INTRODUCTION: Fractures and broken bones are complications within the pediatric population that frequently occur. Many children require a prolonged immobilization of an arm or leg as a result of these injuries. Physicians often place these children in casts for several weeks to months. While casting is needed for most fractures to properly heal and recover, the two most popular casts plaster and fiberglass, can cause certain complications. Parents struggle dealing with how to bathe their children without getting the cast wet. Also, it is difficult to tell how well the child's skin beneath the cast is doing during the duration of the cast immobilization. Sometimes blood blisters or rashes can develop on the surface of the child’s skin. With the rampant development of 3D printers, the printing of 3D casts has become readily available and cheap. The biggest advantages to using 3D printed casts include them being lightweight and their ability to get wet. This ongoing feasibility study looks at the clinical effectiveness of 3D printed casts in treating children with minimally displaced radius fractures. OBJECTIVES: The main objective of this feasibility study is trying to incorporate the use of 3D printing technology to pediatric patients. Other objectives include creating, designing, and placement of 3D printed casts on patients. Determine the clinical effectiveness of 3D printed casts and ensuring the patient’s fracture healed correctly. Evaluate the skin of patients who have completed a cast immobilization in a 3D printed cast. METHODS: Patients are recruited from the Children’s National Hospital Emergency Room in Washington, D.C. If a patient meets the inclusion criteria, the Chief of Pediatric Orthopedic Surgery at Children’s National Hospital will introduce the feasibility study to both the patients and their families. Once enrolled in the study, the patient will have a 3D scan taken of their injured wrist and arm with an Artec EVA, a handheld 3D scanner. The 3D scan is taken worked through multiple software programs that create a patient-specific 3D cast. The casts are printed either by an in-house 3D printer at Children’s National or outsourced to Xometry, a company that specializes in 3D printing. The patient returns one week later from the time the scan was taken and will be removed from the temporary splint they had been placed in. The Principal Investigator or the Chief of Pediatric Orthopedic Surgery will wrap the patient’s arm with AquaLiner, a waterproof cast liner. The 3D printed cast is then placed on the patient’s arm and firmly secured with eight zip-ties. Three X-rays will be taken throughout the course of the cast immobilization that may last four to six weeks. A skin assessment tool that has a scale from zero to twelve will be used by the physicians involved to evaluate the skin of the patient post-treatment. Lastly, a QuickDash survey will be filled out by the patient before being discharged and a QuickDash score that determines percent disability will be calculated on a scale of 0-100 percent. RESULTS: One patient enrolled and completed the feasibility study. The patient’s X-rays indicated their fracture healed properly while immobilized in the 3D printed cast. A score of ten out of twelve was given based on the skin assessment tool. The QuickDash score resulted in a 6.8 percent disability. The patient stated that they would have chosen the 3D printed cast over a traditional plaster cast due to the comfortability of the cast. CONCLUSIONS: Overall, the results from the one patient that completed the study proved that 3D printed casts can be used to treat minimally displaced radius fractures. The 3D printed cast was able to keep the patient’s arm in place and protect it while the fracture healed. Much of the work put into this feasibility study was the workflow needed to create and place a 3D printed cast on a patient. The appearance and design of the cast allowed the patient to feel comfortable during the entire treatment. More patients will need to be recruited and enrolled into the study to tell whether or not this project can be moved into other medical applications.

Lower back pain and intervertebral disc degeneration represent a global socio-economical problem affecting 266 million people annually, always increasing due to aging of the population. No restorative treatments are available. In case of chronic degeneration, surgical operation with spinal fusion or total disc replacement represents the best alternative. This leads to pain relief but reduces the patient’s mobility. Moreover, follow-ups and re-intervention due to weak osteointegration are common consequences of currently used metal prostheses. For this reason, there is an urgent need to develop customized regenerative approaches aimed at the restoration of IVD function, as well as the optimization of osteointegration in actual vertebral prostheses by creating hybrid metal implants with infill materials to better induce bone ingrowth. In this work, tissue engineering-based approaches have been exploited by tuning the remarkable properties of silk fibroin for two purposes, disc restoration via in situ 3D printing technique, and improvement of osteointegration of vertebral prostheses. In situ 3D printing is the most promising strategy for the development of a personalized medicine approach aimed at the restoration of IVD. However, silk fibroin application as pristine ink in 3D printing technique is hindered by its low viscosity. For this reason, the aim of the first part of the work has been the design and development of silk fibroin-based inks in situ applications, overcoming its intrinsic limitations. Specifically, a covalent crosslinking process consisting of a pre-photo-crosslinking prior to printing and in situ enzymatic crosslinking was designed. Two different silk fibroin molecular weights were characterized. We proved that despite the use of low concentration silk solutions, the synergistic effect of the covalent bonds with the shear forces applied in the nozzle enhanced silk secondary structure shift toward β-sheets conformation. The resultant hydrogels exhibited good mechanical properties, stability over time, and resistance to enzymatic degradation over 14 days, with no significant changes over time in their secondary structure and swelling behavior. The designed process was tunable and versatile, leading to good shape fidelity and printing resolutions, making real the application of silk fibroin-based inks for in situ applications. The results obtained represent an important step for further studies on the mimicry of the whole IVD structure. 2 In the second part of the work, silk fibroin has been evaluated as candidate infill material for metal prostheses to improve bone ingrowth and osteointegration. In two independent works, silk fibroin-based foams and methacrylate silk fibroin sponges were biologically characterized and the differentiation of bone marrow-derived human mesenchymal stem cells (hBM-MSCs) toward osteogenic phenotype was studied. Silk fibroin foams have been demonstrated to induce and support cells adhesion, migration, and differentiation, and to induce early mineralization phase since day 7 during the differentiative culture. Methacrylate silk fibroin foams have been fabricated with different photo-initiator concentrations and in presence/absence of a porogen. The impact of the composition on the pore size, mechanical properties, and stem cells differentiation was deeply investigated. We demonstrated that despite all the conditions well-supported cells differentiation, the lowest photo-initiator concentration in combination with the porogen used enhanced osteogenic differentiation as confirmed by gene expression tests.

ITC/USA 2014 Conference Proceedings / The Fiftieth Annual International Telemetering Conference and Technical Exhibition / October 20-23, 2014 / Town and Country Resort & Convention Center, San Diego, CA / Traditional approaches to constructing 3D structural electronics with conductive and dielectric materials include ink-jet printed, silver-bearing ink and fine copper wire meshes. One approach combines stereo-lithographic 3D-printed photo-polymers with direct-printed silver-bearing conductive inks. Results have shown 3D conductive structures with conductivities in the range 2x10⁶ to 1x10⁷ S/m using annealing temperatures ranging from 110°C to 150°C for 10 to 15 minutes. However, the stereo-lithographic approach suffers from the high cost of the printer and structural deformation during annealing. This paper presents a new method for 3d printing high conductivity metal alloys using consumer-grade 3D printer. The design and construction of the necessary modification will be presented in addition to the new 3D design process. The method yields metal structures with expected conductivities exceeding 2.6x10⁶ S/m. The process is performed without an annealing step, so the polymeric structural material is not exposed to high temperatures for any prolonged time. A UHF ISM band antenna is constructed for an RFID application using this method, the antenna performance is measured, and the results are compared simulations in Ansys HFSS. This new method can reduce total cost, and several low melting-point alloys could raise the conductivity.

abstract: Investigation into research literature was conducted in order to understand the impacts of traditional concrete construction and explore recent advancements in 3D printing technologies and methodologies. The research project focuses on the relationship between computer modeling, testing, and verification to reduce concrete usage in flexural elements. The project features small-scale and large-scale printing applications modelled by finite element analysis software and printed for laboratory testing. The laboratory testing included mortar cylinder testing, digital image correlation (DIC), and four pointbending tests. Results demonstrated comparable performance between casted, printed solid, and printed optimized flexural elements. Results additionally mimicked finite element models regarding failure regions. / Dissertation/Thesis / Masters Thesis Engineering 2020

Droplet-based microfluidic devices have become a preferred versatile platform for various fields in physics, chemistry and biology to manipulate small amounts of liquid samples. In addition to microdroplets, microbubbles are also needed for various pro- cesses in the food, healthcare and cosmetic industries. Polydimethylsiloxane (PDMS) soft lithography, the mainstay for fabricating microfluidic devices, usually requires the usage of expensive apparatus and a complex manufacturing procedure. In ad- dition, current methods have the limited capabilities for fabrication of microfluidic devices within three dimensional (3D) structures. Novel methods for fabrication of droplet-based microfluidic devices for the generation microdroplets and microbubbles are therefore of great interest in current research. In this thesis, we have developed several simple, rapid and low-cost methods for fabrication of microfluidic devices, especially for generation of microdroplets and mi- crobubbles. We first report an inexpensive full-glass microfluidic devices with as- sembly of glass capillaries, for generating monodisperse multiple emulsions. Different types of devices have been designed and tested and the experimental results demon- strated the robust capability of preparing monodisperse single, double, triple and multi-component emulsions. Second, we propose a similar full-glass device for generation of microbubbles, but with assembly of a much smaller nozzle of a glass capillary. Highly monodisperse microbubbles with diameter range from 3.5 to 60 microns have been successfully produced, at rates up to 40 kHz. A simple scaling law based on the capillary number and liquid-to-gas flow rate ratio, successfully predicts the bubble size. Recently, the emergent 3D printing technology provides an attractive fabrication technique, due to its simplicity and low cost. A handful of studies have already demonstrated droplet production through 3D-printed microfluidic devices. However, two-dimensional (2D) flow structures are still used and the advantage of 3D-printing technique has not been fully exploited. Therefore, we apply 3D printing technology to fabricate 3D-miniaturized fluidic device for droplet generation (single emulsion) and droplet-in-droplet (double emulsion) without the need for surface wettability treat- ment of the channel walls, by utilizing 3D geometry design and fabrication. A scaling law is formulated to predict the drop size generated in the device. Furthermore, magnetically responsive microspheres are also produced with our emulsion templates, demonstrating the potential applications of this 3D emulsion generator in chemical and material engineering. Finally, we design and 3D-print a hybrid ?plug-and-play? microfluidic droplet generator, which involves a 3D-printed channel chamber and commercial tubings and fittings. By combination of 3D-printed part and market-available parts, this device can be easily assembled and disassembled, which provides a great flexibility for different demands. A scaling law has been proposed for prediction of drop size generated in the device. Furthermore, a 3D-printed concentration gradient generator and a droplet merging device based on the droplet generator have been developed to demonstrate the great scalability of 3D-printing technology.

The most important rights, which state such a balance between these two parties, are the rights of intellectual property. Thus, an important question is to what extent 3D-printing conflicts with intellectual property rights. In general, intellectual property balances the rights between the owners of genuine products and their use through third parties. On the one hand the intellectual property rights give exclusive rights to the genuine owners, on the other hand they give as well some important exceptions for the use of third parts material. Hence, the purpose of this work is to examine, which intellectual property rights are affected by the production of a 3D-printed object. In each of the following chapters I will look at the different categories of intellectual property rights. I will examine in how far the creators of a CAD, the uploaders who upload a CAD on a website for a free or commercial download, the website owners who facilitate that uploads and the printers, whether private or with a commercial purpose, may be in conflict with any intellectual property rights. The most important intellectual property rights, which could be affected, are copyright, patents, registered designs, trade marks and passing off. For the present investigation it will be necessary to have a closer look at the different steps of the developing process of a 3D-printed product. More precisely, we have to differentiate between the creation of the CAD, the uploading of a CAD and finally the home-printing or the printing on demand through a specialised company. The aim of this work is to show how these single steps conflict with intellectual property rights and how the different actors in this process are liable for any infringing activity and in how far their activity is covered by any exception. Furthermore, we will also examine whether current legislation and jurisdiction appropriately address issues brought about by this new technology. Because of the reason, that the issue of 3D-printing in relation to intellectual property is quite a new one, this work will occasionally have a look abroad to other jurisdiction how they already dealt with similar problems. With this in mind, especially the US, European and German jurisdiction and laws will be regarded.

Published Article / Over the past few years, methods of layered manufacturing (LM) have advanced substantially to the point where they now provide vital strategic benefits to various organisations. One area of application where LM technologies have begun to reach a critical mass is in the development and production of high-performance tooling in different forming processes. With these tooling capabilities now available, the next challenge becomes the development of optimal process chains to minimise lead times and production costs, while still ensuring high quality of castings. The relevant issues that influence where a break-even point will be between different process chains and thereby also the point of selection between such optimal process chains according to different situations include among others: <ul> <li> the size of production runs, </li> <li> part size and complexity, and</li> <li> the cast materials involved.</li> </ul> <br>This paper reflects some of the experiences gained from an investigation towards developing a set of generic rules (guidelines) for the design of optimal process chains for sand casting prototypes of automotive components using LM methods, and more specifically the 3D Printing process.

The methodologies utilised by pharmaceutical companies for the toxicity screening of developmental drugs are currently based on outdated two-dimensional (2D) plate-based assay systems. Although such methods provide high-throughput analysis, limitations surrounding the biomimicry of the culture environment reduces the accuracy of testing, making the process cost and time inefficient. To significantly enhance the current methods, a screening platform that is both flexible in its design and is amenable toward physiologically representative engineered tissue is required. Incorporating a flow environment within the system elicits a variety of advantages over standard static cultures, pertinently the ability to couple the flow path with automated analytical systems via the use of intuitive software. Musculoskeletal pathological conditions account for £4.76 billion of NHS spending as of 2011 (Department of Health), affecting one in four of the UK adult population. Skeletal muscle, a highly metabolic and regenerative tissue, is involved in a wide variety of functional, genetic, metabolic and degenerative pathological conditions such as muscular dystrophy, diabetes, osteoarthritis, motor neuron disease and pertinently muscular weakness associated with aging populations. Skeletal muscle tissue engineering is centred on the in vitro creation of in vivo-like tissue within laboratory environments and seeks to aid the development of future therapies, by reliably elucidating the molecular mechanisms that regulate such conditions. However, the translation of such models toward systems amenable to pharmaceutical companies has to date been limited. Microphysiological perfusion bioreactors for in vitro cell culture are a rapidly developing research niche, although state of the art systems are currently limited due to the biologically non-representative 2D culture environment, lack of adaptability toward different experimental requirements and confinement to offline analytical methods. Advancements in additive manufacture (AM), commonly known as three-dimensional (3D) printing has provided a method of production that enables researchers to hold complete design freedom and facilitate customisation of required parts. The low cost, rapid prototyping nature of AM further lends itself toward the development of such technology, with design iterations quickly and easily printed, tested and re-designed where appropriate. Issues do however, currently persist regarding the biological compatibility of printed polymers and functional material properties of parts created. As such, this thesis investigated the use of AM as a rapid and functional prototyping technique to design and develop microphysiological perfusion bioreactors. Here, biocompatibility of candidate polymers derived from commercially available 3D printing processes; fused deposition modelling (FDM), stereolithography (SL), selective laser sintering (LS) and PolyJet modelling (PJM) were elucidated. Following the biological evaluation of these polymers, their suitability, and the applicability of each process in function and manufacture of perfusion bioreactors were assessed alongside the research and development process of system designs. Specifically, attention was afforded to the homeostatic environment within bio-perfusion systems. Once finalised, the biological optimisation of designs; biocompatibility and rates of proliferation in response to the perfusion environment, was undertaken. Protocols were then established for the automated perfusion of skeletal muscle cells in both monolayer and tissue engineered 3D hydrogels. This research outlined significant contributions to the scientific literature in 3D printed polymer biocompatibility, in addition to creating bio-perfusion systems that are adaptable, analytical and facilitate the in situ phenotypic development of physiologically representative skeletal muscle tissue. Polymer biocompatibility elucidated in this work will help to facilitate the wide-ranging use of AM in biological settings. However, advancements in the chemical properties of liquid resins for advanced photo-curable processes remain necessitated for AM to be considered as a primary manufacturing technique in the biological sciences. Furthermore, although systems developed in this work have provided a base technology from which to develop and build upon, significant challenges remain in the integration of tissue engineered perfusion devices within pharmaceutical settings. Although it is plausible that the technology created in its current guise would facilitate the automated generation of skeletal muscle tissue, systems require further development to aid their usability and scale. Furthermore, work is also required to optimise the biological environment prior to mass manufacture. As such, to truly influence the pharmaceutical industry, which has invested so heavily in more traditional screening technology, a system that is all-encompassing in biology, technology and automated analytics is required.

Tissue engineering (TE) integrates methods of cells, engineering and materials to improve or replace biological functions of native tissues or organs. 3D printing technologies have been used in TE to produce different kinds of tissues. Based on review of the exiting 3D printing technologies used in TE, special requirements of fabricating soft scaffolds are identified. Soft scaffolds provide a microenvironment with biocompatibility for living cells proliferation. This research focuses on 3D printer design and printing parameters investigation for fabrication of soft scaffolds. A 3D printer is proposed for producing artificial soft scaffolds, with components of a pneumatic dispenser, a temperature controller and a multi-nozzle changing system. Relations of 3D printing parameters are investigated to improve the printing quality of soft scaffolds. It provides guidance for printing customized bio-materials with improved efficiency and quality. In the research, printing parameters are identified and classified based on existing research solutions. A deposition model is established to analyze the parameters relations. Quantitative criteria of parameters are proposed to evaluate the printing quality. A series of experiments including factors experiments and comparison tests are conducted to find effects of parameters and their interactions. A case study is conducted to verify the analytic solution of proposed models. This research confirms that the hydrogel concentration and nozzle diameters have significant effects on the filament diameter. Factor interactions are mainly embodied in between the concentration of hydrogel solutions and dispensing pressures. Besides filament diameters, the nozzle height and space also affect the printing accuracy significantly. An appropriate nozzle height is considered to be 1.4 times than the nozzle diameter, and a reasonable nozzle space is suggested from 2.0 to 2.5 times of the nozzle diameter.

abstract: This research work demonstrates the process feasibility of Ultrasonic Filament Modeling process as a metal additive manufacturing process. Additive manufacturing (or 3d printing) is the method to manufacture 3d objects layer by layer. Current direct or indirect metal additive manufacturing processes either require a high power heat source like a laser or an electron beam, or require some kind of a post processing operation to produce net-shape fully-dense 3D components. The novel process of Ultrasonic Filament Modeling uses ultrasonic energy to achieve voxel deformation and inter-layer and intra-layer mass transport between voxels causing metallurgical bonding between the voxels. This enables the process to build net-shape 3D components at room temperature and ambient conditions. Two parallel mechanisms, ultrasonic softening and enhanced mass transport due to ultrasonic irradiation enable the voxel shaping and bonding respectively. This work investigates ultrasonic softening and the mass transport across voxels. Microstructural changes in aluminium during the voxel shaping have also been investigated. The temperature evolution during the process has been analyzed and presented in this work. / Dissertation/Thesis / Masters Thesis Engineering 2016