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.

<p dir="ltr">Repeated loading and unloading cycles lead to the formation of strain in the material which causes initiation of the crack formation this phenomenon is called fatigue. Fatigue properties are critical for structures subject to cyclic load; hence fatigue analysis is used to predict the life of the material. Fatigue analysis plays an important role in optimizing the design of the 3D printed material and predicting the fatigue life of the 3D printed component.</p><p><br></p><p dir="ltr">The main objective of this thesis is to predict the fatigue behavior of different microstructures of Ti-64 titanium alloy by using the PRISMS-Fatigue open-source framework. To achieve this goal Ti-64 microstructure models were created using programming scripts, then the structures were exported to a finite element visualization software package, with all the required properties embedded in the pipeline. The PRISMS-Fatigue framework is used to conduct a fatigue analysis on 3D printed materials, using the Fatigue Indicator Parameters (FIP), which measure the driving force of fatigue crack formation in the microstructurally small crack growth.</p><p><br></p><p dir="ltr">Three different microstructures, i.e., cubic equiaxed, random equiaxed, and rolled equiaxed microstructures, are analyzed. The FIP results show that the cubic equiaxed grains have the best fatigue resistance due to their isotropic structural characteristics. Additionally, the grain size effect using 1 and 10 micrometers is investigated. The results show that the 1 micrometer grain size cubic equiaxed microstructure has a better fatigue resistance because as grains are small and they have a higher mechanical strength.</p>

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.

Histotripsy is a non-invasive, non-thermal, and non-ionizing therapy that utilizes converging high-pressure ultrasound waves at a focal point to produce cavitation and induce mechanical tissue destruction. Currently, rapid prototyped histotripsy transducers consist of multiple elements and are made using 3D printing methods. Multi-element transducers introduce size constraints and 3D printing has limitations in material choice, cost, and time for larger scale manufacturing. This thesis investigates the development of rapid prototyped single element histotripsy transducers and the use of injection molding for transducer fabrication, utilizing an in-house metal CNC mill for mold manufacturing and a desktop injection molding machine. Nylon 101 and 30% glass-filled nylon were chosen as the plastics to inject as these were found to have the most similar acoustic properties to WaterShed, an ABS-like plastic currently used. Six single-element transducers were constructed with a 2 MHz curved Pz26 piezoceramic disc: two with SLA 3D printed housing, two with SLS 3D printed housing, and two with injection molded housing. Electrical impedance, beam dimensions, focal pressure output, and cavitation were characterized for each element. The results show that rapid prototyped single element transducers can generate enough pressure to perform histotripsy. This marks the development of the first rapid prototyped single element histotripsy transducer and further confirms that injection molding can produce transducers comparable, if not identical or potentially superior, to 3D printed counterparts. Future work aims to further characterize these transducers, explore more material options, and apply injection molding to various transducer designs while optimizing both CNC and injection molding parameters. / Master of Science / Histotripsy is a form of cancer therapy that can non-invasively treat tumors using focused ultrasound waves. Focused ultrasound transducers are used to achieve this and are currently prototyped using 3D printing. However, these methods are limiting in material options and upscale manufacturing. Many of these devices currently used tend to be larger in size, comparable to the size of a mixing bowl, which limits its applications. This thesis investigates the development of single element histotripsy transducers and the use of injection molding for transducer fabrication, using an in-house metal CNC mill for mold manufacturing and desktop injection molding machine. Nylon 101 and 30% glass-filled nylon were chosen as the plastics to inject due to their ideal acoustic properties. Six single-element transducers were constructed: two with SLA 3D printing, two with SLS 3D printing, and two with injection molding. All transducers were tested and compared against each other. The results show that 3D printed single element transducers can perform histotripsy and that injection molding can produce comparable results. Future work should continue to test and characterize these transducers, explore more material options for injection molding, apply injection molding to other transducer designs, and optimize CNC and injection molding parameters.

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 / The binder jetting Additive Manufacturing (AM) process can be used to fabricate net-shape metal parts with complex geometries by selectively inkjet printing a liquid binding agent into a powder bed, followed by post-process sintering of the printed green parts. Motivated by the need to create highly efficient thermal management systems, this work has established a binder jetting manufacturing process chain for fabricating components made of pure copper, a conductive and optically reflective material that is challenging to be processed by laser-based AM systems. In order to improve the performance metrics (e.g., mechanical strength, electrical and thermal conductivity) of the printed copper parts, an overall strategy to improve powder bed packing density by filling the powder bed voids with fine particles was investigated. Through the use of a bimodal powder mixture and a nanoparticle binder, the sintered density and structural integrity of the printed parts were improved. Via the investigation of these novel material systems created for binder jetting of copper, (i) the gaps in understanding the relationship between printed part properties and powder bed particle size distribution were filled, and (ii) an experimental approach to characterize and understand the binder-powder interaction and printed primitive formation was created to guide the selection of printing parameters in binder jetting.

FDM 3D printing is an additive manufacturing technology that is widely used, mainly for rapid prototyping. It is also one of the cheapest and most accessible AM technologies for consumers. FDM printers, and especially cheaper alternatives, can have problems with creating high quality prints. Reasons include poor design, inaccurate construction, cheap components, and improper tuning. Input shaping is a control technique that may help mitigate defects caused by poor mechanical design or construction. The “ringing” defect may be eliminated by applying this solution. To perform an evaluation in sub-optimal mechanical conditions a 3D printer was constructed with a cantilever design mainly using plastic prints for mechanically important parts. Printing tests were done with and without input shaping. The results that were produced showed a direct effect of input shaping in 3d printers. / FDM 3D-printing är en additiv tillverkningsteknik som är mycket använd, främst för snabb prototypering. Det är också en av de billigaste och mest tillgängliga AM-teknikerna för konsumenter. FDM skrivare, och särskilt billigare alternativ, kan ha problem med att skapa högkvalitativa utskrifter. Orsaker inkluderar dålig design, konstruktionfel, billiga komponenter och felaktig justering. Input shaping är en kontrollteknik som kan hjälpa till att mildra defekter som orsakas av dålig mekanisk design eller konstruktion. "Ringning" defekten kan elimineras genom att tillämpa denna lösning. För att utföra en utvärdering i dåliga mekaniska förhållanden konstruerades en 3D-skrivare med en fribärande design som använder plastutskrifter för mekaniskt viktiga delar. Utskriftstester gjordes med och utan input shaping. Resultaten som framställdes visade på en uppenbar förbättring av print kvalité som en direkt effekt av input shaping.

Saab Surveillance in Järfä̈lla constructs complex products, such as radars and electronic support measures. Saab sees an advantage in manufacturing details with additive manufacturing as it enables a high level of complexity. Additive manufacturing is relatively new in the industry and consequently there are uncertainties regarding the process. The purpose of this bachelor thesis was to improve the knowledge of the repeatability of additive manufactured parts as well as compare additive manufactured test rods in two different directions, horizontally and vertically, to subtractive manufactured test rods with a vibration test. The vibration test was conducted to simulate the operative environment where the additive manufactured parts might be implemented in the future. Before the vibration test could be performed, the test rods were designed in a 3D-modeling program and analysed with a finite element method to achieve the required natural frequency range of 100 - 200 Hz and a maximal bending stress of 60 - 80 MPa in the notched area of the test rod. It was concluded that the subtractive manufactured test rods had the highest repeatability. The horizontally additive manufactured test rods had a higher repeatability than the vertically additive manufactured test rods, but the vertically additive manufactured test rods had the highest overall strength. It was also concluded that more studies are needed to ensure that additive manufactured parts can be produced with high repeatability while maintaining the structural integrity. / Saab Surveillance i Järfä̈lla konstruerar komplexa försvarsprodukter som till exempel radarsystem. Additiv tillverkning i metall möjliggör tillverkning av produkter med hög komplexitet, men då tillverkningsprocessen är relativt ny i industrin finns det en stor osäkerhet kring processen. Syftet med detta kandidatexamensarbete var att få en bättre förståelse för repeterbarheten hos additivt tillverkade delar samt att jämföra additivt tillverkade provstavar konstruerade i två olika riktningar, horisontellt och vertikalt, med svarvade provstavar med hjälp av ett vibrationstest. Vibrationstestet genomfördes för att simulera den operativa miljön där de additivt tillverkade detaljerna skulle kunna implementeras i framtiden. Innan vibrationstestet kunde utföras simulerades provstavarnas design i en mjukvara för 3D-modellering. En finit element-analys utfördes även fö̈r att få en egenfrekvens inom intervallet 100 - 200 Hz och en maximal böjspänning mellan 60 - 80 MPa i anvisningen på provstaven. Slutsatsen drogs att de traditionellt bearbetade stavarna hade den högsta repeterbarheten. De horisontellt additivt tillverkade stavarna hade högre repeterbarhet än de vertikalt additivt tillverkade stavarna, men att de vertikalt additivt tillverkade stavarna hade ett längre utmattningsliv. Det kunde även konstateras att fler studier inom ämnet behövs för att kunna säkerställa repeterbarheten hos additivt tillverkade delar utan att behöva kompromissa med hållfastheten.