Biomedical Engineering and Bioengineering Commons^™

Longitudinal Oxygen Imaging In 3d (Bio)Printed Models, Ryan Curtis O'Connell

Graduate Theses, Dissertations, and Problem Reports

Electron paramagnetic resonance (EPR), and its molecular imaging modality, is a powerful tool to noninvasively map various biological and chemical markers within objects of interest. Reliable data acquisition is a major impeding factor for longitudinal hands-off measurements. Measurements are especially challenging in biomedical applications, as live objects are not static. Frequent changes occur that require constant fine recalibration of the EPR detection system, called the resonator. To enable longitudinal imaging, a technology permitting automatic digital control of resonator coupling, tuning, and EPR data acquisition was developed. Automation was achieved through the utilization of a microcontroller and digital peripheral components such …

Conducting Polypyrrole Hydrogel Biomaterials For Drug Delivery And Cartilage Tissue Regeneration, Iryna Liubchak

Electronic Thesis and Dissertation Repository

Articular cartilage tissue has limited capacity for self-regeneration leading to challenges in the treatment of joint injuries and diseases such as osteoarthritis. The tissue engineering approach combines biomaterials, cells and bioactive molecules to provide a long-term and stable cartilage repair. In the following work, electroactive polymer polypyrrole~(PPy) was incorporated into the synthetic hydrogel to enhance the mechanical properties of the material for cartilage applications. PPy was loaded with drug compound and the \emph{on demand} drug release was demonstrated. The composite PPy hydrogel was 3D printed using stereolithography to create a porous tissue engineering scaffold. Biocompatibility and cell adhesion to the …

A Novel Electroconductive Nanofibrous Scaffold For Bone Regeneration, Mitchell Kenter

Medical Engineering Theses

The goal of this study was to develop a biodegradable and conductive scaffold to mimic the piezoelectric properties of bone and the architecture of the extracellular matrix. Poly(3,4- ethylenedioxythiophene) (PEDOT) is a conductive polymer of great interest in tissue engineering due to excellent electrical stability and biocompatibility. To enhance its conductivity, dopants such as dimethyl sulfoxide (DMSO) can be added. Engineered graphene oxide (GO) can also be introduced as oxidant to enhance conductivity and mechanical properties. PEDOT nanocomposites were synthesized by oxidative polymerization of 3, 4-Etylenedioxythiophene monomer (EDOT) in the presence of GO, DMSO, ferric chloride and various solvents. The …

3d Printed Polypyrrole Scaffolds For Ph Dependent Drug Delivery With Applications In Bone Regeneration, Matthew T. Lawrence

Electronic Thesis and Dissertation Repository

Areas of large bone loss are typically healed using autologous bone grafts, seen as the gold standard of care. These materials have a complication rate of 10–40% during harvesting and are limited by the quantity available; therefore the use of 3D printed polymer scaffolds as bone graft alternatives are proposed. Polypyrrole (PPy) is a biocompatible electroactive polymer that has metal-like electrical properties that can be harnessed to hold and release charged drug molecules, triggered by a change in pH. pH fluctuations are seen inside the human body in areas of bone regrowth, which would act as the triggering mechanism for …

Flow Visualization Of Bolus Microcapsule Delivery Through 3d Printed Microneedles, Sophie Quisling, Leana Vestal, Alexis Enstrom

Bioengineering Senior Theses

Microneedle arrays are an emerging technology that offers a novel drug delivery system to treat a variety of skin wounds and diseases. The needles deliver therapeutics to the epidermis layer of the skin and therefore establish advantageous qualities over the standard hypodermic needle as they are non-invasive, efficient in biologic absorption, and can be self-administered. This project investigates a custom 3D-printed hollow microneedle device created by a Santa Clara University Senior Design team in 2018 for microencapsulated cell extrusion to be applied for accelerated wound healing. The goal of our project is to operate in the therapeutic range for flowrate …

3d Printable And Computational Models Of The Bone Marrow Mechanical Environment, Alexander Regner

Boise State University Theses and Dissertations

Aged individuals and astronauts experience bone loss despite rigorous physical activity. Bone mechanoresponse is in part regulated by mesenchymal stem cells (MSCs). We reported that daily low intensity vibration (LIV) restores MSC proliferation in senescence and simulated microgravity models, suggesting reduced mechanical signal delivery to MSCs likely contributes to declining bone mechanoresponse. To this end, we have developed a 3D bone marrow analog which controls trabecular geometry, marrow mechanics and external stimuli.

Finite element (FE) models of hydrogels, representing bone marrow, were generated using instantaneous compression (1000% strain/s, 20% strain) and relaxation experiments (100s) of both gelatin and hyaluronin-based hydrogels. …

Quantifying Mafenide Release From 3d Printed Phenylalanine-Coumarin Copolyester Scaffolds, Jacob Seeh

Williams Honors College, Honors Research Projects

This project addressed burn wound healing through controlled release of the antibacterial drug mafenide encapsulated by a copolyster into 3D printed scaffolds. Scaffolds were printed at 25^oC and 0.77-1 bar in a cross-hatch pattern with uniform thickness, distance between parallel layers, and diameter then photo-crosslinked. The number of scaffolds available for testing was limited by the amount of polymer that could be synthesized. A high-performance liquid chromatography method was developed specifically for this experiment and used to determine daily release of mafenide from the scaffold into a 2-mL phosphate buffer solution. During the first 24 hours a large …

Development Of Novel Inks And Approaches For Printing Tissues And Organs, Shen Ji

Dissertations

Tissue engineering is a multidisciplinary field that investigates and develops new methods to repair, regenerate and replace damaged tissues and organs, or to develop biomaterial platforms as in vitro models. Tissue engineering approaches require the fabrication of scaffolds using biomaterials or fabrication of living tissues using cells. As the demands of customized, implantable tissue/organs are increasing and becoming more urgent, conventional scaffold fabrication approaches are difficult to meet the requirements, especially for complex large-scale tissue fabrication. In this regard, three-dimensional (3D) printing attracted more interest over the past decades due to its unrivaled ability to fabricate highly customized tissues or …

Metal Additive Manufacturing For Fixed Dental Prostheses, Mai El Najjar

Electronic Thesis and Dissertation Repository

The use of additive manufacturing (AM) in dentistry has gained momentum in recent years. However, high initial costs and uncertainty surrounding the quality of AM products are considered barriers to their use. This research compared dental substructures fabricated by AM versus conventional casting and milling.

Cobalt-chromium alloy rectangular bars and three-unit bridge substructures were fabricated by AM, casting or milling. Bars manufactured by AM exhibited superior flexural strength, shear bond strength of porcelain coating, and Vickers hardness. Bridge substructures fabricated by AM showed similar flexural stiffness to cast, similar flexural loads at failure to milled and cast, and overall accuracy …

Left Atrial Appendage Printing Process, Areli Reyes, Brandon James Mukai, Mia Noelle Von Knorring

Biomedical Engineering

The left atrial appendage senior design team aims to assist in closing off the left atrial appendage that is susceptible to coagulation due to non-valvular atrial fibrillation. Coagulation in the left atrial appendage (LAA) can be life threatening as it can lead to a stroke. Dr. Chris Porterfield performs a procedure that uses the Boston Scientific Watchman to close the appendage. He finds that sizing the Watchman properly is difficult with limited visuals from live CT scans. He proposed converting the CT scans into a 3D printed model of the left atrial appendage and left atrium so he can visually …

Titanium Nitride Nanotube Electrodes Used In Neural Signal Recording Application And Neurotransmitter Detection, Gui Chen

Wayne State University Dissertations

Electrode probes are devices widely used for stimulating and recording neural cell signals in the neuroscience field, which can convert the ion potential generated by electrochemical activities into an electronic potential that can be measured by the external instrument systems. A stable neural interface that effectively communicates with the nervous system via electrode is much important for the robust recording and the long-term monitoring of the activity of the neural signals. These probes are designed to minimize tissue damage for superior signal quality. Each probe’s mechanical, geometric, and electrical characteristics are precise and highly reproducible for consistent, high-quality results. There …

Binder Saturation, Layer Thickness, Drying Time And Their Effects On Dimensional Tolerance And Density Of Cobalt Chrome - Tricalcium Phosphate Biocomposite, John Ruprecht

All Graduate Theses, Dissertations, and Other Capstone Projects

Traditional metals such as stainless steel, titanium and cobalt chrome are used in biomedical applications (implants, scaffolds, etc.) but suffer from issues such as osseointegration and compatibility with existing bone. One way to improve traditional biomaterials is to incorporate ceramics with these metals so that their mechanical properties can be similar to cortical bones. Tricalcium phosphate is such a ceramic with properties such that it can be used in the human body. This research explores the use of the Binder Jetting based additive manufacturing process to create a novel biocomposite made of cobalt chrome and tricalcium phosphate. Experiments were conducted …

Application Of Halloysite Nanotubes In Bone Disease Remediation And Bone Regeneration, Yangyang Luo

Doctoral Dissertations

Customized patient therapy has been a major research focus in recent years. There are two research fields that have made a significant contribution to realizing individualized-based treatment: targeted drug delivery and three-dimensional (3D) printing technology. With benefit from the advances in nanotechnology and biomaterial science, various drug delivery systems have been established to provide precise control of therapeutic agents release in time and space. The emergence of three-dimensional (3D) printing technology enables the fabrication of complicated structures that effectively mimic native tissues and makes it possible to print patient-specific implants. My dissertation research used a clay nanoparticle, halloysite, to develop …

Fabrication And Characterization Of Collagen-Polypyrrole Constructs Using Direct-Ink Write Additive Manufacturing, Rooshan Arshad

Electronic Thesis and Dissertation Repository

Current efforts in the tissue engineering field are being directed towards the creation of platforms which will facilitate in instructing cells towards biologically relevant outcomes such as stem cell differentiation and disease pathophysiology. Traditional fabrication methods serve as a limiting factor for the production of such platforms as they lack feature and geometric complexity. Additive Manufacturing (AM) offers advantage over said methods by affording designers creative freedom and great control over printed constructs. Such constructs can then be used to create appropriate models for study- ing a plethora of tissues and structures. An AM methodology for Direct-Ink Write (DIW) printing …

3d Printing A Microfluidic Chip Capable Of Droplet Emulsion Using Ninjaflex Filament, Robert Andrews

Mechanical Engineering Undergraduate Honors Theses

This paper details an investigation into methods and designs of 3D printing a microfluidic system capable of droplet emulsion using NinjaFlex filament. The specific field in which this paper’s experiment is rooted is dubbed “BioMEMS,” short for bio microelectromechanical systems. One prominent research area in BioMEMS is developing a “lab on a chip.” Essentially, the goal is to miniaturize common lab processes to the micro scale, rendering it possible to include these processes in a small chip. Reducing necessary sample sizes, shortening the reaction times of lab processes, and increasing mobility of lab processes can all be realized through microfluidic …

Efficacy Of Eluted Antibiotics In 3d Printed Orthopaedic Implants, Mohammed Mehdi Benmassaoud

Theses and Dissertations

Costs associated with musculoskeletal diseases in the United States account for 5.7 % of the Gross Domestic Product (GDP) [1]. As such, there is a need to pursue new ideas in orthopaedic implants that can decrease cost and improve patient care. In the recent years, 3D printing using Fused Deposition Modeling (FDM) or Stereolithography (SLA) has opened several exciting possibilities to create orthopaedic implants. Such implants can be engineered to release antibiotics in a controlled manner either by infusing the drug into the material during manufacturing or by using built-in design features such as micro-channels and reservoirs [2]. The use …

Developmental Steps For A Functional Three-Dimensional Cell Culture System For The Study Of Asymmetrical Division Of Neural Stem Cells, Martina Zamponi

Biomedical Engineering Theses & Dissertations

Stem cells are a cell type present during and following development, which possess self- renewal properties, as well as the ability to differentiate into specific cells. Asymmetrical division is the cellular process that allows stem cells to produce one differentiated and one un-differentiated daughter cell during the same mitotic event. Insights in the molecular mechanisms of such process are minimal, due to the absence of effective methods for its targeted study. Currently, traditional methods of investigation include monolayer cell culture and animal models. The first poses structural limitations to the accurate representation of human tissue and cell structures, while animal …

Osteon Mimetic Scaffolding, Janay Clytus

Senior Theses

The purpose of this research is to provide an alternative to naturally derived bone grafts. There is a gap in the supply of donors and the demand of bone tissue. Artificial scaffold creation can work as an implant and decrease the shortage of bone grafts and increase the range of injuries that can be repaired. Current research focuses on optimizing mechanical properties such as porosity, improving vascularization using cells, and generating osteoconductivity. For osteodifferentiation, mesenchymal stem cells (MSCs) can differentiate into mesodermal lineages such as chondrocytes, osteoblasts, adipocytes, and tenocytes by supplementing cultures with lineage-specific soluble factors (Marchetti). Co-culturing ECFCs …

A Patient-Specific Cardiac Phantom For Training And Pre-Procedure Surgical Planning, Justin Laing

Electronic Thesis and Dissertation Repository

Minimally invasive cardiac procedures requiring a transseptal puncture are becoming increasingly common. For cases of complex or diseased anatomy, clinicians may benefit from using a patient-specific cardiac phantom for training, surgical planning, and the validation of devices or techniques.

An imaging compatible cardiac phantom was developed to simulate a MitraClip ® procedure. The phantom contained a patient-specific cardiac model manufactured using tissue mimicking materials.

To evaluate accuracy, the patient-specific model was imaged using CT, segmented, and the resulting point cloud data set was compared using absolute distance to the original patient data. The phantom was validated using a MitraClip ® …

An Automated Device To Increase Screening Throughput Of Zebrafish Larvae, Fuoad Saliou-Sulley

Electronic Theses and Dissertations

The use of the zebrafish as an animal model alternative to mammalian species has spawned research advancements in several medical fields. Since the zebrafish shares a high degree of sequence and functional homology with mammals, studies using this organism can provide in-depth insight into host response to disease and provide a platform for testing a range of treatment options. The optical transparency of zebrafish at early stages of development permits easy assessment of the effects of treatments, occurrence of tumors and other abnormal growth, disease progression, and immune response, to name only a few. These characteristics make it ideal for …

Fluid Flow Characterization And In Silico Validation In A Rapid Prototyped Abdominal Aortic Aneurysm Model, Dean Thomas Wampler

Master's Theses

Aortic aneurysms are the 14^th leading cause of death in the United States. Annually, abdominal aortic aneurysm (AAA) ruptures are responsible for 4500 deaths. There are another 45,000 repair procedures performed to prevent rupture, and of these approximately 1400 lead to deaths. With proper detection, the aneurysm may be treated using endovascular aneurysm repair (EVAR). Understanding how the flow of the blood within the artery is affected by the aneurysm is important in determining the growth of the aneurysm, as well as how to properly treat the aneurysm. The goal of this project was to develop a physical construct …

Development Of An Electrospun And 3d Printed Cellular Delivery Device For Dermal Wound Healing, Ryan M. Clohessy

Theses and Dissertations

The goal of this research was to develop a system of individualized medicine that could be applied to dermal wounds serving as a wound dressing and synthetic extracellular matrix while delivering stem cells to the wound bed. First, fabrication parameters for electrospinning polymer fibers were determined. This involved evaluating fiber morphology with respect to polymer selection and solution concentration. Next, construct fabrication was examined to produce an integrated void space, or cargo area, suitable to maintain stem cells. In vitro studies to ensure stem cell viability and phenotype were conducted, and results supported the notion that cells could be administered …

A Multi-Channel 3d-Printed Bioreactor For Evaluation Of Growth And Production In The Microalga Dunaliella Sp, Cristian A. Cox

Electronic Theses and Dissertations

We explored the capabilities of additive manufacturing using a photo-cured jetted material 3D printer to manufacture a milli-microfluidic device with direct application in microalgae Dunaliella sp growth and intracellular compounds biosynthesis tests. A continuous microbioreactor for microalgae culture was CAD designed and successfully built in 1 hour and 49 minutes using black photopolymer cured by UV and a support material. The microreactor was made up of 2 parts including the bioreactor itself and a microchannel network for culture media fluids and microalgae. Both parts were assembled to form a single unit. Additional optical and auxiliar components were added. An external …

Fluid Flow Characterization And In Silico Validation In A Rapid Prototyped Aortic Arch Model, Alexandra Mariel Knauer

Master's Theses

Transcatheter aortic heart valve replacement (TAVR) is a procedure to replace a failing aortic valve and is becoming the new standard of care for patients that are not candidates for open-heart surgery [2]. However, this minimally invasive technique has shown to cause ischemic brain lesions, or “silent infarcts”, in 90% of TAVR patients, which can increase the patient’s risk for stroke by two to four times in future years [3]. Claret Medical Inc., a medical device company, has developed a cerebral protection system that filters and captures embolic debris released during endovascular procedures, such as TAVR. This thesis utilized CT …

Healing Of Bone Defects In A Rodent Calvarial Defect Model Using Strong Porous Bioactive Glass (13-93) Scaffolds, Yinan Lin

Masters Theses

"The main objective of this project was to evaluate the capacity of strong porous silicate (13-93) bioactive glass scaffolds prepared by a robocasting technique to regenerate bone and stimulate angiogenesis in a rat calvarial defect model. The scaffolds were created with the same grid-like microstructure but in a variety of formulations: (i) as-fabricated, (ii) pretreated in an aqueous phosphate solution to convert the glass surface to hydroxyapatite, (iii) loaded with bone morphogenetic protein-2 (BMP2) (1 µg per scaffold), and (iv) doped with copper (0.4-2.0 wt. % CuO). When compared to the as-fabricated scaffolds, the pretreated scaffolds enhanced bone regeneration at …

Nanotechnology And Additive Manufacturing Platforms For Clinical Medicine: An Investigation Of 3d Printing Bioactive Constructs And Halloysite Nanotubes For Drug Delivery And Biomaterials, Jeffery A. Weisman

Doctoral Dissertations

Personalized medicine requires the development of new technologies for controlled or targeted drug delivery. Three-dimensional (3D) printing and additive manufacturing techniques can be used to generate customized constructs for bioactive compound delivery. Nanotechnology in the form of nanoparticles, used as a stand-alone construct or for material enhancements, can significantly improve established biomaterials such as PMMA based bone cements or enable new technology to have enhanced capabilities. Combinations of the technologies can be used in such applications as infectious disease treatments, chemotherapeutic targeted drug delivery or targeted delivery of nearly any bioactive compound.

Chemotherapeutic or antibiotic enhanced 3D printing filaments were …