Theses

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Browsing Theses by Discipline "Biomedical Engineering"

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    A Model Long Acting Sentinel Gel for Early Management of Tumor Recurrence.
    (2019-04-29) Chen, Justin; Yevgeny Brudno, Chair; Ashley Brown, Member; Benhabbour, Rahima, Inter-Institutional
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    Adhesion and mechanobiology methods to proliferate and osteogenically differentiate adipose-derived adult stem cells
    (2007-11-30) Hanson, Ariel Dawn; Dr. Elizabeth G. Loboa, Committee Chair; Dr. Albert J. Banes, Committee Member; Dr. Behnam Pourdeyhimi, Committee Member
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    Altered Trabecular Microarchitecture near the Glenohumeral Joint of a Rat Model with Neonatal Brachial Plexus Injury
    (2017-06-28) McCormick, Carolyn Marie; Jacqueline Cole-Husseini, Co-Chair; Katherine Saul, Co-Chair; Gregory Sawicki, Member
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    An Explorative Study on How to Improve Mediolateral Balance Using Hip Exoskeleton.
    (2024-06-24) Yu, Zhenyuan; Ming Liu, Chair; Matthew Fisher, Member; Katherine Saul, Member
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    An Investigation into Dynamic Stability Measures to Quantify Human-Prosthesis Interaction.
    (2020-06-23) Lupiani, Ashling Ann; He Huang, Chair; Derek Kamper, Member; Katherine Saul, Member
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    Assessing the Immunogenicity of Various Cancer Ablations.
    (2025-03-11) Hamed, Ali Ayed; David Zaharoff, Chair; Imran Rizvi, Member; Mike Sano, Member
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    Characterization and Evaluation of a Novel Nanoporous Gold Biosensor Substrate.
    (2009-07-22) Pierson, Bonnie Elizabeth; Dr. Albert Banes, Committee Member; Dr. Roger Narayan, Committee Chair; Dr. Nancy Monteiro-Riviere, Committee Member
    Dilute but powerful biological markers, such as hormones in blood stream, are potent but difficult to detect quickly and accurately using current biosensor technologies. Nanoporous structures offer greatly increased surface area which can be functionalized for use as a biosensor, amplifying throughput and the enhancing the ability to detect small concentrations. With the option for diverse component materials and conformations, a sensor with prescribed properties could be easily incorporated into devices for clinical diagnosis or research applications. This study evaluates the suitability of a nanoporous gold (NPG) wire for use as a biosensing component as a proof of concept through the detailed characterization of the porosity, structural support, and electrical properties of the wires. The nanoporous gold wires were created using electrochemical etching equipment. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were used to image and evaluate the pores and effectiveness of the etching procedure. Pores were found to be 9.86 ± 4.92 µm in diameter with a density of 880 pores/µm2 and only 5% silver remained following etching procedures. The storage capacity of the nanoporous wire annealed to a gold support structure at 15.6 mF/cm, was found to be higher than that of unsupported wires at 10.6 mF/cm. Structurally supported NPG wires also demonstrated a lower resistance (4.2Ω compared to 13.4Ω) owing to the capacitance of the nonporous gold support structure at high frequencies. Wires annealed to a gold support structure demonstrated greater mechanical stability and generally more consistent electrical properties. Samples were found highly susceptible to fracture and any coatings vulnerable to denaturing with extensive transport, handling, and testing. Some cross-contamination of samples was detected. Most contamination effects were minimal and confined to materials used in the manufacturing process. Future investigation should include other support structure conformations, functionalizing samples, and performing biocompatibility testing. NPG wires demonstrate potential for environmental applications and as medical device component, but have not yet been evaluated for direct-contact in vivo applications. The brittleness of the material necessitates that it be used in conjunction with other support structures; however the material provides interesting electrical properties, a good base for the adhesion of biomolecules, and a thorough porosity.
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    Characterization of Microprinted Microgels on Functionalized Surfaces.
    (2017-05-01) Ngobili, Terrika Adaeze; Michael Daniele, Chair; Ashley Brown, Member; Matthew Fisher, Member
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    A Data-driven Muscle-tendon Modeling Framework to Evaluate Muscle-level Performance of Ankle Exoskeletons during Human Walking.
    (2013-08-02) Khan, Nabil Salih; Gregory Sawicki, Chair; Richard Goldberg, Member; Michael Lewek, Inter-Institutional
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    Decorating Extracellular Matrix with Click Chemistry Motifs to act as a Refillable Drug Depot.
    (2019-06-05) Adams, Mary Regan; Yevgeny Brudno, Chair; David Zaharoff, Member; Michael Sano, Member
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    Design and Implementation of a Tissue Compliant Thoracic Retractor.
    (2015-08-10) Verderber, Alexander Gerard; David Lalush, Co-Chair; Andrew DiMeo, Co-Chair; Jose Alberto Gines Zarza, Member
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    Design and In Vitro Evaluation of Five Epiphyseal Plate Fracture Stabilization Methods in Canines
    (2008-12-05) Lee, Erica Shengkai; Ola L.A. Harrysson, Committee Chair; Denis J. Marcellin-Little, Committee Co-Chair; Peter L. Mente, Committee Member
    Epiphyseal growth plate fractures of the distal femur are commonly seen in young canines that have not completed full ossification of the growth plate. Current treatment techniques involve the use of crossed Kirschner wires and commercial stainless steel plates. This raises concerns of either providing not enough stability or providing too much to the point where stress shielding is observed in the surrounding tissues or the full growth potential of the bone cannot be realized. To prevent this, a second surgery must be performed to remove these stabilization implants after proper healing of the fracture. Currently, resorbable polymers have been used to treat fractures, primarily in the cranio-maxillofacial area. This study aimed to mechanically evaluate the effectiveness of custom designed polycaprolactone (PCL) resorbable bilateral bone plates and lateral titanium plates to the current epiphyseal plate fracture repair techniques of crossed Kirschner wires and lateral commercial stainless steel bone plates. Forty identical models of the distal femur with pre-designed epiphyseal plate fractures were produced for the fixation of these five repair methods. The model constructs underwent nondestructive cranio-caudal bending, medio-lateral bending and torsional loading tests as well as destructive cranio-caudal bending and torsional loading failure tests. The study showed no statistically significant differences among the constructs for the destructive tests, suggesting the models failed prior to reaching the yield and ultimate strengths and torques of the actual constructs. However, from nondestructive tests, the constructs repaired with custom designed titanium plates displayed comparable mechanical properties to the commercial stainless steel plates. Structural stiffnesses of the titanium plate repaired constructs were not statistically significant from the commercial plate repaired constructs for nondestructive cranio-caudal bending medio-lateral bending and torsional loading tests. The study also displayed excellent mechanical properties of the two thicknesses (4mm and 2mm) of custom designed resorbable PCL plates. Results showed both 4mm and 2mm resorbable plates were statistically more structurally stiff when responding to cranial forces compared to Kirschner wire repaired fractures. Both 4mm and 2mm resorbable plates were also more structurally stiff when responding to medial forces compared to Kirschner wire repaired fractures and due to their bilateral attachment, also provided a marginally greater stability than the laterally attached metal plates. The resorbable 4mm and 2mm plate constructs were also marginally better in structural stiffness in response to torsional loading than the Kirschner wire constructs. Additionally, results indicated that the 2mm resorbable plate was statistically comparable to the thicker 4mm plate, in cranial bending, medial bending, and torsional bending. Custom designed titanium plates could be an effective alternative to commercial stainless steel plates for fractures observed by more mature canines, and both resorbable 4mm and 2mm PCL plates could be a more effective alternative to Kirschner wire epiphysis plate fracture repair techniques in young canines.
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    Design of An Expert System to Automatically Tune the Impedance Control for Powered Knee Prostheses.
    (2014-10-28) Wang, Ding; He Huang, Chair; Gregory Sawicki, Member; H Nagle, Member
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    Design of an Intelligent Compression Stocking for Reducing Ulcer Healing Time
    (2009-03-03) Hegarty, Meghan Sarah; Dr. Edward Grant, Committee Chair; Dr. Carol Giuliani, Committee Member; Dr. Brooke Steele, Committee Member
    Venous leg ulcers remain a problem in the United States, costing the health care industry nearly $1 billion annually. A major portion of this spending is incurred as a result of prolonged healing time. Compression therapy is known to promote recovery. This technique may be improved by allowing for dynamic customization of treatment parameters. The design of a sensing system for an intelligent compression stocking is described in this thesis. This sensing system will eventually serve as a means by which to quantify the performance of the stocking through the continuous measurement of key physiological variables. Blood flow velocity will be measured using an acoustic array, and leg volume will be quantified using bio-impedance techniques. Preliminary experiments were conducted in order to verify the responsiveness and practicality of using these technologies to monitor ulcer healing. The Edema Monitoring System was capable of resolving small changes in leg volume resulting from artificially-induced swelling. Unfortunately, the Acoustic Blood Flow Measurement System did not perform acceptably in terms of accuracy and robustness. Future directions for this technology include finding a more acceptable means by which to measure blood flow velocity, improving the sensing system by incorporating additional optimization parameters, exploring the use of alternative actuation mechanisms, and expanding its use to encompass all medical-grade compression stockings.
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    Determination of Impedance Boundary Conditions for the Pulmonary Vasculature
    (2007-04-27) Clipp, Rachel Betany; Dr. Brooke N. Steele, Committee Chair; Dr. Carol Lucas, Committee Member; Dr. Mette Olufsen, Committee Member
    Computational modeling can be used to achieve a better understanding of fluid analysis within the pulmonary circulation. Boundary conditions are used in fluid analysis to determine the pressure and flow profiles of the blood as it moves through the lung. Accurate boundary conditions are critical in providing accurate models of blood pressure and blood flow. An important consideration when determining boundary conditions for the pulmonary vasculature is the effect of respiration on the impedance of the pulmonary vasculature. An additional consideration for the pulmonary vasculature is the physiologic differences between the pulmonary circulation and that of the systemic circulation. This research determines impedance boundary conditions for the pulmonary vasculature that reflect the specific geometry of the lung and correspond to maximal inspiration and maximal expiration. The analysis was performed using an existing one-dimensional finite element analysis system. The boundary conditions were defined by a bifurcating structure tree with a number of variables that were used to change the resistance of the pulmonary vessels. The variables within the structure tree were altered to reflect the differences between the pulmonary circulation and the systemic circulation. These variables include the length to radius ratio of the vessels in the structure tree and the asymmetry as the branches. A respiration factor was used to scale the vessels of the structure tree to reflect the effects of respiration on the geometry of the lung. The compliance of the vessels was also changed to reflect the more distensible vessels found in the pulmonary system. The geometry of the lung was defined with the structured tree parameters at maximal inspiration and the respiration factor was used to scale the defined geometry and reflect maximal expiration. The parameters were determined by utilizing an optimization technique. The Levinberg-Marquardt least-squares non-linear optimization algorithm was used to find a set of non-unique optimal parameters. The computed data was validated using measured pressure and flow data collected in a previous study.
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    Development and Evaluation of the GIDEI USB Interface Device
    (2008-11-15) Burkholder, Adam Bresler; Stephen Bruce Knisley, Committee Member; Richard L. Goldberg, Committee Chair; Henry S. Hsiao, Committee Member
    Individuals affected by a variety of conditions, including progressive neurological disorders and strokes, frequently experience the loss of the ability to speak. Augmentative and alternative communication (AAC) devices aid these individuals by utilizing speech synthesis technology to speak pre-programmed words and phrases as well as user-entered text. Many of these individuals have also lost a great deal of muscle control and range of motion, and are unable to operate a computer using a traditional keyboard and mouse. To facilitate the use of computers by AAC users, the General Input Device Emulating Interface (GIDEI) was developed by the Trace Research and Development Center at the University of Wisconsin. This communication protocol utilizes the standard RS-232 serial port, ubiquitous in computers at the time of development, and defined a standard method by which AAC devices were to emulate a mouse and keyboard. This allowed a standard set of drivers to be developed and implemented on almost any computing platform. However, because serial ports are largely being phased out in favor of USB and support for the GIDEI protocol in newer operating systems is poor, new methods are necessary to allow continued support of this functionality. For this reason, a USB 1.1 compatible human interface device (HID) was developed to act as a transparent bridge between AAC devices and personal computers. The device was evaluated for both its ability to adhere to requirements of the USB and GIDEI specifications and its ability to be effectively used by the intended population. To this end, two testing protocols were developed. The first was performed by the developer, and was designed to utilize every aspect of the GIDEI protocol. The second was performed by AAC users recruited from Duke University?s ALS clinic, and was designed to include most of the mouse and keyboard tasks utilized during normal operation of a computer. Nearly every step throughout four trials of each test protocol was able to be completed successfully. While further development is necessary, these results indicate that the device is a potentially viable solution for AAC users wishing to take advantage of GIDEI functionality to access current computers.
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    Development of Titanium Alloy Mesh Structures for Canine Radial Endoprosthesis.
    (2016-03-21) Thompson, Joy Camille; Ola Lars Harrysson, Co-Chair; Denis Marcellin, Co-Chair; Gregory Sawicki, Member
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    Directed Self Assembly of Nanospheres for NanoLithography and Nanostructured Surface Plasmon Sensors
    (2008-04-08) McGlade, John E; John Muth, Committee Chair; Orlin Velev, Committee Member; David Lalush, Committee Co-Chair
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    Dissolvable Polymeric Microneedles for Insulin Delivery.
    (2014-05-08) DiSanto, Rocco Michael; Zhen Gu, Chair; Glenn Walker, Member; Frances Ligler, Member