Our aim is to answer whether or not 3D printing is capable of achieving mass customization and mass production, since answering this might help predict a shift within manufacturing industries and the use that this technology has had the past years. Further, our aim is to give an overall view of the industry of companies offering 3D printed goods for end use through an e-commerce marketplace and its value creating activities. The overall aim is to contribute to fill the academic gap regarding research on 3D printing within the field of mass customization and provide groundwork for future research. To provide the current picture of the industry and thus analyze its capabilities regarding mass production and mass customization, we present the value chain with the involved value creating activities. We have conducted three qualitative interviews to three out of four companies within the industry complemented as well with an exhaustive research to the websites of the companies.

Introduction: Peritoneal carcinomatosis is an end stage sequela occurring in 10% of patients with colorectal cancer. Palliative approaches have evolved over the past several decades and the role for surgical cytoreduction with hyperthermic intraperitoineal chemotherapy (HIPEC) has proven efficacy in several studies. Optimization of HIPEC therapy includes the addition of adjuncts to the carrier solution of intraperitoneal chemotherapy to improve tumor cell killing. In this study the addition of vitamin C, selenium, and quercetin ("micronutrient combination") to mitomycin C is evaluated in-vitro, and a novel murine model of HIPEC is developed using a hyperthermic chemotherapy infuser device designed de novo and printed on a 3D resin printer. Methods: HCT-116 cells were grown in culture and divided into treatment groups including: control, micronutrient combination, mitomycin C, and mitomycin C + micronutrient combination. Groups were cultured up to 72 hours after treatment and then subjected to MTT assay, crystal violet assay, trypan blue synergy assay, clonogenicity assay, cell cycle assessment by flow cytometry with propidium iodide, and western blotting for cleaved caspase-3. The infuser device was designed in a CAD environment, printed on a 3D resin printer, and underwent fluid temperature stability analysis and flow experiments by infusing methylene blue into live mice followed by necropsy and analysis of dyeing patterns. Results: MCC treated cells proliferated at 32.7%, and tumor cells treated with MCC + MNC carrier solution proliferated at 27.3%. Normothermic MCC and the MNC alone caused a 26.8% and 33.3% reduction in cell survival, and MCC delivered to cells in the micronutrient combination solution decreased cell survival by 53.2%. 95.3% and 99% of cells treated with MCC or MNC alone demonstrated viability, and 85% of cells treated with MCC + MNC demonstrated short term viability, suggesting synergy. HCT-116 clonogenicity is disrupted by MCC and MNC individually, and nonexistent in the MCC + MNC treatment group. Cleaved caspase-3 mediated apoptosis is upregulated by MCC, and by MNC to a lesser extent. Flow cytometry apoptosis demonstrates increased S-phase cell cycle arrest in the MCC + MNC sample. The mouse infuser HIPEC apparatus demonstrated an thorough distribution of blue dye in predictable regions of the abdomen with an acceptable range of hyperthermic regulation.

A limiting factor in the digitization of dental devices is the availability of materials suitable for use in both dentistry and the new digital technologies. As a rapidly growing industry, three-dimensional printing (3DP) has the potential to disrupt traditional manufacturing and prototyping methods. A review of both restorative materials and the current 3DP materials has lead to a focus on fiber- reinforced composites in the exploration for a new 3DP material. In addition, another area worth exploring and investing in would be 3D bioprinting as it opens up the possibility of regenerative dentistry.

Large Area Maskless Photopolymerization (LAMP) is a novel additive manufacturing technology currently being developed at Georgia Tech in collaboration with the University of Michigan at Ann Arbor and PCC Airfoils. It is intended for the fabrication of integrally cored ceramic molds for the investment casting of precision components such as high-pressure turbine blades. This dissertation addresses the digital data processing and computational design needs for this technology. Several data processing schemes like direct slicing, STL slicing, post-processing schemes like error checking, part placement and tiling etc. were developed in order to enable the basic functionality of the LAMP process. A detailed overview of these schemes and their implementation details are given in this dissertation. Several computational schemes to improve the quality and accuracy of parts produced through the LAMP process were also implemented. These include a novel volume deviation based adaptive slicing method to adaptively slice native CAD models, a gray scaling and dithering approach to reduce stair stepping effect on downward facing surfaces and a preliminary experimental study to characterize the side curing behavior of the LAMP photo-curable suspension for pre-build image compensation. The implementation details and a discussion of the results obtained using these schemes are given. A novel approach for addressing the “floating island” problem encountered in additive manufacturing was also developed. The need for supports specific to the kind of parts being built through LAMP is evaluated and a support generation strategy different from the previously reported approaches in the literature is presented. Finally, a few novel film cooling schemes that are extremely challenging to fabricate using existing manufacturing technologies but possible to fabricate using LAMP are chosen and analyzed for their cooling performance. It is shown that such novel schemes perform much better in cooling the blade surface than the conventionally implemented schemes and hence this final component of work gives a better appreciation of the impact LAMP technology has in disrupting the state of the art in turbine blade manufacturing and truly taking the blade designs to the next level.

Inkjet printing of ceramic components and gold conductive tracks was carried out in this study. A commercial inkjet printer, designed for printing one layer of 2D images on paper, was modified to give adequate resolution, to reverse the substrate for overprinting many layers and to accommodate the increase in thickness of 3D components during printing. Ceramic inks were prepared by wet ball milling and printed to form 3D structures. The powders used were alumina, zirconia, lead zirconate titanate (PZT) and barium titanate. The substrate used for printing the ceramic parts was an overhead transparency. Methods to stop or reduce ink flow were devised and used during printing of the ceramic parts. The alumina and zirconia powders were used for the fabrication of multi-layered laminates. The lead zirconate titanate was used to fabricate components with pillars, walls, vertical channels and x-y-z channel network. During printing of the x-y-z channel network, carbon was used as a support structure and then removed during firing. Barium titanate and carbon powders were used to form the first storey of a capacitor with a multi-storey car park structure. The printed parts were pyrolysed and fired in an oxidising environment and then characterised with scanning electron microscopy. The causes of micro structural defects found were discussed and prevention methods suggested. Organic gold powder was dissolved in methanol and then printed on three different substrates to form conductive gold tracks. The substrates used included alumina, glazed tile and microscope glass slides. The printed tracks were fired in air. The decomposition characteristics of the organic gold compound were studied with TGA and Differential Scanning Calorimetry (DSC). Scanning electron microscope was used to examine the fired gold film for defects and conductivity measurement of the tracks was carried out with a programmable multimeter.

Inkjet printing is a mature technique for colourful graphic arts. It excels at customized, large area, high resolution, and small volume production. With the developments in conductive, and dielectric inks, there is potential for large area inkjet electronics fabrication. Passive radio frequency devices can benefit greatly from a printing process, since the size of these devices is defined by the frequency of operation. The large size of radio frequency passives means that they either take up expensive space “on chip” or that they are fabricated on a separate lower cost substrate and somehow bonded to the chips. This has hindered cost-sensitive high volume applications such as radio frequency identification tags. Substantial work has been undertaken on inkjet-printed conductors for passive antennas on microwave substrates and even paper, yet there has been little work on the printing of the dielectric materials aimed at radio frequency passives. Both the conductor and dielectric need to be integrated to create a multilayer inkjet printing process that is capable of making quality passives such as capacitors and inductors. Three inkjet printed dielectrics are investigated in this thesis: a ceramic (alumina), a thermal-cured polymer (poly 4 vinyl phenol), and a UV-cured polymer (acrylic based). For the conductor, both a silver nanoparticle ink as well as a custom in-house formulated particle-free silver ink are explored. The focus is on passives, mainly capacitors and inductors. Compared to low frequency electronics, radio frequency components have additional sensitivity regarding skin depth of the conductor and surface roughness, as well as dielectric constant and loss tangent of the dielectric. These concerns are investigated with the aim of making the highest quality components possible and to understand the current limitations of inkjet-fabricated radio frequency devices. An inkjet-printed alumina dielectric that provides quality factors of 200 and high density capacitors of 400 pF/mm2 with self-resonant frequencies into the GHz regime is developed in this thesis. A multilayer fully printed process is demonstrated using PVP dielectric and dissolving type vias, giving better than 0.1 ohm resistance. In the multilayer process, capacitors and inductors have self-resonant frequencies around 1GHz. These fully printed devices have quality factors less than 10. Finally, 3D inkjet-printed UV-cured material is utilized with a novel silver organo-complex ink at 80oC providing conductivity of 1x107 S/m. A lumped element filter is demonstrated with an insertion loss of only 0.8 dB at 1GHz. The combination of inkjet printing 3D polymer and conductive metal together allows for complex shapes. A fully printed antenna with 81% radiation efficiency is shown. With these promising results and future advances in conductive inks and low-loss dielectrics, the performance of inkjet passives could one day overcome conventional fabrication methods.

OBJECTIVE: To explore a novel virtual inspection approach with a 3D metrology software to provide a non-destructive in situ analysis in digital workflow. Also, to evaluate the fit discrepancies of lithium disilicate crowns by using such a novel virtual measuring technique. MATERIALS AND METHODS: Maxillary arch typodont was used to design abutment for tooth #8 and #14 (hand prepared) and #4 and #10 (titanium custom abutment). All four abutments were placed into a duplicated maxillary arch solid stone model for scanning with laboratory scanner. Four crown patterns were designed and exported as STL files. The internal control group consists of the four original digital STL files and the external control group which was the 32-milled lithium disilicate crowns (IPS e.max® CAD, Ivoclar Vivadent, Inc.), eight patterns for each tooth. Thirty-two pressable wax patterns (8 of each) was fabricated for each of the three different technique systems. Two printed wax systems, Varseo Wax CAD/Cast (BEGO) and Press-E-Cast (EnvisionTec). Two milled wax systems Harvest Wax (Ivoclar Vivadent, Inc.) and Polycon Cast (Straumann), and a set of conventional cutbacks of 1.5mm with applied marginal wax. All patterns were pressed into lithium disilicate crowns, then fine polished and scanned. Each file was imported into a quality control metrology software (Geomagic Control X, 3D Systems) for marginal fit and internal fit evaluation with respective digital abutment. RESULTS: Mean of marginal gap for all groups were all lower than the preset gap space of 40 microns. Statistically significant differences in the fit accuracy were found among tooth number, technique system and measurement locations, but the differences are in clinically acceptable range. New scope of analyzing a restoration in a 3D fashion can help solve clinical complications. The study has shown that lower marginal gap does not necessary indicates a better fit restoration, as every level of the crown should be evaluated for. CONCLUSION: This novel inspection method can be used as a replacement of fit checker and help clinician to work in a full digital workflow. Lithium disilicate restorations fabricated through printed wax pattern, milled wax pattern and conventional hand wax are all clinically acceptable techniques. / 2019-09-26T00:00:00Z

This thesis investigates the application of online monitoring for the optimisation of flow chemistry, as well as how additive manufacturing can aid the integration of analysis and confer new functionality to flow reactors. The additive manufacturing (AM) processes used were stereolithography (SL) and the metal printing techniques selective laser melting (SLM) and ultrasonic consolidation (UC). Chapter 1 contains a short literature review, intended to give a clear background to the work contained herein. The literature reported gives a brief introduction to flow chemistry and some of the instrumentation used to perform it. Additionally, the evolution of reactor design is investigated leading to an overview of the use of AM for custom reactors. The subsequent use of online analytical technologies and how they relate to the enhancement of flow chemistry is discussed, as well as some of the protocols that have been employed to date to facilitate automated reaction optimisation. Chapter 2 investigates the design and manufacture of flow cells capable of online spectroscopy, as well as the integration of spectroscopic monitoring capability directly into reactors. In addition, the use of AM to produce accessories, not necessarily part of the wetted flow path, was investigated and showed that many useful parts such as fibre optic holders and screws could be produced. The capability of these flow cells was assessed through standard material analysis as well as through the online analysis of flow chemistry. In particular, the use of SL has enabled the production of flow cells with features smaller than 100 microns. This allowed in situ spectroscopy to be performed by embedding fibre optics directly adjacent to the flow channel, offering a new way for reaction monitoring by ultraviolet (UV) spectroscopy to be performed cheaply, and with full user control over the flow cell specification. No additional quartz features were required for these cheap and highly customisable parts. Flow cells of larger path lengths were also produced, and their performance tested, identifying designs and materials suitable for the inline analysis of flow chemistry. These designs were then successfully incorporated directly within the flow channels of larger scale reactors, tailored specifically to commercial flow equipment, for true inline analysis of flow chemistry. Chapter 3 examines the use of metal reactors formed through more expensive printing processes, SLM and UC. As the parts these techniques produce are fully dense, chemically resistant and thermally stable, they were used to perform high temperature chemistry, taking solvents substantially above their boiling points to accelerate reactions and perform them in a fraction of the time of the batch process. UC was also used to produce a reactor with a copper flow path and the possibility of reaction catalysis performed with active metal sections was investigated, revealing that chemical modification of the reactor surface greatly improved the reaction yield. UC was also utilised to produce a flow reactor incorporating a thermocouple in the main body, close to the flow channel to enable accurate reaction temperatures to be measured, a significant improvement over the temperature control offered through the flow instrument. This represents the first use of UC for the production of complicated geometry flow reactors and this work has shown that many more applications of the technique for flow chemistry should be investigated. The ability to perform light mediated coupling reactions in AM produced reactors was also demonstrated successfully for the first time, and further to this that the extended UV curing of SL reactors is crucial for improved robustness of these parts. Chapter 4 centres on the use of online analytical methods to provide rapid, selective, and quantitative online analysis of flow chemistry. This chapter also outlines some of the steps required for automation to be possible, including equipment specifications and the coding approach undertaken to integrate multiple different instruments. A combination of online nuclear magnetic resonance (NMR) spectroscopy analysis and automated experiment selection was then used to optimise a pharmaceutically relevant, photoredox catalysed, C-N coupling reaction between amines and aryl halides, performed under continuous flow conditions for the first time. This optimisation required minimal user input, operating completely unattended, and revealed that lower concentrations of catalyst could be employed than previously identified, reducing the amount of toxic and expensive metal salts required, while achieving high conversion of the starting material. In summary, this thesis has demonstrated that AM, in particular SL, can be used for the production of new high resolution microfluidic flow cells, as well as larger scale flow cell designs which can be integrated into the body of large reactors, not easily performed with other manufacturing methods. SL has also been used to produce reactors capable of performing light catalysed reactions directly, with no further modifications. The use of metal printing AM techniques has allowed in situ catalysis and high temperature, high pressure reactions to be carried out with ease. Finally, the use of online NMR with computer control and experiment automation has allowed the rapid optimisation of a pharmaceutically important C-N coupling reaction.

Vascularization is essential for living tissue and remains a major challenge in the field of tissue engineering. A lack of a perfusable channel network within a large and densely populated tissue engineered construct leads to necrotic core formation, preventing fabrication of functional tissues and organs. While many approaches have been reported for forming vascular networks, including materials processing techniques, such those involving lithography, bioprinting, and sacrificial templating; and cell-based approaches, in which cellular self-organization processes form vessels; all are deficient in their ability to form a vessel system of sufficient complexity for supporting a large cellular construct. What is missing from the literature is a method for forming a fully three-dimensional vascular network over the full range of length-scales found in native vessel systems, which can be used alongside cells and perfused with fluids to support their function. A large number of research groups are thus pursuing novel methods for fabricating vascular systems in order that new tissues and organs can be fabricated in the lab. In this project, a 3D printing-based approach was used to form vascular networks which are hierarchical, three-dimensional, and perfusable. This was performed in thick, cellularized hydrogels similar in composition to native tissue; these being collagen (ECM-like) and fibrin (woundlike), both of which are highly capable of supporting cellular activities, such as cell seeding, cell spreading, and capillary morphogenesis. In order to make use of 3D printed network templates in cellularized hydrogel environments, it was necessary to develop a new approach in which standard 3D printed materials were converted into a gelatin template, via an alginate intermediary, which can be removed quickly in physiologic conditions and which does not reduce cell viability. This multi-casting approach enables a hierarchical channel network to be formed in three-dimensions, capable of being perfused with cell medium to maintain the viability of a cell population, thereby addressing the fundamental problem. Using standard cell staining and immuno-histochemistry techniques, we showed good endothelial cell seeding and the presence of tight junctions between the channel endothelial cells. When fibroblasts were seeded into the bulk of the hydrogel, a high degree of cell viability and cell spreading was observed when a threshold flow rate is met. By counting the number of live and dead cells in a sample regions of the gel, we were able to show a dependency of cell viability upon the perfusion flow rate and further determine a regime in which the vast majority of cells are alive and spreading. This data informs future cellular experiments using this platform technology. The limits of existing 3D printing technology meant that the micro-scale vasculature needed to be formed by other means. Cellular co-culture of endothelial and stromal cell types has been shown to be capable of forming capillary-like structures in vitro. For inclusion with the 3D printed channel system, we investigated the use of an angiogenic method for capillary formation, using multi-cellular spheroids, and a vasculogenic approach, using individual cells, in order that the full vascular system could be constructed. Endothelial and mesenchymal stromal cells were encapsulated in small fibrin and collagen gels and maintained under static culture conditions in order to form capillaries by the above approaches. The aim here was to find a particular gel composition and cell concentration which would support capillary morphogenesis while being suitably robust to handle the mechanical stresses associated with perfusion. As future work, the next step will be to incorporate the vasculogenic co-culture technique, used to form capillary-sized vessels, into a perfusable gel containing the large templated channels, formed via the multi-casting approach. The challenge here is to anastomose the capillary-sized vessels to the large templated channels and thereby enable perfusion of the capillary vessels. This step would be a highly significant development in the field as it would mean large constructs could be fabricated with physiological densities of cells, which could lead to a range of potential therapeutic applications.

abstract: The objective of the research is to test the use of 3D printed thermoplastic to produce fixtures which affix instrumentation to asphalt concrete samples used for Simple Performance Testing (SPT). The testing is done as part of materials characterization to obtain properties that will help in future pavement designs. Currently, these fixtures (mounting studs) are made of expensive brass and cumbersome to clean with or without chemicals. Three types of thermoplastics were utilized to assess the effect of temperature and applied stress on the performance of the 3D printed studs. Asphalt concrete samples fitted with thermoplastic studs were tested according to AASHTO & ASTM standards. The thermoplastics tested are: Polylactic acid (PLA), the most common 3D printing material; Acrylonitrile Butadiene Styrene (ABS), a typical 3D printing material which is less rigid than PLA and has a higher melting temperature; Polycarbonate (PC), a strong, high temperature 3D printing material. A high traffic volume Marshal mix design from the City of Phoenix was obtained and adapted to a Superpave mix design methodology. The mix design is dense-graded with nominal maximum aggregate size of ¾” inch and a PG 70-10 binder. Samples were fabricated and the following tests were performed: Dynamic Modulus |E*| conducted at five temperatures and six frequencies; Flow Number conducted at a high temperature of 50°C, and axial cyclic fatigue test at a moderate temperature of 18°C. The results from SPT for each 3D printed material were compared to results using brass mounting studs. Validation or rejection of the concept was determined from statistical analysis on the mean and variance of collected SPT test data. The concept of using 3D printed thermoplastic for mounting stud fabrication is a promising option; however, the concept should be verified with more extensive research using a variety of asphalt mixes and operators to ensure no bias in the repeatability and reproducibility of test results. The Polycarbonate (PC) had a stronger layer bonding than ABS and PLA while printing. It was recommended for follow up studies. / Dissertation/Thesis / Masters Thesis Civil, Environmental and Sustainable Engineering 2018