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The ability to generate a range of concentrations of various solutions rapidly and conveniently is an ongoing need in biotechnology. In this thesis we demonstrate how we took advantage of the full process control afforded by our recent custom high resolution 3D printer and resin advances to realize highly integrated and miniaturized microfluidic components for simultaneous on-chip serial dilution for dose-response assays. With judicious selection of mixed layer thicknesses and pixel-by-pixel dose control, we show that the diameter of 3D printed membrane valves can be reduced from 300 µm to 46 µm. We further introduce an entirely new kind of 3D printed valve, termed a squeeze valve, in which the active area is reduced still further to 15 µm x 15 µm. We demonstrate and characterize pumps based on each type of valve and introduce a short (<1 mm long) high aspect ratio channel that enables rapid diffusion-based mixing. We show that combining two pumps with this diffusion mixing channel results in a highly compact 1:1 mixer component. Connecting 10 of these components in series yields a miniature 10 stage 2-fold microfluidic serial dilution module that from two solution inputs simultaneously generates 10 output concentrations that cover three orders of magnitude. We show the efficacy of our serial dilution approach by demonstrating an assay for dose-dependent permeabilization of A549 cells in different concentrations of digitonin integrated into a single device. Our demonstration of component miniaturization in conjunction with a high degree of integration illustrates the promise of 3D printing to enable highly functional and compact microfluidic devices for a variety of biomolecular applications.

The aim of my diploma thesis was engineering design of 4x4 chassis dynamometer model at 1:10 scale for presentation purpose and for testing RC cars models. The first part describes the current types of chassis dynamometers. The main goal of the thesis was designed the model itself in order to produce some parts of the dynamometer using 3D printing. The work also includes production drawings of individual parts and economic estimate of the entire production.

This work is focused on solving the problems of delta 3d printer frame rigidity and impact of rigidity on final quality of 3d printing. A variant of a 3d printer on a classic Kossel-shaped frame has designed and built. Further, frame strength analysis and improvement design is performed, with subsequent production of a new variant and comparison of the 3d printing results of both variants. The result of this work is to show how the frame construction really affects the print quality.

This thesis deals with properties of austenitic stainless steel 304L processed by SLM technology and tested at room and cryogenics temperatures. Result is description of mechanical properties and microstructure. First step was to develop processing parameters to achieve porosity of prints fell below 0,01 %. Following tensile test showed higher yield and ultimate tensile strength than conventionally fabricated parts, even at temperature -80 °C, but at cost of reduced ductility. Due to deformation and low temperature austenite transformed into martensite. This transformation also occurred in Charpy toughness test, that resulted in ductile to brittle behaviour.

Sandwich panels serve many purposes in engineering applications. Additive manufacturing opened the door for easy fabrication of the sandwich panels with different core structures. In this study, additive manufacturing technique, experiments, and numerical analysis are combined to evaluate the mechanical properties of sandwich panels with different cellular core structures. The sandwich panels having honeycomb, re-entrant honeycomb, diamond, square core topologies are printed with the vat photopolymerization technique. Uniaxial compression testing is performed to determine the compressive modulus, strength, and specific strength of these lightweight panels. Elasto-plastic finite element analysis having good similarities with the experimental results provided a preview of the stress distribution of the sandwich panels under applied loading. The imaging of the tested samples showed the fractured regions of the cellular cores. Dynamic mechanical analysis of the panels provided scope to compare the performance of panels and solid materials with the variation of temperature. Sandwich panels with the diamond structure exhibit better compressive properties and specific strength while the re-entrant structure offers high energy absorption capacity. The sandwich structures provided better thermo-mechanical properties than the solid material. The findings of this study offer insights into the mechanical properties of sandwich panels printed with vat photopolymerization technique which can benefit a wide range of engineering applications.

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.