that greatly reduces the ability to move their lower extremities. In recent years, lower extremity exoskeletons that apply torques generated by motors to the joints of the person have helped to them stand and walk.

This research is a part of an extended project to build a new exoskeleton for use by individuals with paraplegia due to …

Plasticity Of The Cortical Representation Of Finger Extensors Induced By Paired Associative Stimulation, Ian Anthony Gerard Lafond

Dissertations

This dissertation first explored associative plasticity of the human motor cortical representation with the use of noninvasive transcranial magnetic stimulation (TMS) paired with peripheral electrical stimulation. Paired Associative Stimulation (PAS) has grown in popularity because of its potential clinical applications. PAS techniques are used in combination with electromyography (EMG) measurements to study cortical excitability and features of hand movement. This work focuses on a cohesive approach to answer central questions about: the ideal mechanism to facilitate cortical plasticity via PAS, the interaction between the behavior performed and type of stimulation delivered to the targeted cortical network and the effects of …

Investigating Neural Mechanisms Of Hand Movements In Virtual Reality, Chuang Mu

Theses

Mirror visual feedback (MVF), a technique by which movement of one limb is perceived as movement of the contralateral limb, has the capacity to relieve phantom limb pain or promote motor recovery of the upper limbs after stroke (Ramachandran et al., 1995). Functional MRI studies have demonstrated activation of the motor areas in the hemisphere ipsilateral to the moving hand in response to MVF. However, the neural mechanisms of MVF are still unclear. This Electroencephalography (EEG) study was designed to investigate the timing of neural responses to MVF presented in virtual reality. 16 right-handed, neurologically healthy subjects participated in a …

A Study Of Kinematics And Kinetics In Time-Constrained Arm Movements, Oyindamola Owoeye

Theses

Several studies such as the equilibrium point hypothesis (EPH) purport that the motor signals that descend from the brain instead of encoding muscle torques, influence an existing relationship between muscle torque and body configuration.

In the present study, the possibility of torque depending explicitly on position was tested using a task in which subjects (N=5) moved a simulated weightless frictionless mass through a small (<8 degree) elbow extension in order to move a cursor on a screen to a target location. Each subject completed 720 trials. On ~10% of trials the simulated mass was increased unknown to the subject. The relationship between the cursor’s position and the torque applied to the system was held constant even when the simulated mass was increased. Thus, any change in torque produced was neither due the subjects’ perception of the mass nor due to their perception of the cursor. The time at which the subjects torque changed direction was seen to be significantly different (p<0.005) during trials which the mass changed. This change in torque is concluded to be position-dependent. However the possibility of this being a merely mechanical effect could not be ruled out by due to poor EMG collection.

A post-hoc analysis of different position-dependent motor control models, was done. Particularly, an exponential spring model, a linear spring model, and a linear spring with relative damping model were each tested to see how well …

Realization Of Dynamixel Servo Plant Parameters To Improve Admittance Control For A Compliant Human-Robot Interaction, Ahmad Zahid Rao

Theses

In theory, admittance control offers a very effective method of implementing smooth human-robot interaction. It allows the user’s applied force to control the movement of a powerful robot as if the robot were a small, passive mass. However, the real-world application of admittance control faces limitation posed by the dynamics of servo motors, the accuracy of the force sensors, and the computation speed of processors.

This research investigates the limitations on achieving compliant passive behavior when using state-of-the-art actuators, sensors and processors. The work involves characterizing the dynamic behavior of the servo motors, development of improved differential equations representing admittance …

Comparison Of Muscle Synergies Elicited From Transcranial Meganetic Stimulation (Tms) And Voluntary Movements, Yifei Wei

Theses

A key question in motor control is the redundancy of musculoskeletal elements involved. This problem refers to as the degree of freedom problem. The Muscle Synergy Hypothesis is one of the hypotheses that aim to resolve the problem which defines that a muscle synergy is a combination of a small set of muscles activated at different levels, serving as a building block that constructs motor behaviors. A recent study (Overduin et al. 2012) demonstrated that muscle synergies decomposed by Nonnegative Matrix Factorization (NMF) from EMG patterns evoked by intra-cortical microsimulation (ICMS) in the monkey remarkably matched ones observed in naturalistic …

Rodent Testing Device Surrogate For Shockwave Blast Testing, Anthony C. Misistia

Theses

Many laboratories around the world are conduct shockwave blast injury tests on rodents to simulate blast traumatic brain injury (TBI). Each of these laboratories has different techniques for creating the shockwave blasts as well as positioning the rats. There is no device to determine whether or not the rodent animal models actually experiences a true blast wave in a given set up. This device was developed as a method for verifying rodents undergoing true shockwave blasts through biometrics, instrumentation and the basic biomechanical responses a rodent experiences during such tests. Since the goal of shockwave blast testing is to replicate …

High Frequency Field Potentials Of The Cerebellar Cortex, Jonathan David Groth

Dissertations

The cerebellum plays a crucial role in motor coordination along with basal ganglia and the motor areas of the cerebral cortex. Both somatosensory and the cerebro-cerebral pathways bring in massive amounts of neural information to the cerebellum. The output of the cerebellar cortex projects to various motor cortices as well as down to the spinal cord to make its contributions to the motor function.

The origin and function of the field potential oscillations in the cerebellum, especially in the high frequencies, have not been explored sufficiently. The primary objective of this study was to investigate the spatio-temporal characteristics of high …

Piezoelectric Scaffolds For Osteochondral Defect Repair, Sita Mahalakshmi Damaraju

Dissertations

Osteoarthritis is one of the most prevalent causes of disability affecting nearly 27 million Americans. Osteoarthritis is caused when extensive damage occurs to the articular cartilage later spreading to the underlying subchondral bone, resulting in osteochondral defects. The current clinical therapies aim at regenerating the hyaline cartilage, but instead fibrocartilage forms at the osteochondral defect site, which is inferior in structure and function and fails to integrate with the surrounding tissue. A biomimetic scaffold, which can provide cues similar to the native extracellular matrix, may facilitate osteochondral defect repair. Articular cartilage and bone extracellular matrix have been shown to produce …

Behavior Of Deformed Dermal Fibroblasts Seeded On A Silicon Membrane Under High Levels Of Strain, Laura Osorno

Theses

The main objective of this thesis is to understand, from a molecular perspective, the morphological and functional abnormalities of human dermal fibroblasts as a response to deformation produced by a normal force that can lead to the potential formation of stretch marks in pregnant women, adolescents, and people with Cushing's syndrome. The main function of dermal fibroblasts is to produce the essential fibrous components of the extracellular matrix (ECM) of the skin.

In order to study the mechanism of stretch mark formation, neonatal human dermal fibroblasts were seeded on a silicon membrane for controlled deformation. Upon reaching a confluence of …

Differentiation Of Mouse Embryonic Stem Cells Into Insulin-Producing Cells: Optimization To Enhance The Overall Differentiation Efficiency, Xiaotang Ma

Theses

Embryonic stem cells have the potential to differentiate into multiple cell types including insulin-producing cells (IPCs), which is becoming one of the promising cell sources for treating type 1 diabetes mellitus. However, in order to achieve functional stem cell-derived cells, it is important to generate more mature IPCs and to keep long-term viability post differentiation process. In this study, we varied several factors including different embryonic body culture conditions, digested cells seeding density and various coatings required for differentiation to optimize a previously established protocol to enhance the overall differentiation efficiency. Moreover, a three-dimensional in vitro collagen tissue culture system …