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Full-Text Articles in Engineering

Conducting Polypyrrole Hydrogel Biomaterials For Drug Delivery And Cartilage Tissue Regeneration, Iryna Liubchak Aug 2022

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 …


3d Printing Technology Applied In Lithium Metal Batteries: From Liquid To Solid., Xuejie Gao Aug 2021

3d Printing Technology Applied In Lithium Metal Batteries: From Liquid To Solid., Xuejie Gao

Electronic Thesis and Dissertation Repository

Li-metal batteries are strongly considered to be one of the most promising candidates for high energy density energy storage devices in our modern society. However, the state-of-the-art Limetal batteries are still limited by several challenges including 1) low energy/power density; 2) Li dendrite growth; 3) low coulombic efficiency, and 4) safety concerns within the liquid electrolyte. This thesis mainly focuses on addressing these challenges by using a 3D printing technique to realize high energy/power density Li-metal batteries.

A self-standing high areal energy density cathode for Li-S battery was developed by the 3D printing method in the first part. The optimized …


3d Printed Polypyrrole Scaffolds For Ph Dependent Drug Delivery With Applications In Bone Regeneration, Matthew T. Lawrence Jun 2021

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 …


Study Of Recyclable And Repairable Dynamic Covalent Polymers For Sustainable 3d Printing Development, Mingyue Zheng Feb 2021

Study Of Recyclable And Repairable Dynamic Covalent Polymers For Sustainable 3d Printing Development, Mingyue Zheng

Electronic Thesis and Dissertation Repository

3D printing technology with valuable features, including cost-saving, easy access, and unlimited structure design, has attracted significant attention and been employed for production use. This technology has also been considered as a sustainable manufacturing method and quickly developed in recent years. However, the development of sustainable 3D printing is still facing challenges, especially in waste management. Thanks to the flexibility of 3D printing and diversified printing mechanisms, the big step forward can be approachable by the transformation from materials. This dissertation presents a variety of strategies designed for sustainable 3D printing development based on the combination of dynamic covalent chemistry …


Metallization Process For 3d Printed Electronics: From I3dp Ii To 3d Co-Printing Technology, Junfeng Xiao Feb 2021

Metallization Process For 3d Printed Electronics: From I3dp Ii To 3d Co-Printing Technology, Junfeng Xiao

Electronic Thesis and Dissertation Repository

3D printing has emerged as a powerful additive manufacturing technique and becomes as a viable alternative to conventional manufacturing processes in an increasing number of applications. Thus, the development of printable materials also continues to expand, while polymers are still the most utilized materials in 3D printing. There is a great advance for developing polymers with versatile mechanical and chemical properties. However, the end-use products are demanding various functions. It is imperative to develop functional 3D printed polymeric materials to achieve enhanced functionalities.

Usually, one polymer can meet one specific application. This has considerably limited the capability of 3D printing …


Rational Design Of Cell Configurations For High-Performance Na-O2 Batteries, Xiaoting Lin Aug 2020

Rational Design Of Cell Configurations For High-Performance Na-O2 Batteries, Xiaoting Lin

Electronic Thesis and Dissertation Repository

Na-O2 batteries are considered as the promising candidates for electric vehicles due to their ultrahigh theoretical energy densities. However, state-of-the-art Na-O2 batteries suffer from serious challenges including 1) pore clogging and insufficient O2 transportation within the air electrode; 2) degradation of air electrode, 3) Na dendrite growth; and 4) Na corrosion induced by O2/O2- crossover. This thesis, therefore, focuses on rational design of cell configurations to address these problems and understanding the insight mechanisms.

3D printing of “O2 breathable” air electrodes for Na-O2 batteries were first developed. The unique air electrode …


Effects Of Corner Radii On Wind Tunnel Testing Of Low-Rise Buildings, Kytin Kwan Jul 2020

Effects Of Corner Radii On Wind Tunnel Testing Of Low-Rise Buildings, Kytin Kwan

Electronic Thesis and Dissertation Repository

Wind effects on buildings are commonly studied by testing 3D printed building models in a wind tunnel. A challenge with 3D printing is that the edges of these models may not be perfectly sharp, but rounded with a radius of curvature, R. It is well known that when edges are significantly rounded, the aerodynamics of the building can be altered (Robertson, 1991; Mahmood 2011), leading to inaccurate predictions of full-scale surface pressures and wind loads. However, there is presently no guidance on model edge radii prescribed in wind tunnel testing standards such as ASCE 49-12. The objective of the present …


Metal Additive Manufacturing For Fixed Dental Prostheses, Mai El Najjar Jun 2020

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 …


Fabrication And Characterization Of Collagen-Polypyrrole Constructs Using Direct-Ink Write Additive Manufacturing, Rooshan Arshad May 2019

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 …


Fabrication Of 3d Conjugated Polymer Structures Via Vat Polymerization Additive Manufacturing, Andrew T. Cullen Apr 2018

Fabrication Of 3d Conjugated Polymer Structures Via Vat Polymerization Additive Manufacturing, Andrew T. Cullen

Electronic Thesis and Dissertation Repository

Conjugated polymers are a class of electromechanically active materials that can produce motion in response to an electric potential. This motion can be harnessed to perform mechanical work, and therefore these materials are particularly well suited for use as sensors and actuators in microelectromechanical systems. Conventional methods to fabricate conjugated polymer actuators result in planar morphologies that limit fabricated devices to simplistic linear or bending actuation modes. To overcome this limitation, this work develops a conjugated polymer formulation and associated additive manufacturing method capable of realizing three-dimensional conductive polymer structures. A light-based additive manufacturing technique known as vat polymerization is …


A Patient-Specific Cardiac Phantom For Training And Pre-Procedure Surgical Planning, Justin Laing Oct 2017

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 ® …