Theses and Dissertations at Montana State University (MSU)
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Item Colloids, diagnostics, and 3D-printed hydrogels(Montana State University - Bozeman, College of Engineering, 2021) LeFevre, Thomas Brian; Chairperson, Graduate Committee: James Wilking; This is a manuscript style paper that includes co-authored chapters.Colloidal suspensions are dispersions of microscopic particles in liquid. Their properties have broad impacts in industry, medicine, and biology. In Chapter 2, we focus on measuring the interactions between colloidal particles suspended in water and a glass surface. We measure these interactions using a custom-built fluorescence centrifuge force microscope (F-CFM). This is the first CFM built with fluorescence capability, the first CFM used to measure colloidal interaction forces, and the first CFM capable of operating at speeds above 2000 RPM - and up to 5000 RPM - in a centrifuge. The F-CFM enables colloidal scale objects to be discriminated by fluorescence, which opens potential applications for biological samples that fluoresce under different phenotypic states. In Chapter 3, we focus on designing a point-of-care (POC) saliva collection, metering, and mixing system for detecting viral pathogens. The device was designed for the specific purpose of testing for the presence of SARS-CoV-2 in saliva using molecular amplification methods but could be applied to any pathogen whose constituents can be detected in saliva. The design to prioritizes ease of use, low cost, and scalability in order to facilitate massively widespread testing, which was absent during the first years since the emergence of SARS-CoV-2, In Chapter 4, we describe a method of formulating and printing hydrogel resins with high resolution channels using light-based 3D printing. In Chapter 5, we describe a leak-resistant, pressurized connector platform for connecting modular hydrogels that can be used to create complex assemblies of hydrogel components. In Chapter 6, we describe a microscope sample temperature control platform that fits into standard upright microscope stages in order to heat and cool samples in a controlled manner under the microscope in order to observe temperature dependent reactions like polymerase chain reaction (PCR) and loop-mediated isothermal amplification (LAMP). In Chapter 7, we describe a LAMP formulation that can be used to detect the presence of SARS-CoV-2 RNA in saliva despite the inhibitory components present in saliva and demonstrate its comparable accuracy to the gold standard of pathogenic testing: nasopharyngeal PCR testing.Item Predicting and modeling the material properties of fused deposition modeling elements leading to more efficient structural designs(Montana State University - Bozeman, College of Engineering, 2021) Murray, Flynn Rae; Chairperson, Graduate Committee: Michael BerryThe current construction industry has a significant negative impact on the climate, and this impact is expected to increase as the world's population continues to grow and urbanization expands. This impact may be reduced by implementing more sustainable building materials and practices. The primary objective of this research is to develop a methodology to estimate and model the material/structural response of elements made with fused deposition modeling. This will ultimately lead to an increased use of FDM in structural applications, and open the door to combining FDM with topology optimization to design and build optimized structural elements, resulting in a more sustainable infrastructure. In this research, tensile and flexural specimens printed in a variety of orientations were tested to evaluate/quantify the effects that print orientation have on elastic properties, ultimate stresses, and failure mechanisms of FDM parts. These elastic properties were then implemented into an orthotropic formulation of the Generalized Hooke's Law, and successfully used in finite element models to predict the elastic response of FDM specimens. Based on this analysis, it was determined that, while the Generalized Hooke's Law provided some advantages, the elastic material response of FDM parts could be estimated with a simpler isotropic model with little loss of accuracy. Response Surface Methodology (RSM) was then successfully used to further evaluate/quantify the effects that print orientation and scale have on the behavior of FDM parts, and to develop equations to predict the stiffness and strength of FDM parts given these print parameters. Finally, the feasibility of using topology optimization combined with additive manufacturing is briefly investigated.Item Improving transport in hydrogels for 3D bioprinting applications(Montana State University - Bozeman, College of Engineering, 2021) Abbasi, Reha; Chairperson, Graduate Committee: James Wilking; Aaron D. Benjamin was an author and Madison Owens, Robert J. Olsen, Danica J. Walsh, Thomas B. LeFevre and James N. Wilking were co-authors of the article, 'Light-based 3D printing of hydrogels with high-resolution channels' in the journal 'Biomedical physics & engineering express' which is contained within this dissertation.; Thomas B. LeFevre was an author and Aaron D. Benjamin, Isaak J. Thornton, and James N. Wilking were co-authors of the article, 'Coupling fluid flow to hydrogel fluidic devices with reversible "pop-it" connections' in the journal 'Lab on a chip' which is contained within this dissertation.; Zahra Mahdieh was an author and Galip Yiyen, Robert A. Walker and James N. Wilking were co-authors of the article, 'Light-based 3D bioprinting of hydrogels containing colloidal calcium peroxide' submitted to the journal 'Bioprinting' which is contained within this dissertation.Hydrogels are soft, water-based gels with widespread applications in medicine, tissue engineering, and biotechnology. Many of these applications require structuring hydrogels in three-dimensional space. Light-based 3D printers offer exquisite spatial control; however, technologies for light-based 3D-printing of hydrogels remain limited. This is mainly caused by poor material transportation through the hydrogel. For example, limited transport of oxygen and other nutrients through 3D printed tissue constructs containing living cells leads to low cell viability. Here, we describe three experimental research studies focused on improving material transport in 3D-printed hydrogels. In the first part of this thesis, we describe a generalizable method for light-based 3D printing of hydrogels containing open, well-defined, submillimeter-scale channels with any orientation. These submillimeter channels allow for bulk liquid flow through the hydrogel to improve nutrient and oxygen transport. In the second part of this thesis, we describe a simple, reversible, plug-based connector designed to couple tubing to a hydrogel-based fluidic device to allow for pressurized liquid flow through the system. The resulting connection can withstand liquid pressures significantly greater than traditional, connector-free approaches, enabling long-term flow through 3D-printed hydrogels. In the third part of this thesis, we characterize the printability of photopolymerizable resins containing particles that slowly dissolve to release oxygen and thereby improve cell viability. The light-based 3D bioprinting technologies we describe in this thesis will improve material transport through 3D printed hydrogels and enable a wide variety of applications in 3D bioprinting and hydrogel fluidics.