Additive Manufacturing (AM, also known as 3D printing) can produce novel three-dimensional structures using low-loss dielectric materials. This enables the construction of dielectrics with complex shapes that enable innovative microwave applications such as resonators, filters, and metamaterial lenses. This thesis addresses the production and characterization of cellular structures of various designed densities created with a low loss ceramic material, alumina (aluminum oxide), via vat photopolymerization. The permittivity of these printed structures is variable over roughly an octave, with a range of relative permittivites from 1.78 to 3.60, controlled via part geometry. Two additional materials, ferrite and nickel, have been explored for inclusion within these dielectric structures to enable the production of multi-material electromagnetic structures with conductive, magnetic, and dielectric elements. / Master of Science / Additive Manufacturing (AM, also known as 3D printing) has unique manufacturing capabilities. 3D printing can create structures that cannot be produced using traditional manufacturing methods. For example, sponge like structures, with internal voids inaccessible from the outside of the structure, can be created out of a variety of materials. Such structures, known as cellular structures, can be used to create new advanced materials. Ceramic cellular structures can be produced using 3D printing. Ceramics possess many advantages over other materials for use in high frequency radio systems, such as those used for radar and communications. Notably, ceramics are known as low-loss materials, meaning that when electromagnetic waves travel through them they lose less energy than other materials. Cellular structures can be used to vary a material property known as the dielectric constant. Creating cellular structures with designed dielectric constants will enable the creation of new and useful electromagnetic structures. Measuring how this material property changes with the geometry of the cellular structures is important to enable their use. These measurements are described in this work. Additionally, other materials are printed into the ceramic structures. Ferrite, a magnetic material, is extruded as a paste from a nozzle into the ceramic structures. This material is also important for radio systems. Nickel, a good conductor, has also been embedded into the ceramic to provide the ability to create electrically conductive paths inside the part.

High performance communications, sensing and computing systems are growing exponentially as modern life continues to rely more and more on technology. One of the factors that are currently limiting computing and transmission speeds are copper wire interconnects between devices. Optical fiber interconnects would greatly increase the speed of today’s electronic devices. In this study it has been demonstrated that by using a new Direct Print Additive Manufacturing (DPAM) process of Fused Deposition Modeling (FDM) of plastic and micro-dispensing of pastes and inks, we can 3D print single and multi-mode optical fibers in a controlled manner such that compact, 3-dimensional optical interconnects can be printed along non-lineal paths. We are FDM printing the core materials from a plastic PMMA material. We are dispensing a urethane optical adhesive as the core material. These materials are available in many different refractive indices. During numerical simulations of these fibers, we were able to show through manipulation of the refractive indices of the core and cladding that we can also improve the bend performance of our fibers. As a result, they can perform better as an interconnect in tight routings between components as long as the interconnect fiber distances remain less than 1 meter. Fibers have been fabricated with diameters between 77 and 17 µm across an air gap with a surface roughness of less than 450 nm and cladded and tested with transmission rates of about 46%. 12 µm fibers have successfully been fabricated on a cladded surface as a proof of concept to test the small diameter and 3D shaping capability of this process.

The primary intention behind performing this thesis is to identify possibilities of implementing Metal Additive Manufacturing (MAM) in automotive industries in spare part manufacturing. This project tries to analyse the differences between conventional and contemporary manufacturing techniques. The industrial partner we worked with, Frauenthal Gnotec AB, specializes in traditional manufacturing techniques for making automobile spare parts primarily by stamping. Hence, a large building area is required to store the die and materials. Automobile spare parts are manufactured by demand. The organization has to have the die and material ready to go, forcing it to expand its inventories, workforce, and transportation, causing substantial financial liabilities.  The projects include a wide range of information from the different scientific articles, Journals, and consultations with AM services, Professors, and Technicians. The thesis studied the various available options in MAM and compared its specification with our client's requirements. The project estimates the cost, time for printing the components, thermo-mechanical properties, and structural properties of the component and its feasibility.   The project helped us put our theoretical knowledge about MAM into practice. It was very significant for us to have the opportunity to work with Frauenthal Gnotec AB, one of the leading automobile spare parts manufacturers in Sweden. Examine and evaluate their manufacturing and production strategies, which was very helpful for us in determining the efficacy of our efforts. Our scientific study, based on various simulations, optimizations, mechanical tests, and cost estimates, found MAM to be a promising future technology for the automotive industry.

Rapporten behandlar ett kandidatarbete i maskinteknik som utfördes tillsammans med Evomatic AB i Karlshamn. Syftet med detta examensarbete var att genom inlärda kunskaper under utbildningen utveckla och generera en lösning som möjliggör automatiskt utbyte av gripfingrar på ett gripdon som används i ett av Evomatics automatiserade robotsystem.  Genom en behovsanalys togs en kravspecifikation fram tillsammans med företaget som innehåller de krav och önskemål som företaget ställer på produkten. Kravspecifikationen beskriver specifikt och detaljerat de krav som ställs på produkten, i vårt fall var de främsta kraven att produkten skulle motstå ett visst vridmoment och hålla sig inom måtten för de anslutande delarna, huvudkravet var att produkten helt automatiserat utföra sin arbetsuppgift.  Efter att ha identifierat kundbehovet samt etablerat kravspecifikationen genomfördes en konceptgenerering där ett antal olika lösningskoncept togs fram genom brainstorming och brainwriting. De för- och nackdelar med respektive koncept ställdes mot varandra i en konceptsållningsmatris, för att tydliggöra slutsatsen om vilket koncept som var mest lämpligt och praktiskt genomförbart.  Det valda konceptet vidareutvecklades och tillverkades genom bl.a 3D-printing för att sedan genomgå ett funktionstest för att tydligt visa dess svagheter och styrkor i praktiken. Funktionstestet gav ett nära önskvärt resultat med bra respons från intressenten.  Slutsatsen som drogs utifrån det resultat som testet genererade var att konceptet i helhet fungerar som tänkt, med utrymme för förbättringar som uppmärksammades under testningstillfället. Dessa förbättringar implementerades i en slutlig version av konceptet för att möjliggöra framtagning av prisbild och jämförelse mot tidigare lösning. / This report represents a final degree project in mechanical engineering which was performed in cooperation with Evomatic AB, located in Karlshamn. The purpose of this thesis was to, through the knowledge learned during the education, develop and generate a solution that enables the automatic exchange of gripper fingers on a gripper unit used in one of Evomatic´s automated robot systems.  Through a needs analysis, a specification of requirements was generated together with the company, containing the requirements and wishes of the solution. This specification describes the requirements of the product in detail, in our case the main requirements were that the product should withstand a certain amount of torque, stay within the dimensions of the connecting components, but the main requirement was that the product would successfully perform its task automatically.  After having identified the customer need and established the specification of requirements, a concept development process was carried out where a number of different ideas were developed through brainstorming and brainwriting. The pros and cons with each concept were contrasted in a concept screening matrix, in order to clarify the conclusion of which concept was most suitable and practically feasible.  The chosen concept was further developed and manufactured through, among other things, 3D printing and then underwent a functional test to clearly show its weaknesses and strengths in practice. The functional test gave a close to desirable result with a good response from the company. Conclusively, the result generated by the test showed that the concept filled its function and purpose, with room for improvement, which was noted during the testing. These improvements were implemented in the final version of the concept as a 3D-model, to make it possible to produce a price point compared to the previous solution used.

Self-oscillating synthetic vocal fold (VF) models are often used to study human voice production. In this thesis, a method for fabricating multi-layer self-oscillating synthetic VF models using silicone 3D printing is presented. Multi-material 3D printing enables faster fabrication times with more complex geometries than traditional casting methods and builds a foundation for producing VF models with potentially more life-like geometries, materials, and vibratory characteristics. The printing method in this study used a custom dual extruder and slicing software to print UV-curable liquid silicone into a gel-like support matrix. The extruder was fabricated using high-torque stepper motors with high resolution leadscrews for precise extrusion and retraction. The custom slicing software accounted for challenges with printing a low-viscosity uncured silicone and was capable of allowing the user to visually observe the effects of print settings on print paths before finalizing the g-code. Three validation tests were conducted to demonstrate the 3D printer’s ability to print ultra-soft silicone with the desired range of stiffness, change between materials quickly, and print a material stiffness gradient. Two types of VF models were printed in this study, a previously-designed model with multiple distinct layers (“EPI” model), and the same model but with a vertical stiffness gradient (VSG) in the superficial lamina propria layer. The EPI model was chosen to demonstrate the ability to 3D print a multi-layer model, and the VSG model was chosen to demonstrate the ability to print multi-material VFs with geometric and material properties that are difficult to fabricate using traditional casting methods. Sixteen VFs (i.e., eight pairs) of each model type were printed, and their vibratory responses were recorded, including onset pressure, frequency, and glottal width. A micro-CT scanner was used to evaluate the external geometric accuracy of the models. One-centimeter cubes were 3D printed and tensile tested to characterize the material properties of each set of VF models. The material and phonatory properties of both the EPI and VSG VF models were found to be comparable to human data and to previous data acquired using synthetic VF models fabricated via other methods. In this thesis, the 3D printing methodology is summarized, the setup and results of the validation and VF model tests are reported and discussed, and recommendations for future work are provided.

Non-planar additive manufacturing (AM) technologies, such as microextrusion 3D printing processes, offer the ability to fabricate conformal electronics with impressive structure and function on curvilinear substrates. Although various available methods offer conformal 3D printing capability on objects with limited geometric complexity, a number of challenges remain to improve feature resolution, throughput, materials compatibility, resultant function and properties of printed components, and application to substrates of varying topography. Hence, the overall objective of this dissertation was to create new non-planar AM processes that are compatible with personalized and anatomical computer-aided design workflows for the fabrication of conformal electronics and form-fitting wearables. After reviewing the current state of knowledge and state of the art, significant challenges in non-planar AM have been identified as: 1) limited non-planar AM path planning capability that synergizes with personalized or anatomical object surface modification, 2) limited approaches for printed and non-printed component integration on non-planar substrates. To address these challenges, a template-based reverse engineering workflow is proposed for conformal 3D printing electronics and form-fitting wearable devices on anatomical structures. This work was organized into three complementary tasks that enhance non-planar AM capabilities: 1） To achieve anatomical tissue-sensor integration, 3D scanning-based point cloud data acquisition and customized 3D printable conductive ink are proposed for capturing the topographical information of patient-specific malformations and integrating conformal sensing electronics across anatomical tissue-device interface. 2） To fabricate conformal antennas on flexible thin-film polymer substrates, a versatile method for microextrusion 3D printing of conformal antennas on thin film-based structures of random topography is proposed to control the ink deposition process across the curvilinear surfaces of freeform Kapton-based origami. 3） To simplify the fabrication process of form-fitting wearable devices with fiber-based form factors and self-powered capability, an innovative 3D printing process is proposed to achieve coaxial multi-material extrusion of metal-elastomer triboelectric fibers. By developing new advanced non-planar printing processes and conformal toolpath programming strategies, the utility of non-planar AM could be further expanded for fabricating various personalized implantable and wearable multi-functional systems, including novel 3D electronics. In summary, this work advances capability in additive manufacturing processes by providing new advances in multi-material extrusion processes and personalized device design and manufacturing workflows. / Doctor of Philosophy / The ability to assemble electronic devices on three-dimensional objects with complex geometry is essential for developing next-generation wearable devices. Additive manufacturing processes, commonly referred to as 3D printing, now offer the ability to fabricate conformal electronics on surfaces and objects with non-planar geometry. This dissertation aims to expand non-planar 3D printing capabilities for applications to objects with anatomical or personalized structures, such as patient-specific malformation and origami. The proposed methods in this dissertation are focused on addressing challenges, such as the acquisition of object 3D topographical data, material selection, and tool path programming for objects that exhibit anatomical geometry. The utility of the proposed methods is demonstrated with practical applications to 3D-printed conformal electronics and wearable devices for monitoring human behavior and organ healthcare. This dissertation contributes to improving manufacturing capability and outcomes of 3D-printed form-fitting wearable and implantable devices. Future work may emphasize developing biocompatible functional ink and toolpath programming algorithms with real-time adaptation capability.

In this paper, a novel approach is utilized to investigate the deformation mechanisms at the microstructural level in 3D printed alloys. The complex in-situ heat treatments during 3D printing leaves a unique and complicated microstructure in the as-built 3D printed metals, particularly alloys. The microstructure is made of a hierarchical stacking of some interconnected geometrical shapes, namely meltpools, grains, and cells. These are connected to each other by boundaries that might have different element compositions, and consequently, material properties, compared to the interior region of each geometrical unit. Deformation mechanisms in this microstructure are still highly unexplored, mainly because of the challenges on the way of performing experiments at the micrometer length scale. In this work, we establish an image processing framework that directly converts the SEM images taken from the microstructure of 3D printed 316L stainless steel alloys into CAD models. The model of the complicated microstructure is then scaled up, and the scaled model is 3D printed using polymeric materials. For 3D printing these samples, two polymers with contrasting mechanical properties are used. Distribution of these two polymers mimics the arrangement of soft and stiff regions in the microstructure of 3D printed alloys. These representative samples are subjected to mechanical loads and digital image correlation is utilized to investigate the deformation mechanisms, particularly the delocalization of stress concentration and also the crack propagation, at the microstructural level of 3D printed metals. Besides experiments, computational modeling using finite element method is also performed to study the same deformation mechanisms at the microstructure of 3D printed 316L stainless steel. Our results show that the hierarchical arrangement of stiff and soft phases in 3D printed alloys delocalizes the stress concentration and has the potential to make microstructures with significantly improved damage tolerance capabilities. / Master of Science / Many researchers have studied the impacts of laser parameters on the bulk material properties of SLM printed parts; few if any have studied how these parts break at a microstructural level. In this work we show how SLM printed parts with complex microstructures including grains, meltpools, and cells, deform and break. The cellular network that occurs in some SLM printed parts leads to a multi-material hierarchical structure, with a stiff network of thin boundaries, and a bulk "matrix" of soft cell material. This leads to similar properties as some composites, whereby the stiff network of cell boundaries leads to increased damage tolerance. We show both computationally through finite element analysis, and experimentally through multi-material 3D fabrication, that the microstructure leads to increased crack length in failure, as well as lower toughness loss and strength loss in the event of a crack. Essentially, the complex nature of the formation of these parts (high heating and cooling rates from laser melting) leads to a beneficial microstructure for damage tolerance that has not been studied from this perspective before.

Synthetic, self-oscillating vocal fold (VF) models are physical models whose life-like vibration is induced and perpetuated by fluid flow. Self-oscillating VF models, which are often fabricated life-size from soft silicone elastomers, are used to study various aspects of voice biomechanics. Despite their many advantages, the development and use of self-oscillating VF models is limited by the casting process used to fabricate the models. Consequently, this thesis focuses on the development of 3D printing processes for fabricating silicone VF models. A literature review is first presented which describes three types of material extrusion 3D printing processes for silicone elastomers, namely direct ink writing (DIW), embedded 3D printing, and removable-embedded 3D printing. The review describes each process and provides recent examples from literature that show how each has been implemented to create silicone prints. An embedded 3D printing process is presented wherein a set of multi-layer VF models are fabricated by extruding silicone ink within a VF-shaped reservoir filled with a curable silicone support matrix. The printed models successfully vibrated during testing, but lacked several desirable characteristics which were present in equivalent cast models. The advantages and disadvantages of using this fabrication process are explored. A removable-embedded 3D printing process is presented wherein shapes were fabricated by extruding silicone ink within a locally-curable support matrix then curing the silicone ink and proximate matrix. The printing process was used to fabricate several geometries from a variety of silicone inks. Tensile test results show that printed models exhibit relatively high failure strains and a nearly isotropic elastic modulus in directions perpendicular and parallel to the printed layers. A set of single-material VF models were printed and subjected to vibration testing. The printed models exhibited favorable vibration characteristics, suggesting the continued use of this printing process for VF model fabrication. A micro-slicing process is presented which is capable of creating gcode for 3D printing multiple materials in discrete and mixed ratios by utilizing a previously-sliced single-material shape and a material definition. An important advantage of micro-slicing is its ability to create gcode with a mixed-material gradient. Initial test results and observations are included. This micro-slicing process could be used in material extrusion 3D printing

Optical resonators are structures that allow light to circulate and store energy for a duration of time. This work primarily looks at the fabrication, characterization, and application of whispering gallery mode microresonators and the analysis of organic photonic crystal-like structures and simulation of their resonant effects. Whispering gallery mode (WGM) microresonators are a class of cylindrically symmetric optical resonator which light circulates around the equator of the structure. These resonators are named after acoustic whispering galleries, where a whisper can be heard anywhere along the perimeter of a circular room. These optical structures are known for their ultra high Q-factor and their low mode volume. Q-factor describes the photon lifetime in the cavity and is responsible for the energy buildup within the cavity and sharp spectral characteristics of WGM resonators. The energy buildup is ideal for non-linear optics and the sharp spectral features are beneficial for sensing applications. Characterization of microbubble resonators is done by coupling light from a tunable laser source via tapered optical fiber into the cavity. The fabrication of quality tapered optical fiber on the order of 1-2 μm is critical to working on WGM resonators. The measurement of Q-factors up to 2x10⁸ and mode spectra are possible with these resonators and experimental techniques. This work focuses on microdisk and microbubble WGM resonators. The microdisk resonators are fabricated by femtosecond laser micromachining. The micromachined resonators are fabricated by ablating rotating optical fiber to generate the disk shape and then heated to reflow the surface to improve optical quality. These resonators have a spares mode spectrum and display a Q factor as high as 2x10⁶. The microbubble resonators are hollow microresonators fabricated by heating a pressurized capillary tube which forms a bubble in the area exposed to heat. These have a wall thickness of 2-5 μm and a diameter of 200-400 μm. Applications in pressure sensing and two-photon fluorescence of dye in microbubble resonators is explored. Photonic crystals can have engineered resonant properties by tuning photonic band gaps and introducing defects to create cavities in the photonic structure. In this work, a natural photonic crystal structure is analyzed in the form of diatoms. Diatoms are a type of phytoplankton which are identified by unique ornamentation of each species silica shell, called a frustule. The frustule is composed of a quasi-periodic lattice of pores which closely resembles manmade photonic crystals. The diatom frustules are analyzed using image processing techniques to determine pore-to-pore spacing and identify defects in the quasi-periodic structure which may contribute to optical filtering and photonic band gap effects. The data gathered is used to simulate light propagation through the diatom structure at different incident angles and with different material properties and to verify data gathered experimentally.

The past decade spotlighted a trend, which is that of individual users taking the role of innovators and physically creating their own products by explooting model additive manufacturing techniques. This trend emphasized the need for facilities able to serve as a platform for passionate makers to share knowledge, meet others and provides opportunities to realize their ideas. One of these platforms is Karlskrona Makerspace (KMS). KMS is located at Blekinge Institute of Technology (BTH) and provides 3D printing service, CNC milling machine and other facilities to help companies and individuals build physical prototypes. The purpose of this thesis is to expand the business of KMS and offer their service to more people. The study collects customer needs from potential KMS customers and aims at obtaining a viable business model after ranking risks. The main methodology used for building a business model is Running Lean Methodology to clear up complex associations in a business. The result shows that the business model identifies target customers, and clarifies the solutions to increase funding for KMS.