Engineering Commons^™

Individual Analysis Of T2*-Weighted Gradient Echo Imaging In Asymptomatic And Symptomatic Athletes, Xianglun Mao

Open Access Theses

Mild traumatic brain injury (mTBI), is a commonly occurred sports-related injury, especially in contact sports like football and soccer. Hemorrhage will appear as hypointense lesions on T₂ ^*-weighted images, resulting from mTBI. Thus, T ₂^*-weighted gradient echo pulse sequence can be used to generate magnitude susceptibility-weighted (SW) images, and to further detect negative intensity changes of different regions of interests (ROIs) inside human brains. Our goal was to investigate how the ROI-specific intensity changes in each individual sports athlete over a single competition season and to interrogate whether these changes are correlated with repetitive subconcussive or …

Measurement, Characterization, And Effects Of Head Impacts In Women's Soccer, Emily C. Mccuen

Open Access Theses

The potential for long term neurological deficits resulting from repetitive head trauma is a major concern for collision sport athletes. Research conducted on football played has found neurophysiologic changes in the absence of concussion in athletes as early as high school age. Given that female soccer players show the highest rate of concussion for female athletes and a higher rate of concussion than their male counterparts, it is important to characterize the types of impacts female soccer athletes receive and assess female soccer athletes for neurophysiologic changes due to these impacts. This work paired head impact sensors with functional MRI …

Magnetic Manipulation And Multimodal Imaging For Single Cell Direct Mechanosensing, Robert L. Wilson

Open Access Theses

The study of internal mechanics of single cells is paramount to understand mechanisms of mechanoregulation. External loading and cell-mediated force generation result in changes in cell shape, rheology, and the deformation of subcellular structures such as the nucleus. Moreover, alterations in the processes that regulate these responses have been further correlated to specific pathologies. Cellular deformation is often studied through application of forces in the environment of the cell, relying on strain and stress transfer through focal adhesions and the cytoskeletal system. However, the transfer of these external forces to internal mechanics can introduce uncertainties in the interpretation of subcellular …

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 …

Wireless Tools For Neuromodulation, Steven T Lee

Open Access Dissertations

Epilepsy is a spectrum of diseases characterized by recurrent seizures. It is estimated that 50 million individuals worldwide are affected and 30% of cases are medically refractory or drug resistant. Vagus nerve stimulation (VNS) and deep brain stimulation (DBS) are the only FDA approved device based therapies. Neither therapy offers complete seizure freedom in a majority of users. Novel methodologies are needed to better understand mechanisms and chronic nature of epilepsy. Most tools for neuromodulation in rodents are tethered. The few wireless devices use batteries or are inductively powered. The tether restricts movement, limits behavioral tests, and increases the risk …

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 …

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). …

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 …

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 …

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 …

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 …

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 …

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 …

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 …

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. …

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 …

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 …

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 …

The Effects Of Chronic Neural Implantation On Localized Vasculature, Andrew L. Ready

Open Access Theses

Prosthetic solutions currently available range from simple devices intended for aesthetics purposes to complex systems attempting to restore lost function and sensation; of these methods, none show more promise in restoration of normal function and life satisfaction than neural prosthetics. These devices directly interface with the nervous system in order to restore realistic function and feeling to the patient, potentially returning them to how their life once was. While in some cases patients requiring prosthetics can utilize peripheral nerves, those who suffer from injuries or disease which cause damage to the central nervous system can necessitate the usage of devices …

Particle Swarm Optimization Using Multiple Neighborhood Connectivity And Winner Take All Activation Applied To Biophysical Models Of Inferior Colliculus Neurons, Brandon S. Coventry

Open Access Theses

Age-related hearing loss is a prevalent neurological disorder, affecting as many as 63% of adults over the age of 70. The inability to hear and understand speech is a cause of much distress in aged individuals and is becoming a major public health concern as age-related hearing loss has also been correlated with other neurological disorders such as Alzheimer's dementia. The Inferior Colliculus (IC) is a major integrative auditory center, receiving excitatory and inhibitory inputs from several brainstem nuclei. This complex balance of excitation and inhibition gives rise to complex neural responses, which are measured in terms of firing rate …

Standardizing The Collection And Measurement Of Glucose In Exhaled Breath And Its Relationship To Blood Glucose Concentrations, Mark Hamilton

Open Access Theses

Blood glucose level control (glycemic control) is crucial in diabetes. Limitations in current commercially available monitoring devices include causing patient pain leading to poor blood glucose level management. The development of a non-invasive measurement system may lead to improved patient glycemic control, reducing unwanted side-effects and complications of poor blood glucose level maintenance.

This work explores the use of glucose within exhaled breath in attempt to establish an indirect method of blood glucose level measurement. Specifically, exhaled breath condensate (EBC) is examined. A breath condensing unit was designed to measure the temperature of the system, flow rate, volume of expired …

Robust, Degradable Peg-Based Collagen Hydrogels For Elastomeric Tissue Augmentation, Charles Wilbur Peak

Open Access Theses

Vocal folds are made of an elastomeric tissue and are essential to everyday life, allowing for communication. Approximately 28 million individuals have paralysis or scarring of the vocal folds mostly due to injury or systemic diseases. Symptoms may include voice hoarseness or fatigue. Healthy vocal folds consist of distinct layers of soft tissue. We are designing hydrogels with properties similar to these healthy tissues. The hydrogels are envisioned to be used as injectable and degradable tissue matrices that allow for repair and regeneration of the vocal folds. ^ We present the synthesis of a robust and degradable hydrogel system made …

Feasibility Of Pulsed Proton Induced Acoustics For 3d Dosimetry, Fahed M. Alsanea

Open Access Theses

Proton therapy has the potential to deposit its energy in tissue with high conformity to the tumor and significantly reduced integral dose to normal tissue compared to conventional radiation, such as x-rays. As a result, local control can be enhanced while reducing side-effects and secondary cancers. This is due to the way charged Particles deposit their energy or dose, where protons form a Bragg peak and establish a well-defined distal edge as a function of depth (range). To date, the dose delivered to a patient from proton therapy remains uncertain, in particular the positioning of the distal edge of the …

Developing A Hardware Platform For A Low-Power, Low-Cost, Size-Constrained Biomechanical Telemetry System, Aditya Balasubramanian

Open Access Theses

As sport-related traumatic brain injuries face increasing attention from the media and the general public, the need to be able to detect brain injury quickly, inexpensively and accurately is more important than ever. Commercially-available event-based systems exist that claim to achieve this goal; however, they collect little to no continuous-time data and primarily indicate when a pre-determined acceleration threshold has been exceeded under the unvalidated assumption that a potentially concussive blow has occurred. Recent findings by the Purdue Neurotrauma Group (PNG) have indicated that repeated exposure to both concussive and subconcussive blows can result in cumulative trauma disorder. To track …

Biomechanics And Relaxivity For Functional Imaging Of Articular Cartilage Injury And Degradation, Kateri Elizabeth Fites

Open Access Theses

Osteoarthritis (OA) is a major debilitating health concern and economic burden worldwide, affecting 27 million people in the United States alone. OA often follows tissue injury, and is marked by changes in the structure and biomechanical function of cartilage, including breakdown of extracellular matrix molecules, loss of bulk tissue stiffness, and increase in articular surface friction and wear. Unlike bone and many other tissues, cartilage lacks an intrinsic capacity for regeneration. Advanced OA is typically diagnosed by patient symptoms (e.g. joint pain) and confirmed by radiographic evaluation of joint space narrowing. However, the application of functional imaging to assess cartilage …

Developing An Embedded System Solution For High-Speed, High-Capacity Data Logging For A Size-Constrained, Low-Power Biomechanical Telemetry System And Investigating Components For Optimal Performance, Brandon Blaine Gardner

Open Access Theses

The Purdue Neurotrauma Group (PNG) seeks to develop a biomechanical telemetry system capable of monitoring and storing athletes' head motions with the intention of identifying when a player may be at risk of neurophysiological damage, especially brain damage. A number of commercially-available systems exist with a similar goal; however, each of these systems discards information below an acceleration threshold. Research by PNG indicates that any acceleration may contribute to brain damage and that, because of this, an event-based model is insufficient for a proper understanding of an athlete's neurophysiological health. Continuous-time monitoring of head accelerations is therefore necessary. To facilitate …

Characterizing Habituation Using The Time-On-Task Metric In An Iris Recognition System, Jacob A. Hasselgren

Open Access Theses

This thesis presents a characterization of biometric habituation in an iris recognition study using qualitative analysis of a distributed habituation survey and quantitative analysis of iris images collected in 2010 and 2012. The performed analyses answered the following two questions: a) How consistently does the biometric community define habituation?; and b) Does the time-on-task variable provide enough evidence to indicate the existence of habituation in an iris recognition system? The qualitative analysis examined responses to 12 habituation-related questions from 13 biometric experts to identify common themes that not only determined definition consistency but also characterized critical components often omitted from …

Controlling Protein Release Using Biodegradable Microparticles, Benjamin Patrick Kline

Open Access Theses

Research in the field of protein therapeutics has exploded over the past decade and continues to grow in both academia and in industry. Protein drugs have advantages of being highly specific and highly active making them coveted targets for high profile disease states like cancer and multiple sclerosis. Unfortunately, their many advantages are complemented by their obstacles. Because proteins are highly active and highly specific, the window between efficacy and toxicity is very narrow and drug development can be long and arduous. In addition, protein activity is dependent on its specific folding conformation that is easily disrupted by a variety …

Computer Modeling And Simulation Of Implantable Medical Device Heating Due To Mri Gradient Coil Fields, Bryan David Stem

Open Access Theses

For patients with implantable medical devices, the ability to safely undergo MRI scanning is critical to ensuring the highest standard of care. The gradient coils of an MRI generate kilohertz frequency, time varying magnetic fields. These magnetic fields induce a voltage on the external case of metallic, implantable medical devices through electromagnetic induction. Since the magnetic field generated by a gradient coil is time varying, the induced voltage results in the flow of eddy currents which can cause heating effects. These heating effects have been successfully modeled using ANSYS Maxwell and ANSYS Mechanical software packages.

The multi-physics simulation and solution …