Biomedical Engineering and Bioengineering Commons^™

Device Design Factors For Enhancing The Functionality Of Chronic Intracortical Microelectrodes, Heui Chang Lee

Open Access Dissertations

Intracortical microelectrodes are devices used in brain-computer interfaces (BCI) to help regain lost motor, sensory, and cognitive functions of individuals with neurological disorders. However, the long-term performance of microelectrode arrays is hampered by a series of inflammatory tissue responses. The consequence of the inflammatory response is the formation of a dense astroglial sheath around the vicinity of the electrode, impeding the electrical conduction between the electrode and neurons. Furthermore, due to the cascade of neuroinflammatory events, the number of neurons is significantly reduced near the electrode, manifested by decrease in signal-to-noise ratio (SNR) and the yield of electrodes. Over time, …

Characterizing The Effects Of Repetitive Head Trauma In Female Soccer Athletes For Prevention Of Mild Traumatic Brain Injury, Diana Otero Svaldi

Open Access Dissertations

As participation in women’s soccer continues to grow and the longevity of female athletes’ careers continues to increase, prevention of mTBI in women’s soccer has become a major concern for female athletes as the long-term risks associated with a history of mTBI are well documented. Among women’s sports, soccer exhibits the highest concussion rates, on par with those of men’s football at the collegiate level. Head impact monitoring technology has revealed that “concussive hits” occurring directly before symptomatic injury are not predictive of mTBI, suggesting that the cumulative effect of repetitive head impacts experienced by collision sport athletes should be …

Dynamic Holography In Semiconductors And Biomedical Optics, Hao Sun

Open Access Dissertations

Three-dimensional scanning and display are rapidly-advancing new technologies with important commercial drivers such as 3D printing and remote imaging for big data applications. Holography is a natural approach to recording and displaying three-dimensional information because it uses phase-sensitive interferometry to record interference patterns when a reference beam encounters coherent light arriving from an object. The 3D information is contained in the values of wave optics. Holography is a broad field that goes beyond recording and displaying. For instance, holographic optical elements, which take advantage of holographic imaging principles, perform the functions of lenses, gratings or mirrors. Holographic interferometry is also …

Mathematical Analysis Of Feedback Targets Of Bmp Signaling In Drosophila Embryonic Development, Yan Luo

Open Access Theses

Bone morphogenetic proteins (BMPs) drive a range of cellular processes especially in the early stages of embryonic development. This family of proteins acts as one of the most important extracellular signals in development pattern formation across the animal kingdom. Cells in embryos differentiate into different cell types in response to the concentration level of BMP. This complex process is regulated by multiple regulators that serve to tune the signal response.

Extensive experimental and computational research has been performed to analyze BMP regulation in Drosophila, a widely studied model organism, and has advanced our understanding of animal development. Because of …

Concurrent Detection And Isolation Of Cellular And Molecular Biomarkers, Wanfeng Huang

Open Access Dissertations

Detection of cancer markers such as protein biomolecules and cancer cells in bodily fluids is of great importance in early diagnosis, prognosis as well as evaluation of therapy efficacy. Numerous devices have been developed for detecting either cellular or molecular targets, however there has not yet been a system that can simultaneously detect both cellular and molecular targets effectively. Molecule and cell-based assays are important because each type of target can tell a different story about the state of the disease and the two types of information can potentially be combined and/or compared for more accurate biological or clinical assessments. …

Laser-Processed Parchment Paper For Fabrication Of Chronic Wound Dressings With Selective Oxygenation, Manuel Ochoa

Open Access Dissertations

Chronic non-healing wounds (e.g., diabetic foot ulcers and bed sores) impact over 6.5 million Americans per year, costs in excess of $25 billion to treat on an annual basis, and are on the rise due to increasing levels of obesity and diabetes compounded by an aging population. A major inhibitor of healing is suboptimal oxygenation of the wound bed. Unlike acute injuries that receive sufficient oxygen via a functional blood vessel network, chronic wounds often suffer from the lack of a proper vascular network; thus being incapable of providing sufficient oxygen for tissue growth. Typical medical treatment of hypoxic chronic …

Optical Dosimetry Tools And Monte Carlo Based Methods For Applications In Image Guided Optical Therapy In The Brain, Akshay N Prabhu Verleker

Open Access Dissertations

Purpose: The long-term goal of this research is to determine the feasibility of using near infra-red light to stimulate drug release in metastatic lesions within the brain. In this work, we focused on developing the tools needed to quantify and verify photon fluence distribution in biological tissue. To accomplish this task, an optical dosimetry probe and Monte Carlo based simulation code were fabricated, calibrated and developed to predict light transport in heterogeneous tissue phantoms of the skull and brain. Empirical model (EM) of photon transport using CT images as input were devised to provide real-time calculations capable of being translated …

The Role Of Mechanical Loading In Chondrocyte Signaling Pathways, Qiaoqiao Wan

Open Access Dissertations

Chondrocytes are a predominant cell type present in articular cartilage, whose integrity is jeopardized in joint degenerative diseases such as osteoarthritis (OA). In the chondrocytes of patients with OA, the elevated levels of inflammatory cytokines such as interleukin 1β (IL1β) and tumor necrosis factor α (TNFα) have been reported. These cytokines contribute to degradation of cartilage matrix by increasing activities of proteolytic enzymes. In addition to their contribution to proteolytic enzymes, these cytokines adversely affect anabolic activity of chondrocytes by inhibiting the production of proteoglycans and type II collagen. Therefore, blocking the action of these cytokines is a potential strategy …

Development Of A Fluidic Mixing Nozzle For 3d Bioprinting, Will Hoggatt

Open Access Theses

3D bioprinting is a relatively new and very promising field that uses conventional 3D printing techniques and adapts them to print biological materials that are suited for use with cells. These bioprinters can be used to print cells encapsulated within biological "ink" (bio-ink) to create and customize complex three-dimensional tissues and organs. Our work has focused on developing a new bioprinter nozzle that addresses critical gaps with present-day bioprinters, namely, the lack of standardized, physiologically-relevant biomaterials, and their one nozzle per composition printing capacity. These shortcomings preclude printing a range of cellular and biomaterial compositions (including gradients of cells and …

Development Of Orthogonally Crosslinked Thiol-Ene Hydrogels For Encapsulation Of Pancreatic Beta-Cells, Han Shih

Open Access Dissertations

Type I diabetes mellitus (T1DM) is an autoimmune disease caused by auto-reactive T-cell-mediated destruction of insulin-producing β-cells. Effective encapsulation strategies can protect the transplanted islets from direct attack by host immune cells while maintaining insulin secretion. To achieve this goal, I have developed a hydrogel conformal coating using a visible light-mediated interfacial thiol-ene photopolymerization. Unlike conventional chain-growth visible light polymerizations, no additional cytotoxic co-initiator or co-monomer was required in thiol-ene gelation scheme for rapid gelation. More importantly, islets coated with thiol-ene gel maintained their viability and function in vitro. In addition to microencapsulate β-cells, the second objective of my …

Influence Of The 3d Microenvironment On Glioblastoma Migration And Drug Response, Ruth Marisol Herrera Perez

Open Access Dissertations

Glioblastoma (GBM) is a highly invasive brain cancer characterized by poor prognosis. Despite significant efforts by the basic and clinical research community our understanding of GBM progression and recurrence has been incremental. Improvements in therapeutic response have been dismal, and GBM continues to be the deadliest tumor of the central nervous system, with patient average survival rate of 12 months. Synergistic relationships that the tumor cells establish with the brain microenvironment have been proven fundamental for successful tumor progression and maintenance. Yet, many in vitro GBM studies are performed in formats that fail to recapitulate the most essential component of …

Direct Drug Screening And Lipid Profiling Using Ambient Mass Spectrometry, Yuan Su

Open Access Dissertations

Mass spectrometry (MS) stands in an outstanding position in analysis of biological specimens owing to its abundant structural information, high accuracy, incomparable sensitivity, high speed, and the large variety of its applications. The ion source, an instrumental part for converting the analyte into ions, has played an important role in analyzing biological specimens by MS. However, the performance of conventional spray-based ionization methods always suffers from chemical interferences derived from complex biological matrices. A series of sample extraction, purification, and separation steps is required before the ionization, so as to ensure excellent performance of MS analysis. In order to simplify …

Consonant Discrimination In The Inferior Colliculus Of Young And Aged Rats, Christopher S. Soverns

Open Access Theses

Complex acoustic stimuli are thoroughly encoded and processed along the primary auditory pathway to give reliable and relevant information about the environment, and elucidating the neural coding mechanisms is essential to informing clinical attempts to combat auditory dysfuntion. Receiving a uniquely diverse set of ascending and descending inputs, the inferior colliculus (IC) is a site of intricate temporal processing. In this work, natural and modified human speech is used to investigate discrimination of voice onset time (VOT) in the spiking output of IC neurons. A template-matching classification model is proposed in which single stimulus presentation responses are correlated with aggregate …

Optimization Of Wireless Power Networks For Biomedical Applications, Kyle A. Thackston

Open Access Theses

Successful physiological integration of electronics will open the doors to new methods of treatment and diagnoses. One of the key challenges of this integration is designing devices as small as possible while still maintaining high functionality, such as bio-signal recording, processing, telemetry, and stimulation. Wireless power transfer (WPT) can help shrink a device’s footprint by removing the need for bulky batteries. While many modalities of WPT exist for biomedical applications, the optimal power transfer efficiency (PTE) is seldom achieved due to improper impedance matching. Existing methods for determining the optimal impedance matching conditions tend to be application specific and make …

Densified Collagen-Fibril Biomaterials For Bone Tissue Engineering, Lauren E. Watkins

Open Access Theses

Millions of craniofacial bone defects occur annually as a result of trauma, congenital defects, disease, or tooth extraction. When present in the oral cavity, these defects are associated with adverse impacts on speech, mastication, and aesthetics. Thus, there is a clinical need for interventional strategies to restore and preserve alveolar bone mass to improve the success of future treatment options intended to reestablish functionality and aesthetics. Guided bone regeneration using bone grafts and a membrane represent the current standard of care for repairing alveolar bone defects, but face a number of limitations related to resorption time and structural integrity. Improvements …

Improving The Mechanistic Study Of Neuromuscular Diseases Through The Development Of A Fully Wireless And Implantable Recording Device, Rebecca A. Bercich

Open Access Dissertations

Neuromuscular diseases manifest by a handful of known phenotypes affecting the peripheral nerves, skeletal muscle fibers, and neuromuscular junction. Common signs of these diseases include demyelination, myasthenia, atrophy, and aberrant muscle activity—all of which may be tracked over time using one or more electrophysiological markers. Mice, which are the predominant mammalian model for most human diseases, have been used to study congenital neuromuscular diseases for decades. However, our understanding of the mechanisms underlying these pathologies is still incomplete. This is in part due to the lack of instrumentation available to easily collect longitudinal, in vivo electrophysiological activity from mice. There …

Advancing Multiple Model-Based Control Of Complex Biological Systems: Applications In T Cell Biology, Jeffrey P. Perley

Open Access Dissertations

Activated CD4+ T cells are important regulators of the adaptive immune response against invading pathogens and cancerous host cells. The process of activation is mediated by the T cell receptor and a vast network of intracellular signal transduction pathways, which recognize and interpret antigenic signals to determine the cell's response. The critical role of these early signaling events in normal cell function and the pathogenesis of disease ultimately make them attractive therapeutic targets for numerous autoimmune diseases and cancers.

Scientists increasingly rely on predictive mathematical models and control-theoretic tools to design effective strategies to manipulate cellular processes for the advancement …

Coupled Resonator Based Wireless Power Transfer For Bioelectronics, Henry Mei

Open Access Dissertations

Implantable and wearable bioelectronics provide the ability to monitor and modulate physiological processes. They represent a promising set of technologies that can provide new treatment for patients or new tools for scientific discovery, such as in long-term studies involving small animals. As these technologies advance, two trends are clear, miniaturization and increased sophistication i.e. multiple channels, wireless bi-directional communication, and responsiveness (closed-loop devices). One primary challenge in realizing miniaturized and sophisticated bioelectronics is powering. Integration and development of wireless power transfer (WPT) technology, however, can overcome this challenge.

In this dissertation, I propose the use of coupled resonator WPT for …

Supervised Learning-Based Explicit Nonlinear Model Predictive Control And Unknown Input Estimation In Biomedical Systems, Ankush Chakrabarty

Open Access Dissertations

Application of nonlinear control theory to biomedical systems involves tackling some unique and challenging problems. The mathematical models that describe biomedical systems are typically large and nonlinear. In addition, biological systems exhibit dynamics which are not reflected in the model (so-called 'un-modeled dynamics') and hard constraints on the states and control actions, which exacerbate the difficulties in designing model-based controllers or observers.

This thesis investigates the design of scalable fast explicit nonlinear model predictive controllers (ENMPCs). The design involves (i) the estimation of a feasible region using Lyapunov stability methods and support vector machines; and (ii) within the estimated feasible …

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 …

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 …

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 …