OBJECTIVE: To assess the effect of denture cleansers on the mechanical and optical properties such as color stability, surface hardness, surface roughness, and flexural strength of the 3D printed denture acrylics in comparison to heat polymerized denture acrylics. MATERIALS AND METHODS: A total of 216 disc specimens (12 mm × 2mm) were made from Lucitone Digital Print, DENTCA Denture Base II, Formlabs denture resin, and Lucitone 199. Each type of acrylic was divided into four sub-groups, Efferdent, Polident, dish soap and control group in water. Specimens of each material were exposed to a total of 28 cycles of immersion in denture cleanser, while being stored in water in an incubator at 37°C in between cycles to test for color stability, surface roughness, microhardness and biaxial flexural strength. Baseline values were obtained for color, hardness, surface roughness, and biaxial flexural strength using a CIE L*a*b* color space by spectrophotometer, Vickers microhardness in hardness tester, line Ra by profilometer, and ball-on-three-ball fixture with universal testing machine respectively. Color, surface roughness, and surface hardness values were obtained at the 8th, 16th, and 28th cycles in order to compare color stability along with changes in surface roughness and surface hardness. Biaxial flexural strength values were performed for specimens at the 28th cycle as a destructive test to compare values of treated and untreated specimens. SEM analysis was performed to assess fracture behavior and microstructural changes. The differences between the tested materials and the treatment effects were statistically analyzed using the Tukey HSD test (a=0.05) and MANOVA test (a=0.05) RESULTS: The greatest significant change in color was seen in Lucitone 199 specimens (P value <0.0001) when exposed to dish soap. Lucitone 199 and Lucitone Digital Print had the significantly lowest microhardness values (P value< 0.0001) after exposure to treatments, especially dish soap. Surface roughness was significantly higher for all 3D specimens initially (P value <0.001), however with exposure to Efferdent and Polident, Lucitone 199 specimens had the greatest significant increase in surface roughness. The surface roughness of 3D printed specimens did not significantly increase with exposure to treatments. The biaxial flexural strength of all materials decreased significantly with the exposure to all treatments (P value< 0.0001). Overall, Lucitone 199 had the lowest flexural strength in both treatment and control groups compared to all the 3D printed materials. Formlabs was significantly affected by exposure to treatments,and had the greatest decrease in biaxial flexural strength (P value <0.0001). CONCLUSION: Within the limitations of this study, we can conclude that 3D printed materials in this study are more color stable that the heat-polymerized Lucitone 199. In regards to microhardness, 3D printed materials except for Lucitone Digital Print have higher microhardness values than heat-polymerized materials. Although Lucitone 199 had a smoother surface as prepared, the 3D printed materials in this study maintained their roughness values throughout the study, whereas Lucitone 199 showed a significant increase in roughness. The properties of 3D printed materials show a promising future for their use in treating edentulous patients. Although there are limitations to this study, it is safe to say that denture cleansers are safe to use with 3D printed dentures as long as the manufacturer’s instructions are correctly followed.

This master thesis summarizes the current knowledge about non-commercial 3D printing FDM technology. The goal of this thesis is to demonstrate the gained knowledge by building a 3D printer which can partially replicate itself, and to evaluate its technological parameters. The experimental part of this work is focused on the impact of the changes in technological parameters of printing on mechanical properties of printed parts.

This thesis deals with design and productions of low-cost robot used for presentation and marketing purposes of companies CUTTER Systems spol. s r.o. and N-ROTE Mechanical s r.o. The main task of this robot is to serve beverages into glass containers.

Increased interest in and use of additive manufacturing has made it an important component of advanced manufacturing in the last decade. Material Extrusion Additive Manufacturing (MatEx) has seen a shift from a rapid prototyping method harnessed only in parts of industry due to machine costs, to something widely available and employed at the consumer level, for hobbyists and craftspeople, and industrial level, because falling machine costs have simplified investment decisions. At the same time MatEx systems have been scaled up in size from desktop scale Fused Filament Fabrication (FFF) systems to room scale Big Area Additive Manufacturing (BAAM). Today MatEx is still used for rapid prototyping, but it has also found application in molds for fiber layup processes up to the scale of wind turbine blades. Despite this expansion in interest and use, MatEx continues to be held back by poor part performance, relative to more traditional methods such as injection molding, and lack of reliability and user expertise. In this dissertation, a previously unreported phenomenon, irreversible thermal strain (ITε), is described and explored. Understanding ITε improves our understanding of MatEx and allows for tighter dimensional control of parts over time (each of which speaks to extant challenges in MatEx adoption). It was found that ITε occurs in multiple materials: ABS, an amorphous polymer, and PLA, a semi-crystalline one, suggesting a number of polymers may exhibit it. Control over ITε was achieved by tying its magnitude back to part layer thickness and its directionality to the direction of roads within parts. This was explained in a detail by a micromechanical model for MatEx described in this document. The model also allows for better description of stress-strain response in MatEx parts broadly. Expanding MatEx into new areas, one-way shape memory in a commodity thermoplastic, ABS, was shown. Thermal history of polymers heavily influences their performance and MatEx thermal histories are difficult to measure experimentally. To this end, a finite element model of heat transfer in the part during a MatEx build was developed and validated against experimental data for a simple geometry. The application of the model to more complex geometries was also shown. Print speed was predicted to have little impact on bonds within parts, consistent with work in the literature. Thermal diffusivity was also predicted to have a small impact, though larger than print speed. Comparisons of FFF and BAAM demonstrated that, while the processes are similar, the size scale difference changes how they respond to process parameter and material property changes, such as print speed or thermal diffusivity, with FFF having a larger response to thermal diffusivity and a smaller response to print speed. From this experimental and simulation work, understanding of MatEx has been improved. New applications have been shown and rational design of both MatEx processes and materials for MatEx has been enabled.

Introduction: Gram-negative prosthetic joint infections (GN-PJI) present unique challenges in management due to their distinct pathogenesis of biofilm formation on implant surfaces. The purpose of this study is to establish a clinically representative GN-PJI model that can reliably recapitulate biofilm formation on titanium implant surface in vivo. I hypothesized that biofilm formation on an implant surface will affect its ability to osseointegrate. Methods: The model was developed using 3D-printed titanium hip implants, to replace the femoral head of male Sprague-Dawley rats using a posterior surgical approach. GN-PJI was induced using two bioluminescent Pseudomonas aeruginosa (PA) strains: a reference strain (PA14-lux) and a mutant strain that is defective in biofilm formation (flgK-lux). Infection was assessed in real-time using the in vivo imaging system (IVIS) and Magnetic Resonance Imaging (MRI) and in vitro by quantifying bacterial loads on collected implants surface and in periprosthetic tissues as well as biofilm visualization using the Field emission scanning electron microscopy (FE-SEM). The implant stability, as an outcome, was directly assessed by quantifying the osseointegration in vitro using microCT scan, and indirectly assessed by identifying the gait pattern changes using DigiGaitTM system in vivo. Results: Bioluminescence detected by IVIS, was focused on the hip region, demonstrating localized-infection, with the ability of PA14-lux to persist in the model compared to flgK-lux defective in biofilm formation. This was corroborated by MRI as the PA14-lux induced relatively larger implant-related abscesses. Biofilm formation at the bone-implant-interface induced by the PA14-lux was visualized using FE-SEM versus defective-biofilm formation by flgK-lux. This could be quantitatively confirmed, by average viable-colony-count of the sonicated implants, 3.77x108CFU/ml versus 3.65x103CFU/ml for PA14-lux and flgK-lux, respectively (p=0.0025; 95%CI: -6.08x108 to -1.45x108). This difference in the ability to persist in the model was reflected significantly on the implant osseointegration with a mean intersection surface 4.1x106μm2 1.99x106 for PA14-lux versus 6.44x106μm2 2.53x106 for flgK-lux and 7.08x106μm2 1.55x106 for non-infected control (p=0.048). Conclusions: To date, the proposed in vivo biofilm-based model is the most clinically representative for GN-PJI since animals can bear weight on the implant and poor osseointegration correlates with biofilm formation. Clinical Relevance: The current model will allow for reliable testing of novel biofilm-targeting therapeutics.

Preterm birth (PTB) is defined as birth before the 37th week of pregnancy and affects 15 million infants per year. Presently, there is no clinical test to determine PTB risk. A 3D printed microfluidic device is being developed as a clinical test for PTB risk via detection of a panel of biomarkers. A significant step is extraction of the PTB biomarkers from blood serum. In this work, I developed 3D printed microfluidic devices in which monoliths can be polymerized. Using the monolith as a solid support to attach antibody, I show that ferritin, one of the PTB biomarkers, can be selectively extracted from human blood serum. This is the first study where a monolith has been formed in a 3D printed microfluidic device and used to perform an immunoaffinity extraction. This work is an important step in developing a clinical test for PTB risk. The realization of this work also demonstrates that 3D printing can be used to fabricate functional microfluidic devices.

No description available.

3D printing for microfluidic device fabrication has received considerable interest in recent years, in part driven by the potential to dramatically speed up device development by reducing device fabrication time to the minutes timescale. Moreover, in contrast to traditional cleanroom-based fabrication processes that require manual production and stacking of a limited number of layers, 3D printing allows full use of the 3D fabrication volume to lay out microfluidic elements with complex yet compact 3D geometries. The Nordin group has successfully developed multiple generations of high resolution printers and materials for microfluidic devices that achieve this vision. However, because of the customizability of design in the Nordin microfluidics lab, finding settings that lead to a successful print can involve a taxing cycle of adjustments. The current 3D microfluidics design flow, which requires each student to find settings for each design, makes it difficult for new students to rapidly print successful designs with new components. In this thesis I present an Improved Microfluidic Design Approach (IMDA) that is based on a pre-defined component library. It allows students to reuse a library of components such that a new designer can utilize the work of more experienced predecessors, allowing the lab to avoid repeating the same parameter tuning process with each student. So far the tool has shown the feasibility of printing new designs based on previously tested components. Ultimately, my work demonstrates an attractive path to make the 3D printed microfluidic design experience more robust, repeatable, and easier for newcomers to learn.

No description available.

While 3D printing technologies first appeared in the 1980s, prohibitive costs, limited materials, and the relatively small number of commercially available printers confined applications mainly to prototyping for manufacturing purposes. As technologies, printer cost, materials, and accessibility continue to improve, 3D printing has found widespread implementation in research and development in many disciplines due to ease-of-use and relatively fast design-to-object workflow. Several 3D printing techniques have been used to prepare devices such as milli- and microfluidic flow cells for analyses of cells and biomolecules as well as interfaces that enable bioanalytical measurements using cellphones. This review focuses on preparation and applications of 3D-printed bioanalytical devices.