Consumer additive manufacturing (3D printing) has rapidly grown over the last decade. While the technology for the most common type, Fused Filament Fabrication (FFF), has systematically improved and sales have increased, fundamentally, the capabilities of the machines have remained the same. FFF printers are still limited to depositing layers onto a flat build plate. This makes it difficult to combine consumer AM with other objects. While consumer AM promises to allow us to customize our world, the reality has fallen short. The ability to directly modify existing objects presents numerous possibilities to the consumer: personalization, adding functionality, improving functionality, repair, and novel multi-material manufacturing processes. Indeed, similar goals for industrial manufacturing drove the research and development of technologies like direct write and directed energy deposition which can deposit layers onto uneven surfaces. Replicating these capabilities on consumer 3-axis FFF machines is difficult mainly due to issues with reliability, repeatability, and quality. This thesis proposes, demonstrates, and tests a method for scanning and printing dimensionally-accurate (unwarped) digital forms onto physical objects using a modified consumer-grade 3D printer. It then provides an analysis of the machine design considerations and critical process parameters. / Master of Science / Consumer additive manufacturing (3D printing) has rapidly grown over the last decade. While the technology for the most common type, Fused Filament Fabrication (FFF), has systematically improved and sales have increased, fundamentally, the capabilities of the machines have remained the same. FFF printers are still limited to depositing layers onto a flat build plate. This makes it difficult to combine consumer AM with other objects. While consumer AM promises to allow us to customize our world, the reality has fallen short. The ability to directly modify existing objects presents numerous possibilities to the consumer: personalization, adding functionality, improving functionality, repair, and novel multi-material manufacturing processes. Indeed, similar goals for industrial manufacturing drove the research and development of technologies like direct write and directed energy deposition which can deposit layers onto uneven surfaces. Replicating these capabilities on consumer 3-axis FFF machines is difficult mainly due to issues with reliability, repeatability, and quality. This thesis proposes, demonstrates, and tests a method for scanning and printing dimensionally-accurate (unwarped) digital forms onto physical objects using a modified consumer-grade 3D printer. It then provides an analysis of the machine design considerations and critical process parameters.

Additive manufacturing in the form of 3D printing is a revolutionary technology that has developed within the last two decades. Its ability to print an object with accurate features down to the micro scale have made its use in medical devices and research feasible. A range of life-saving technologies can now go from the laboratory and into field with the application of 3D-printing. This technology can be applied to medical diagnosis of patients in at-risk populations. Living biosensors are limited by being Genetically Modified Organisms (GMOs) from being employed for medical diagnosis. However, by containing them within a 3D-printed enclosure, these technologies can serve as a vehicle to translate life-saving diagnosis technologies from the laboratory and into the field where the lower cost would allow more people to benefit from inexpensive diagnosis. Also, the GMO biosensors would be contained with a press-fit, ensuring that the living biosensors are unable to escape into the environment without user input. In addition, 3D-printing can also be applied to reduce the cost of lab-based technologies. Cell patterning technology is a target of interest for applying more cost-effective technologies, as elucidation of the variables defining cell patterning and motility may help explain the mechanics of cancer and other diseases. Through the use of a 3D-printed stamp, bacterial cells can be patterning without the use of a clean room, thus lowering the entry-barrier for researchers to explore cell patterning. With the commercialization of 3D-printing an opportunity has arisen to transition life-saving technologies into more cost-effective versions of existing technologies. This would not only allow more research into existing fields, but also to ensure that potentially life-saving technologies reach the people that need them. / Ph. D.

This work created a manufacturing process and material system based on binder jetting Additive Manufacturing to process pure copper. In order to reduce the sintered part porosity and shape distortion during sintering, the powder bed voids were filled with smaller particles to improve the powder packing density. Through the investigation of a bimodal particle size powder bed and nanoparticle binders, this work aims to develop an understanding of (i) the relationship between printed part properties and powder bed particle size distribution, and (ii) the binder-powder interaction and printed primitive formation in binder jetting of metals. Bimodal powder mixtures created by mixing a coarse powder with a finer powder were investigated. Compared to the parts printed with the monosized fine powder constituent, the use of a bimodal powder mixture improved the powder flowability and packing density, and therefore increased the green part density (8.2%), reduced the sintering shrinkage (6.4%), and increased the sintered density (4.0%). The deposition of nanoparticles to the powder bed voids was achieved by three different metal binders: (i) a nanoparticles suspension in an existing organic binder, (ii) an inorganic nanosuspension, and (iii) a Metal-Organic-Decomposition ink. The use of nanoparticle binders improved the green part density and reduced the sintering shrinkage, which has led to an improved sintered density when high binder saturation ratios were used. A new binding mechanism based on sintering the jetted metal nanoparticles was demonstrated to be capable of (i) providing a permanent bonding for powders to improve the printed part structural integrity, and (ii) eliminating the need for organic adhesives to improve the printed part purity. Finally, the binder-powder interaction was studied by an experimental approach based on sessile drop goniometry on a powder bed. The dynamic contact angle of binder wetting capillary pores was calculated based on the binder penetration time, and used to describe the powder permeability and understand the binder penetration depth. This gained understanding was then used to study how the nanoparticle solid loading in a binder affect the binder-powder interactions and the printed primitive size, which provided an understanding for determining material compatibility and printing parameters in binder jetting. / PHD

Vat photopolymerization (VP) is an additive manufacturing (AM) technology that permits the fabrication of parts with complex geometries and feature sizes as small as a few microns. These attributes make VP an attractive option for the fabrication of scaffolds for tissue engineering. However, there are few printable materials with low cytotoxicity that encourage cellular adhesion. In addition, these resins are not readily available and must be synthesized. A novel resin based on 2-acrylamido-2-methyl-1-propanesulfonic acid (NaAMPS) and poly(ethylene glycol) diacrylate (PEGDA) was formulated and printed using VP. The mechanical properties, water content, and high fidelity of the scaffold indicated promise for use in tissue engineering applications. Murine fibroblasts were observed to successfully adhere and proliferate on the scaffolds. The growth, migration, and differentiation of a cell is known to dependent heavily on its microenvironment. In engineered constructs, much of this microenvironment is provided by the tissue scaffold. The physical environment results from the scaffold's geometrical features, including pore shape and size, porosity, and overall dimensions. Each of these parameters are known to affect cell viability and proliferation, but due to the difficulty of isolating each parameter when using scaffold fabrication techniques such as porogen leaching and gas foaming, conflicting results have been reported. Scaffolds with pore sizes ranging from 200 to 600 μm were fabricated and seeded with murine fibroblasts. Other geometric parameters (e.g., pore shape) remained consistent between scaffold designs. Inhomogeneous cell distributions and fewer total cells were observed in scaffolds with smaller pore sizes (200-400 μm). Scaffolds with larger pores had higher cell densities that were homogeneously distributed. These data suggest that tissue scaffolds intended to promote fibroblast proliferation should be designed to have pore at least 500 μm in diameter. Techniques developed for selective placement of dissimilar materials within a single VP scaffold enabled spatial control over cellular adhesion and proliferation. The multi-material scaffolds were fabricated using an unmodified and commercially available VP system. The material preferences of murine fibroblasts which resulted in their inhomogeneous distribution within multi-material scaffolds were confirmed with multiple resins and geometries. These results suggest that multi-material tissue scaffolds fabricated with VP could enable multiscale organization of cells and material into engineered constructs that would mimic the function of native tissue. / Doctor of Philosophy / Vat photopolymerization (VP) is a 3D printing (or additive manufacturing) technology that is capable of fabricating parts with complex geometries with very high resolution. These features make VP an attractive option for the fabrication of scaffolds that have applications in tissue engineering. However, there are few printable materials that are biocompatible and allow cells attachment. In addition, those that have been reported cannot be obtained commercially and their synthesis requires substantial resources and expertise. A novel resin composition formulated from commercially available components was developed, characterized, and printed. Scaffolds were printed with high fidelity. The scaffolds had mechanical properties and water contents that suggested they might be suitable for use in tissue engineering. Fibroblast cells were seeded on the scaffolds and successfully adhered and proliferated on the scaffolds. The growth, migration, and differentiation of cells is influenced by the environmental stimuli they experience. In engineered constructs, the scaffold provides many of stimuli. The geometrical features of scaffolds, including how porous they are, the size and shape of their pores, and their overall size are known to affect cell growth. However, scaffolds that have a variety of pore sizes but identical pore shapes, porosities, and other geometric parameters cannot be fabricated with techniques such as porogen leaching and gas foaming. This has resulted in conflicting reports of optimal pore sizes. In this work, several scaffolds with identical pore shapes and porosities but pore sizes ranging from 200 μm to 600 μm were designed and printed using VP. After seeding with cells, scaffolds with large pores (500-600 μm) had a large number of evenly distributed cells while smaller pores resulted in fewer cells that were unevenly distributed. These results suggest that larger pore sizes are most beneficial for culturing fibroblasts. Multi-material tissue scaffolds were fabricated with VP by selectively photocuring two materials into a single part. The scaffolds, which were printed on an unmodified and commercially available VP system, were seeded with cells. The cells were observed to have attached and grown in much larger numbers in certain regions of the scaffolds which corresponded to regions built from a particular resin. By selectively patterning more than one material in the scaffold, cells could be directed towards certain regions and away from others. The ability to control the location of cells suggests that these printing techniques could be used to organize cells and materials in complex ways reminiscent of native tissue. The organization of these cells might then allow the engineered construct to mimic the function of a native tissue.

New types of laboratory reactors that are highly customizable, low-cost and easy to produce are needed to investigate low-temperature geochemical processes. We recently showed that desktop 3D printing stereolithography (SLA) can be used to efficiently fabricate a mixed flow reactor (MFR) with high dimensional accuracy comparable to traditional machining methods (Michel et al., 2018). We also showed that the SLA method allowed for the addition of complex features that are often beyond the capabilities of traditional methods. However, the stability of 3D printed parts at low-temperature geochemical conditions has not been fully evaluated. The objectives of this work were twofold: 1) to provide a framework for assessing the stability and compatibility of SLA printed materials at geochemically relevant conditions, and 2) to show how 3D printed specialty devices can enable new laboratory geochemical experiments. Part 1 of this Master's thesis presents findings for enhancing mechanical and solvent resistance properties of a commercial 3D printing material (Formlabs Clear) by UV post-curing procedures and also provide data showing its stability in aqueous solutions at pH 0, 5.7, and 12 for periods of up to 18 days. Thermal degradation patterns, mechanical analysis, and leachable fraction data are provided. Part 2 shows experiments coupling 3D printed reactors and flow devices for in situ small-angle x-ray scattering (SAXS). Schwertmannite (pH 2.7) and goethite (6.2) are precipitated from solution using various setups and observed differences in growth rates are discussed. The data show the potential of 3D printing for enabling novel laboratory geochemical experiments. / MS

The post-prognosis lifespan for those suffering with Glioblastoma (GBM) is approximately 13 months with current standard of care. Intratumoral heterogeneity is a common characteristic that hinders GBM treatment in the form of therapy resistant cell subsets and influence on cellular phenotypes. One cell subset in particular, glioma stem cells (GSCs), is frequently left behind in the brain parenchyma once the bulk of the tumor has been resected. Previous research has found that patient-derived GSCs displayed varying invasion responses with and without the presence of interstitial flow. Interestingly, GSCs from a single patient are heterogeneous, displaying differences among sub-colonies derived from the same parental line. To study the motility of cells under flow, PDMS microfluidics are commonly used. Unfortunately, this setup often involves active flow generation using pumps, limiting the number of cell lines that can be imaged at a time. To increase the throughput of GSC sub-colonies imaged simultaneously, we developed a bio-compatible, printable device fabricated to allow for passive, gravity-driven flow through a hydrogel that recapitulates the brain microenvironment, eliminating the need for pumps. Stereo lithography 3D printing was chosen as the manufacturing method for the device, and this facilitated design feature modification when prototyping, increased the potential complexity of future iterations, and avoided some of the hurdles associated with fabricating PDMS microfluidics. This printable imaging device allows for higher throughput live-imaging of cell lines to aid in the understanding of the relationships between intratumoral heterogeneity, invasion dynamics, and interstitial flow. / Master of Science / For those suffering with Glioblastoma, a high-grade brain cancer, the life span post treatment is approximately 13 months. The cells in this and many forms of cancer have physical and biological differences that make successfully eliminating the disease difficult. One of the cell types contributing to this are Glioma Stem Cells (GSCs) that are often left in brain tissue once most of the tumor has been surgically removed. Previous research has found that GSCs from different sources had different responses with and without the simulated or actual presence of flow in brain tissue. This was further complicated when different responses were observed in cells obtained when breaking apart one of the cell lines and propagating these into their own sub-colonies. The current standard for studying the movement of cells under flow is by using compact chips made of a clear silicone rubber. The setup with microfluidics typically requires connection to external tubing and pumps to create flow and this limits the amount of cell types that can be imaged at a time. In order to monitor more cells at a time we created a 3D printable device that uses gravity for flow to go through a gel that mimics brain tissue and these cells of interest. Resin 3D printing was used to make these small devices so that they could be easily re-designed for other experimental purposes in the future. Hopefully this device could be used to more rapidly gain an understanding of cell movement in GBM and other disease models.

OBJECTIVES: This study aims to determine the accuracy of 3D printed models after different storage conditions using two different material/printer systems. METHODS: A STL file of a full-arch maxillary cast was used to print 30 models from two different technologies, Carbon 3D and Formlabs 3 printers. The models were printed at 50 micrometers layer thickness. These printed models were randomized into 3 groups per printer (n=5) for storage: Room-temperature (22 ± 2 °C), low-temperature (~4 ± 1 °C), and High-temperature (50 ± 2 °C). Each of the models was scanned at a designated storage time to generate STL files, which were imported into a 3D inspection software for superimposition and evaluation of deviations using 3D comparison, points of reference, and inter-tooth distances. The trueness in this project was the absolute tooth distance difference between the reference and the testing scan. Precision in this project was the standard deviation of the tooth distances among the measurement of duplicate models within each subgroup. A regression model was used to compare the differences among the groups. RESULTS: The trueness and precision of the printed models were found significantly affected by the two printer types and different storage temperatures. Dimension changes were found to be more on the gingiva and the tooth surface of the molar area. Models under high temperatures showed expansion, while models under low temperatures presented shrinkage. Models under room temperature did not show significant distortions in general. Carbon 3D printed models showed higher in-tolerance percentages compared to Formlabs 3. CONCLUSIONS: Different printer types and storage conditions significantly affect the dimension accuracy of 3D printed dental models. Carbon 3D printed models showed less deviation compared with Formlabs 3 in terms of trueness and precision. Storage of 3D printed models at higher temperatures should be avoided to prevent dimension distortion. Lower temperature storage for the Carbon model is recommended.

Yes / This paper presents an improved mathematical model for calculation of distortion vectors of two aligned surface meshes. The model shows better accuracy when benchmarked to an existing model with exceptional mathematical conditions, such as sharp corners and small radii. The model was implemented into a developed distortion compensation digital tool and applied to an industrial component. The component was made of Inconel 718 and produced by laser powder bed fusion 3D printing technology. The digital tool was utilised to compensate the original design geometry by pre-distortion of its original geometry using the developed mathematical model. The distortion of an industrial component was reduced from approximately ±400 µm to ±100 µm for a challenging thin structure subjected to buckling during the build process.

This study investigated a new approach to achieving high energy density supercapacitors (SCs) by using high surface area self-activated carbon from waste coffee grounds (WCGs) and modifying 3D printed electrodes' porous structure by varying infill density. The derived activated carbons' surface area, pore size, and pore volume were controlled by thermally treating the WCGs at different temperatures (1000˚C, 1100˚C, and 1200˚C) and post-treating with HCL to remove water-soluble ashes and contaminants that block activated carbon pores. Surface area characterization revealed that the carbon activated at 1000˚C had the highest surface of 1173.48 m2 g-1, and with the addition of HCL, the surface area increased to 1209.35 m2 g-1. This activated carbon was used for fabricating the electrodes based on the surface area and having both micropores and macropores, which are beneficial for charge storage. Direct ink writing (DIW) method was utilized for 3D printing SC electrodes and changing the electrode structure by increasing the infill densities at 30%, 50%, and 100%. Upon increasing the infill densities, the electrodes' mass increased linearly, porosity decreased, and the total surface area increased for the 30% and 50% infill electrodes but decreased for the 100% infill electrode. Cyclic voltammetry (CV) test on the assembled SC showed the highest specific capacitance and energy density of 5.81 F g-1 and 806.93 mWh kg-1 at 10 mV s-1, respectively, for the electrode printed at 50% infill density.

There is a constant search for new sustainable materials. A material that has become increasingly more interesting is cellulose, since it is both renewable and biodegradable. By combining cellulose nanofibrils (CNF) and the polymer complex poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), a conductive hydrogel can be made. The hydrogel can subsequently be used to 3D-print various structures, which further can be used in multiple applications such as microrobots, sensors and smart devices. The aim of this bachelor thesis was to develop a 3D-printable hydrogel composed of PEDOT:PSS and CNF was made. The goal was to print and crosslink a conductive structure, and subsequently induce electrical current through the structure to facilitate movement (i.e. artificial muscles). Several hydrogel inks composed of CNF and PEDOT:PSS were prepared across a range of concentrations. Homogenisation of the hydrogels was achieved through various mixing techniques. Both freeze-drying and evaporation were tested to concentrate the hydrogels. Furthermore, crosslinking tests were performed using iron(III)chloride hexahydrate and citric acid, followed by a conductivity measurement. Lastly, rheology tests were performed on four of the inks. The optimal concentration of solid material was determined to be 4.8 wt% and the most favourable way of concentrating the hydrogels was by freeze drying. Furthermore, iron(III)chloride hexahydrate was found to be more favourable when crosslinking the hydrogels. The conductivity measurements showed that crosslinking with iron(III)chloride hexahydrate resulted in a notable increase in conductivity in the material. Lastly, the rheology measurements showed that the 4.8 wt% hydrogel ink had high elasticity, viscosity and exhibited shear thinning behaviour. / Det söks konstant efter nya hållbara material. Ett material som har blivit alltmer intressant är cellulosa, eftersom det både är förnybart och bionedbrytbart. Genom att kombinera cellulosa nanofibriller (CNF) och polymer komplexet poly(3,4-etylendioxitiofen) polystyrensulfonat (PEDOT:PSS), kan en konduktiv hydrogel framställas. Denna hydrogel kan sedan användas för att 3D-printa en mängd olika strukturer, vilka senare kan används i olika tillämpningar så som mikrorobotar, sensorer och smarta enheter. Målet med detta kandidatarbete var att utveckla en hydrogel av PEDOT:PSS och CNF för användning i 3D-skrivare. Målet var att printa och korslänka en struktur med konduktiva egenskaper, vilken senare skulle induceras med elektricitet för att främja rörelse, med andra ord artificiella muskler. Ett flertal hydrogeler av CNF och PEDOT:PSS förbereddes i en rad olika koncentrationer. Homogenisering av hydrogelerna uppnåddes genom att testa olika metoder för omrörning. Både frystorkning och avdunstning testades för att koncentrera hydrogelerna. Dessutom undersöktes tvärbindning genom järn(III)kloridhexahydrat och citronsyra, följt av en konduktivitetsmätning. Slutligen utfördes reologimätningar på fyra av de framställda hydrogelerna. Den optimala koncentrationen av fast material i en hydrogel bestämdes till 4,8 vikt% och det mest gynnsamma sättet att koncentrera hydrogeler var genom frystorkning. Vidare, var järn(III)kloridhexahydrat ett mer fördelaktigt alternativ vad gällde tvärbindning av hydrogelerna. Konduktivitetsmätningarna visade att tvärbindning med hjälp av järn(III)kloridhexahydrat ökade konduktiviteten märkbart hos materialet. Slutligen visade reologimätningarna att hydrogelen med 4,8 vikt% hade hög elasticitet, viskositet och den uppvisade även skjuvningstunnande beteende.