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- All Subjects: Biomedical Engineering
- Genre: Masters Thesis
Description
Virtual environments are used for many physical rehabilitation and therapy purposes with varying degrees of success. An important feature for a therapy environment is the real-time monitoring of a participants' movement performance. Such monitoring can be used to evaluate the environment in addition to the participant's learning. Methods for monitoring and evaluation include tracking kinematic performance as well as monitoring muscle and brain activities through EMG and EEG technology. This study aims to observe trends in individual participants' motor learning based on changes in kinematic parameters and use those parameters to characterize different types of learners. This information can then guide EEG/EMG data analysis in the future. The evaluation of motor learning using kinematic parameters of performance typically compares averages of pre- and post-data to identify patterns of changes of various parameters. A key issue with using pre- and post-data is that individual participants perform differently and have different time-courses of learning. Furthermore, different parameters can evolve at independent rates. Finally, there is great variability in the movements at early stages of learning a task. To address these issues, a combined approach is proposed using robust regression, piece-wise regression and correlation to categorize different participant's motor learning. Using the mixed reality rehabilitation system developed at Arizona State University, it was possible to engage participants in motor learning, as revealed by improvements in kinematic parameters. A combination of robust regression, piecewise regression and correlation were used to reveal trends and characterize participants based on motor learning of three kinematic parameters: trajectory error, supination error and the number of phases in the velocity profile.
ContributorsAttygalle, Suneth Satoshi (Author) / He, Jiping (Thesis advisor) / Rikakais, Thanassis (Committee member) / Iasemidis, Leonidas (Committee member) / Arizona State University (Publisher)
Created2010
Description
The objective of this research is to investigate the relationship among key process design variables associated with the development of nanoscale electrospun polymeric scaffolds capable of tissue regeneration. To date, there has been no systematic approach toward understanding electrospinning process parameters responsible for the production of 3-D nanoscaffold architectures with desired levels quality assurance envisioned to satisfy emerging regenerative medicine market needs. , As such, this study encompassed a more systematic, rational design of experiment (DOE) approach toward the identification of electrospinning process conditions responsible for the production of dextran-polyacrylic acid (DEX-PAA) nanoscaffolds with desired architectures and tissue engineering properties. The latter includes scaffold fiber diameter, pore size, porosity, and degree of crosslinking that together can provide a range of scaffold nanomechanical properties that closely mimics the cell microenvironment. The results obtained from this preliminary DOE study indicate that there exist electrospinning operation conditions capable of producing Dex-PAA nanoarchitecture having potential utility for regenerative medicine applications.
ContributorsEspinoza, Roberta (Author) / Pizziconi, Vincent (Thesis advisor) / Massia, Stephen (Committee member) / Garcia, Antonio (Committee member) / Arizona State University (Publisher)
Created2013
Description
The overall goal of this research project was to assess the feasibility of investigating the effects of microgravity on mineralization systems in unit gravity environments. If possible to perform these studies in unit gravity earth environments, such as earth, such systems can offer markedly less costly and more concerted research efforts to study these vitally important systems. Expected outcomes from easily accessible test environments and more tractable studies include the development of more advanced and adaptive material systems, including biological systems, particularly as humans ponder human exploration in deep space. The specific focus of the research was the design and development of a prototypical experimental test system that could preliminarily meet the challenging design specifications required of such test systems. Guided by a more unified theoretical foundation and building upon concept design and development heuristics, assessment of the feasibility of two experimental test systems was explored. Test System I was a rotating wall reactor experimental system that closely followed the specifications of a similar test system, Synthecon, designed by NASA contractors and thus closely mimicked microgravity conditions of the space shuttle and station. The latter includes terminal velocity conditions experienced by both innate material systems, as well as, biological systems, including living tissue and humans but has the ability to extend to include those material test systems associated with mineralization processes. Test System II is comprised of a unique vertical column design that offered more easily controlled fluid mechanical test conditions over a much wider flow regime that was necessary to achieving terminal velocities under free convection-less conditions that are important in mineralization processes. Preliminary results indicate that Test System II offers distinct advantages in studying microgravity effects in test systems operating in unit gravity environments and particularly when investigating mineralization and related processes. Verification of the Test System II was performed on validating microgravity effects on calcite mineralization processes reported earlier others. There studies were conducted on calcite mineralization in fixed-wing, reduced gravity aircraft, known as the `vomit comet' where reduced gravity conditions are include for very short (~20second) time periods. Preliminary results indicate that test systems, such as test system II, can be devised to assess microgravity conditions in unit gravity environments, such as earth. Furthermore, the preliminary data obtained on calcite formation suggest that strictly physicochemical mechanisms may be the dominant factors that control adaptation in materials processes, a theory first proposed by Liu et al. Thus the result of this study may also help shine a light on the problem of early osteoporosis in astronauts and long term interest in deep space exploration.
ContributorsSeyedmadani, Kimia (Author) / Pizziconi, Vincent (Thesis advisor) / Towe, Bruce (Committee member) / Alford, Terry (Committee member) / Arizona State University (Publisher)
Created2013
Description
Encapsulation is a promising technology to deliver cell-based therapies to patients safely and with reduced need for immunosuppression. Macroencapsulation devices are advantageous due to their ease of retrieval, and thus enhanced safety profile, relative to microencapsulation techniques. A major challenge in macroencapsulation device design is ensuring sufficient oxygen transport to encapsulated cells, requiring high surface area-to-volume device geometries. In this work, a hydrogel injection molding biofabrication method was modified to design and generate complex three-dimensional macroencapsulation devices that have greater complexity in the z-axis. The rheological properties of diverse hydrogels were evaluated and used to perform computational flow modeling within injection mold devices to evaluate pressure regimes suitable for cell viability. 3D printed device designs were evaluated for the reproducibility of hydrogel filling and extraction. This work demonstrated that injection molding biofabrication to construct complex three-dimensional geometries is feasible in pressure regimes consistent with preserving cell viability. Future work will evaluate encapsulated cell viability after injection molding.
ContributorsBrowning, Blake (Author) / Weaver, Jessica D (Thesis advisor) / Vernon, Brent (Committee member) / Nikkhah, Mehdi (Committee member) / Arizona State University (Publisher)
Created2022
Description
Skin wounds can be caused by traumatic lacerations or incisions which disrupt the structural and functional integrity of the skin. Wound closure and primary intention treatment of the wound as soon as possible is crucial to avoid or minimize the risk of infection that can result in a compromised healing rate or advanced functional intricacy. The gold standard treatment for skin wound healing is suturing. Light-activated tissue sealing is an appealing alternative to sutures as it seals the wound edges minimizing the risk of infection and scarring, especially when utilized along with biodegradable polymeric biomaterials in the wound bed. Silk fibroins can be used as a biodegradable biomaterial that possesses properties supporting cell migration and proliferation in the tissue it interacts with. In addition, histamine treatment is shown to have extensive effects on cellular functions promoting wound healing. Here, the evaluation of Laser-activated Sealants (LASE) consisting of silk fibroin films induced with Indocyanine Green dye in a wound sealed with laser in the presence of Histamine receptor agonists H1R, H2R and H4R take place. The results were evaluated using Trans-epidermal Water Loss (TEWL), histological and analytical techniques where immune cell biomarkers Arginase-1, Ly6G, iNOS, Alpha-SMA, Proliferating Cell Nuclear Antigen (PCNA), and E-Cadherin were used to study the activity of specific cells such as macrophages, neutrophils, and myofibroblasts that aid in wound healing. PBS was used as a control for histamine receptor agonists. It was found that TEWL increased when treated with H1 receptor agonists while decreasing significantly in H2R and H4R-treated wounds. Arginase-1 activity improved, while it displayed an inverse relationship compared to iNOS. H4R agonist escalated Alpha-SMA cells, while others did not have any significant difference. Ly6G activity depleted in all histamine agonists significantly, while PCNA and E-Cadherin failed to show a positive or negative effect.
ContributorsPatel, Dirghau Manishbhai (Author) / Rege, Kaushal (Thesis advisor) / Massia, Stephen (Committee member) / Brafman, David (Committee member) / Arizona State University (Publisher)
Created2022
Description
Portable health diagnostic systems seek to perform medical grade diagnostics in non-ideal environments. This work details a robust fault tolerant portable health diagnostic design implemented in hardware, firmware and software for the detectionof HPV in low-income countries. The device under device under test (DUT) is a fluorescence based lateral flow assay (LFA) point-of-care (POC) device. This work’s contributions are: firmware and software development, calibration routine implementation, device performance characterization and a proposed method of in-software fault detection. Firmware was refactored from the original implementation of the POC fluorescence reader to expose an application programming interface (API) via USB. Companion software available for desktop environments (Windows, Mac and Linux) was created to interface with this firmware API and conduct macro level routines to request and receive fluorescence data while presenting a user-friendly interface to clinical technicians. Lastly, an environmental chamber was constructed to conduct sequential diagnostic reads in order to observe sensor drift and other deviations that might present themselves in real-world usage. The results from these evaluations show a standard deviation of less than 1% in fluorescence readings in nominal temperature environments (approx. 25C) suggesting that this system will have a favorable signal-to-noise (SNR) ratio in such a setting. In non-ideal over heated environments (≥38C), the evaluation results showed performance degradation with standard deviations as large as 15%.
ContributorsLue Sang, Christopher David (Author) / Blain Christen, Jennifer M (Thesis advisor) / Ozev, Sule (Committee member) / Goryll, Michael (Committee member) / Raupp, Gregory (Committee member) / Arizona State University (Publisher)
Created2022
Description
Neural tissue is a delicate system comprised of neurons and their synapses, glial cells for support, and vasculature for oxygen and nutrient delivery. This complexity ultimately gives rise to the human brain, a system researchers have become increasingly interested in replicating for artificial intelligence purposes. Some have even gone so far as to use neuronal cultures as computing hardware, but utilizing an environment closer to a living brain means having to grapple with the same issues faced by clinicians and researchers trying to treat brain disorders. Most outstanding among these are the problems that arise with invasive interfaces. Optical techniques that use fluorescent dyes and proteins have emerged as a solution for noninvasive imaging with single-cell resolution in vitro and in vivo, but feeding in information in the form of neuromodulation still requires implanted electrodes. The implantation process of these electrodes damages nearby neurons and their connections, causes hemorrhaging, and leads to scarring and gliosis that diminish efficacy. Here, a new approach for noninvasive neuromodulation with high spatial precision is described. It makes use of a combination of ultrasound, high frequency acoustic energy that can be focused to submillimeter regions at significant depths, and electric fields, an effective tool for neuromodulation that lacks spatial precision when used in a noninvasive manner. The hypothesis is that, when combined in a specific manner, these will lead to nonlinear effects at neuronal membranes that cause cells only in the region of overlap to be stimulated. Computational modeling confirmed this combination to be uniquely stimulating, contingent on certain physical effects of ultrasound on cell membranes. Subsequent in vitro experiments led to inconclusive results, however, leaving the door open for future experimentation with modified configurations and approaches. The specific combination explored here is also not the only untested technique that may achieve a similar goal.
ContributorsNester, Elliot (Author) / Wang, Yalin (Thesis advisor) / Muthuswamy, Jitendran (Committee member) / Towe, Bruce (Committee member) / Arizona State University (Publisher)
Created2022
Description
In the realm of biosensors and nanotechnology, deoxyribonucleic acid (DNA) nanosensors have demonstrated tremendous potential across diverse real-world applications, from environmental monitoring to healthcare diagnostics. Fabrication of nanosensors allows assembling and designing of DNA molecules at nanoscale with high precision and versatility. Such fabricating DNA nanosensors are quite time consuming. Hence it is important to store them in batches. However synthetic DNA molecules can be prone to degradation over time, especially when exposed to various environmental factors like light, heat, or any other chemical contaminants. To address this issue, a shelf life study of DNA nanosensors using various lyoprotectant conditions was carried out to determine the long term stability of such sensors. This study involves fabrication of the dendritic, double - stranded DNA nanosensors involving five strands L1 through L5 conjugated with pHAb fluorophores via N-hydroxysuccinimide ester reaction and acetylcholinesterase (AChE) enzyme, a core component of the sensor. This sensor was originally a fluorescent ACh-selective nanosensors designed to accommodate the BTX ligand, AChE to image the ACh release in the submandibular region of the living mice to report real time quantitative endogenous ACh release triggered by electrical stimulation. AChE enzyme is a good receptor to detect acetylcholine release in the Peripheral Nervous System (PNS). The primary objective of the study was to assess DNA nanosensors with AChE, however due to the intricate interactions, non-specific binding and cost-effectiveness, the shelf life study was carried out separately. The shelf study includes observing DNA nanosensors with different disaccharide lyoprotectants like trehalose and sucrose that were analyzed under different temperature conditions: room temperature (25ºC) and at 50 ºC for different time intervals, over a week time. Also, Observing AChE with various protectants under 50 ºC with and without lyoprotectants for various time intervals like 24 hours and 48 hours. To replicate the real-world transit scenarios, the study also involves test-shipment of the samples with lyoprotectants for 2-3 days to both cross-country and local (in-state). As a result, the use of lyoprotectants, particularly trehalose, has proven to be more resilient and effective in preserving the stability and integrity of DNA nanosensors and Acetylcholinesterase (AChE) enzymes
ContributorsSrinivasan, Nikita (Author) / Clark, Heather A (Thesis advisor) / Ma, Kristine Y (Committee member) / Beeman, Scott (Committee member) / Arizona State University (Publisher)
Created2023
Description
Evolving knowledge about the tumor microenvironment (TME) is driving innovation in designing novel therapies against hard-to-treat breast cancer. Addressing the immune elements within the tumor microenvironment (TME) has emerged as a highly encouraging strategy for treating cancer. Although current immunotherapies have made advancements in reinstating the body's ability to fight tumors, the search for effective cancer treatments to combat tumor evasion remains a formidable challenge. In line with this objective, there is a pressing need to better understand the complex tumor-immune dynamics and crosstalk within the TME. To evaluate the cancer-immune interaction, this study aimed at investigating the crosstalk between naïve macrophages and cytotoxic T cells in driving tumor progression using an organotypic 3D ex vivo tumor on-a-chip model. The presented microfluidic platform consists of two distinct regions namely: The tumor region and the stroma region separated by trapezoidal microposts to ensure interconnectivity between regions thereby incorporating high spatial organization. In the established triculture platform, the complex Tumor Immune Microenvironment was successfully recapitulated by incorporating naïve macrophage and T cells within an appropriate 3D matrix. Through invasion and morphometric analyses, definitive outcomes were obtained that underscore the significant contribution of macrophages in facilitating tumor progression. Furthermore, the inclusion of T cells led to a notable decrease in the migratory speed of cancer cells and macrophages, underscoring the reciprocal communication between these two immune cell populations in the regulation of tumor advancement. Overall, this study highlights the complexity of TME and underscores the critical role of immune cells in regulating cancer progression.
ContributorsManoharan, Twinkle Jina Minette (Author) / Nikkhah, Mehdi (Thesis advisor) / Acharya, Abhinav P (Committee member) / Wang, Shaopeng (Committee member) / Arizona State University (Publisher)
Created2023
Description
Magnetic resonance imaging (MRI) is the most powerful instrument for imaging anatomical structures. One of the most essential components of the MRI scanner is a radiofrequency (RF) coil. It induces resonant phenomena and receives the resonated RF signal from the body. Then, the signal is computed and reconstructed for MR images. Therefore, improving image quality by increasing the receiver's (Rx) efficiency is always remarkable. This research introduces a flexible and stretchable receive RF coil embedded in a dielectric-loaded material. Recent studies show that the adaptable coil can improve imaging quality by flexing and stretching to fit well with the sample's surface, reducing the spatial distance between the load and the coil. High permittivity dielectric material positioned between the coil and phantom was known to increase the RF field distribution's efficiency significantly. Recent studies integrating the high dielectric material with the coil show a significant improvement in signal-to-noise ratio (SNR), which can improve the overall efficiency of the coil. Previous research also introduced new elastic dielectric material, which shows improvement in uniformity when incorporated with an RF coil. Combining the adaptable RF coil with the elastic dielectric material has the potential to enhance the coil's performance further. The flexible dielectric material's limitations and unknown interaction with the coil pose a challenge. Thus, each component was integrated into a simple loop coil step-by-step, which allowed for experimentation and evaluation of the performance of each part. The mechanical performance was tested manually. The introduced coil is highly flexible and can stretch up to 20% of its original length in one direction. The electrical performance was evaluated in simulations and experiments on a 9.4T MRI scanner compared to conventional RF coils.
ContributorsHerabut, Chavalchart (Author) / Sohn, SungMin (Thesis advisor) / Sadleir, Rosalind (Committee member) / Beeman, Scott (Committee member) / Arizona State University (Publisher)
Created2023