The goal of this work is to develop and characterize a manufacturing process that is able to create metal matrix composites with complex cellular geometries. The novel manufacturing method uses two distinct additive manufacturing processes: i) fabrication of patternless molds for cellular metal castings and ii) printing an advanced cellular ceramic for embedding in a metal matrix. However, while the use of AM greatly improves the freedom in the design of MMCs, it is important to identify the constraints imposed by the process and its process relationships. First, the author investigates potential differences in material properties (microstructure, porosity, mechanical strength) of A356 — T6 castings resulting from two different commercially available Binder Jetting media and traditional 'no-bake' silica sand. It was determined that they yielded statistically equivalent results in four of the seven tests performed: dendrite arm spacing, porosity, surface roughness, and tensile strength. They differed in sand tensile strength, hardness, and density. Additionally, two critical sources of process constraints on part geometry are examined: (i) depowdering unbound material from intricate casting channels and (ii) metal flow and solidification distances through complex mold geometries. A Taguchi Design of Experiments is used to determine the relationships of important independent variables of each constraint. For depowdering, a minimum cleaning diameter of 3 mm was determined along with an equation relating cleaning distance as a function of channel diameter. Furthermore, for metal flow, choke diameter was found to be significantly significant variable. Finally, the author presents methods to process complex ceramic structure from precursor powders via Binder Jetting AM technology to incorporate into a bonded sand mold and the subsequently casted metal matrix. Through sintering experiments, a sintering temperature of 1375 °C was established for the ceramic insert (78% cordierite). Upon printing and sintering the ceramic, three point bend tests showed the MMCs had less strength than the matrix material likely due to the relatively high porosity developed in the body. Additionally, it was found that the ceramic metal interface had minimal mechanical interlocking and chemical bonding limiting the strength of the final MMCs. / Ph. D.

One of the major limitations in Fused Filament Fabrication (FFF), a form of additive manufacturing, is the lack of composites with superior mechanical properties. Traditionally, carbon and glass fibers are widely used to improve the physical properties of polymeric matrices. However, the blending methods lead to fiber breakage, preventing generation of long fiber reinforced filaments essential for printing load-bearing components. Our approach to improve tensile properties of the printed parts was to use in-situ composites to avoid fiber breakage during filament generation. In the filaments generated, we used thermotropic liquid crystalline polymers (TLCPs) to reinforce acrylonitrile butadiene styrene (ABS) and a high performance thermoplastic, polyphenylene sulfide (PPS). The TLCPs are composed of rod-like monomers which are highly aligned under extensional kinematics imparting excellent one-dimensional tensile properties. The tensile strength and modulus of the 40 wt.% TLCP/ABS filaments was improved by 7 and 20 times, respectively. On the other hand, the 67 wt.% TLCP/PPS filament tensile strength and modulus were improved by 2 and 12 times, respectively. The filaments were generated using dual extrusion technology to produce nearly continuously reinforced filaments and to avoid matrix degradation. Rheological tests were taken advantage of to determine the processing conditions. Dual extrusion technology allowed plasticating the matrix and the reinforcing polymer separately in different extruders. Then continuous streams of TLCP were injected below the TLCP melting temperature into the matrix polymer to avoid matrix degradation. The blend was then passed through a series of static mixers, subdividing the layers into finer streams, eventually leading to nearly continuous fibrils which were an order of magnitude lower in diameter than those of the carbon and glass fibers. The composite filaments were printed below the melting temperature of the TLCPs, and the conditions were determined to avoid the relaxation of the order in the TLCPs. On printing, a matrix-like printing performance was obtained, such that the printer was able to take sharp turns in comparison with the traditionally used fibers. Moreover, the filaments led to a significant improvement in the tensile properties on using in FFF and other conventional technologies such as injection and compression molding. / Doctor of Philosophy / In this work two thermoplastic matrices, acrylonitrile butadiene styrene (ABS) and polyphenylene sulfide (PPS), were reinforced with higher melting thermoplastics of superior properties called thermotropic liquid crystalline polymers (TLCPs). This was done so that the resulting filaments could be 3D-printed without melting the TLCPs. The goal of this work was to generate nearly continuous reinforcement in the filaments and to avoid matrix degradation, and, hence, a technology called dual extrusion technology was used for the filament generation. The temperatures required for filament generation were determined using rheology, which involves the study of flow behavior of complex fluids. Dual extrusion technology allows processing of the constituent polymers separately at different temperatures, followed by a continuous injection of multiple TLCP-streams into the matrix polymers. In addition, the use of static mixers (metallic components kept in the path of flow to striate incoming streams) leads to further divisions of the TLCP-streams which are eventually drawn by pulling to orient the TLCP phase. The resulting filaments exhibited specific properties (normalized tensile properties) higher than aluminum and contained fibers that were nearly continuous, highly oriented, and an order in magnitude lower in diameter than those of carbon and glass fiber, which are commonly used reinforcements. High alignment and lower fiber diameter are essential for printing smoother printed parts. The filaments were intended to be printed without melting the TLCPs. However, previous studies involving the use of TLCP reinforced composites in conventional technologies have reported the occurrence of orientation relaxation on postprocessing, which decreases their tensile v properties. Therefore, temperatures required for 3D printing were determined using compression molding to retain filament properties on printing to the maximum extent. On printing using an unmodified 3D printer, parts were printed by taking 180º turns during material deposition. Contrarily, the use of continuous carbon fibers required a modified 3D printer to allow impregnation during 3D printing. Moreover, the performance comparison showed that the continuous carbon fibers could not be deposited in tighter loops. The properties of the printed parts were higher than those obtained on using short fibers and approaching those of the continuous fiber composites.

This thesis proposes a new method for detecting malicious cyber-physical attacks on additive manufacturing (AM) systems. The method makes use of a physical hash, which links digital data to the manufactured part via a disconnected side-channel measurement system. The disconnection ensures that if the network and/or AM system become compromised, the manufacturer can still rely on the measurement system for attack detection. The physical hash takes the form of a QR code that contains a hash string of the nominal process parameters and toolpath. It is manufactured alongside the original geometry for the measurement system to scan and compare to the readings from its sensor suite. By taking measurements in situ, the measurement system can detect in real-time if the part being manufactured matches the designer's specification. A proof-of-concept validation was realized on a material extrusion machine. The implementation was successful and demonstrated the ability of this method to detect the existence (and absence) of malicious attacks on both process parameters and the toolpath. A case study for detecting changes to the toolpath is also presented, which uses a simple measurement of how long each layer takes to build. Given benchmark readings from a 30x30 mm square layer created on a material extrusion system, several modifications were able to be detected. The machine's repeatability and measurement technique's accuracy resulted in the detection of a 1 mm internal void, a 2 mm scaling attack, and a 1 mm skewing attack. Additionally, for a short to moderate length build of an impeller model, it was possible to detect a 0.25 mm change in the fin base thickness. A second case study is also presented wherein dogbone tensile test coupons were manufactured on a material extrusion system at different extrusion temperatures. This process parameter is an example of a setting that can be maliciously modified and have an effect on the final part strength without the operator's knowledge. The performance characteristics (Young's modulus and maximum stress) were determined to be statistically different at different extrusion temperatures (235 and 270 °C). / Master of Science

The overall goal of this research work is to enhance the capabilities of large-format, polymer material extrusion, additive manufacturing (AM) systems. Specifically, the aims of this research are to (1) Construct, and develop a robust workflow for, a large-format, robotic, AM system; (2) Develop an algorithm for determining and relaying proper rotation commands for 5 degree of freedom (DoF) multi-axis deposition; and (3) Create a method for printing a removable support material in large-format AM. The development and systems-integration of a large-format, pellet-fed, polymer, material extrusion (ME), AM system that leverages an industrial robotic arm is presented. The robotic arm is used instead of the conventional gantry motion stage due to its multi-axis printing ability, ease of tool changes for multi-material deposition and/or subtraction, and relatively small machine footprint. A novel workflow is presented as a method to control the robotic arm for layer-wise fabrication of parts, and several machine modifications and workflow enhancements are presented to extend the multi-axis manufacturing capabilities of the robot. This workflow utilizes existing AM slicers to simplify the motion path planning for the robotic arm, as well as allowing the workflow to not be restricted to a single robotic deposition system. To enable multi-axis deposition, a method for generating tool orientations and resulting deposition toolpaths from a geometry's STL file was developed for 5-DoF conformal printing and validated via simulation using several different multi-DOF robotic arm platforms. Furthermore, this research proposes a novel method of depositing a secondary sacrificial support material was created for large-format AM to enable the fabrication of complex geometries with overhanging features. This method employs a simple tool change to deposit a secondary, water-soluble polymer at the interfaces between the part and supporting structures. In addition, a means to separate support material into smaller sections to extend the range of geometries able to be manufactured via large-format AM is presented. The resultant method was used to manufacture a geometry that would traditionally be considered unprintable on conventional large-format AM systems. / Master of Science / Additive manufacturing (AM), also known as 3D printing, is a method of manufacturing objects in a layer-by-layer technique. Large-format AM is typically defined as an AM system that can create an object larger than 1 m3. There are only a few manufacturers in the world of these systems, and all currently are built on gantry-based motion stages that only allow movement of the printer in three principal axes (X, Y, Z). The primary goal of this thesis is to construct a large-format AM system that uses a robotic arm to enable printing in any direction or orientation. The use of an industrial robotic arm enables printing in multiple planes, which can be used to print structures without support structures, print onto curved surfaces, and to purt with curved layers which produces a smoother external part surface. The design of the large-format AM system was validated through successful printing of objects as large as 1.0x0.5x1.2 m, simultaneous printing of a sacrificial support material to enable overhanging features, and through completing multi-axis printing. To enable multi-axis printing, an algorithm was developed to determine the proper toolpath location and relative orientation to the part surface. Using a part's STL file as input, the algorithm identifies the normal vector at each movement command, which is then used to calculate the required tool orientation. The tool orientations are then assembled with the movement commands to complete the multi-axis toolpath for the robot to perform. Finally, this research presents a method of using a second printing tool to deposit a secondary, water-soluble material to act as supporting structures for overhanging and bridging part features. While typical 3D printers can generally print sacrificial material for supporting overhangs, large-format printers produce layers up to 25 mm wide, rendering any support material impossible to remove without post-process machining. This limits the range of geometries able to be printed to just those with no steep overhangs, or those where the support material is easily reachable by a tool for removal. The solution presented in this work enables the large scale AM processes to create complex geometries.

The importance of the aura, the metaphysical element that gives art, artifacts, and other objects of cultural heritage their authenticity, has been heavily contemplated ever since the publication of Walter Benjamin's "The Work of Art in the Age of Mechanical Reproduction." This thesis strives to add to this conversation and expand upon it by delving into the emergence of additive manufacturing, or what is more commonly known as 3D printing, and its relation to museums and other institutions that comprise the public humanities. This technology challenges the auratic properties of an exhibit by first digitizing it onto a computer by scanning it and then uploading this data to a 3D printer, which then proceeds to replicate the scanned exhibit down to incredibly fine details. For museums the possibility that 3D printed replicas, increasingly able to be indistinguishable from the original and capable of being produced in great numbers at ease, replacing their auratic exhibits is a very real possibility to consider. This thesis argues that some museums are responding by despatializing their exhibitions in order to uphold their auratic exhibits, while others are offsetting the potential loss by turning their exhibitions into tactile, multisensory experiences. Either option, which are not mutually exclusive, transforms the traditional museum. This thesis ultimately concludes that it's possible to reconcile the auratic exhibit with the 3D printed replica should these institutions properly adapt. Doing so will allow them to continue fulfilling their mission statements to preserve and promote the auratic exhibits well into the future. / Master of Arts

The hybridization of direct write (DW) and additive manufacturing (AM) technologies to create additively manufactured electronics (AME) has enabled the integration of electrical functionality to form multifunctional AM components. Current work in AME has demonstrated the integration of conductive traces into and onto geometries and form factors that are not possible through traditional electronics packaging processes. This has largely been accomplished by using AM and DW technology to deposit conductive inks to form interconnects on the surface of AM substrates or within multimaterial AM geometries. However, the requisite thermal post-processing and high resistivity of the conductive inks and the limitations in thermal and dielectric performance of printable substrates commonly used in AME restrict the capabilities of these parts. This thesis proposes an alternative process for the conformal deposition of low resistivity traces on additively manufactured all-aromatic polyimides (AM-PI) without the use of conductive inks. This is accomplished through the selective patterning of laser induced graphene (LIG), a porous 3D graphene fabricated via laser irradiation, onto the AM-PI. While the resultant LIG is conductive, its resistivity is further reduced by the electrodeposition of copper (Cu-LIG). In this thesis, the synthesis of LIG on AM-PI, thermally post processed to 240℃, 300℃, and 450℃, is demonstrated and characterized through sheet resistance measurements and Raman spectroscopy. AM-PI post-processed to 300℃ demonstrated the lowest resistivity LIG formation (13.8 Ω/square). The resistivity of Cu-LIG is compared to an industry standard silver ink (Micromax CB028) used in direct write hybrid manufacturing applications. Cu-LIG was found to have a measured resistivity (1.39e-7 Ω·m), two orders of magnitude lower than the measured resistivity of the CB028 silver ink (1.62e-5 Ω·m). Additionally, the current capacity of the Cu-LIG was demonstrated and Joule heating of the material was observed via IR thermography. Cu-LIG demonstrated no failure of conductive trace or substrate under 5A of current for 2 minutes, heating to a maximum recorded temperature of 76.3℃. Several multifunctional components were fabricated as case studies to further validate the process. Several small passive electronic devices (e.g., a heater and an interdigitated capacitor) are fabricated to demonstrate selective deposition of complex copper traces. The fabrication of an Archimedes spiral on a hemispherical substrate via Cu-LIG is completed to demonstrate the ability to use the process to fabricate conformal conductive traces. An LED circuit is fabricated on a face-center cubic AM-PI lattice which demonstrates multi-planar fabrication on geometrically complex 3D printed substrates. / Master of Science / The hybridization of direct write (DW) and additive manufacturing (AM) technologies to create additively manufactured electronics (AME) has enabled the fabrication of AM components which have electronic functionality. Current work in AME has demonstrated the integration of conductive traces into and onto geometries and form factors that are not possible through traditional electronics packaging processes. This has largely been accomplished through the deposition of conductive inks to form interconnects on the surface of AM substrates or within multimaterial AM geometries. However, these conductive inks require thermal post-processing temperatures which exceed the thermal performance of common AM substrates. The dielectric performance of AM substrates is also restrictive to the capabilities of these parts. This thesis proposes an alternative process for the conformal deposition of low resistivity traces on high performance additively manufactured all-aromatic polyimides (AM-PI) without the use of conductive inks. This is accomplished through the selective patterning of laser induced graphene (LIG), a porous 3D graphene fabricated via laser irradiation, onto the AM-PI. While the resultant LIG is conductive, its resistivity is further reduced by the electrodeposition of copper (Cu-LIG). In this thesis, the synthesis of LIG on AM-PI, thermally post processed to 240℃, 300℃, and 450℃, is demonstrated and characterized through sheet resistance measurements and Raman spectroscopy. AM-PI post-processed to 300℃ demonstrated the lowest sheet resistance LIG formation (13.8 Ω/square). The resistivity of Cu-LIG is compared to an industry standard silver ink (Micromax CB028) used in direct write hybrid manufacturing applications. Cu-LIG was found to have a measured resistivity (1.39e-7 Ω·m), two orders of magnitude lower than the measured resistivity of the CB028 silver ink (1.62e-5 Ω·m). Additionally, the thermal performance and current capacity of the Cu-LIG was demonstrated by observing resistive heating of the material under current load via IR thermography. Cu-LIG demonstrated no failure of conductive trace or substrate under 5A of current for 2 minutes, heating to a maximum recorded temperature of 76.3℃. Several multifunctional components were fabricated as case studies to further validate the process. A heater and an interdigitated capacitor are fabricated to demonstrate selective deposition of complex copper traces. The fabrication of an Archimedes spiral on a dome via Cu-LIG is completed to demonstrate the ability to use the process to fabricate conformal conductive traces. An LED circuit is fabricated on an AM-PI lattice which demonstrates multi-planar fabrication on geometrically complex 3D printed substrates.

The InsulPatch is a novel integrated patch-pump device used to deliver drugs, especially macromolecular drugs that are difficult to deliver through an oral pathway and that require transdermal delivery. The patch-pump is a promising replacement for conventional syringes and battery-powered pumps because it is slim, powerless, painless, and relatively inexpensive. The majority of this thesis focuses on the fabrication and testing of microfluidic devices for the delivery of insulin, which is a model drug that is widely used and needs to be delivered transdermally. In this thesis, we demonstrate the fabrication of the patch-pump, which includes an insect-mimetic microfluidic pump fabricated using photolithography and replica molding, and a microneedle array fabricated using 3D printing. The microfluidic pump is used to drive the fluid flow powered by pressurized air or the user’s pulse, and the microneedle array is used to inject the fluid through the skin painlessly. Using pressurized air-driven flow testing, we have tested the flow rate across microfluidic pumps of various flow channel widths over a range of physiologically relevant actuation frequencies and pressures. We have found that for the specific channel design we have been using, the flow rate generally positively correlates with the actuation pressure. For devices with wider flow channels, the flow rate generally negatively correlates with the actuation frequency, whereas the flow rate increases and then decreases with increasing actuation frequency for devices with narrower flow channels. This property of these devices is beneficial in insulin delivery because the demand for insulin is generally reduced in vigorous exercise (with elevated heart rate/actuation frequency) and increased in hypertension patients (with elevated blood/actuation pressure). A major future direction of the study is to test a wide range of device designs in a sample of human subjects by attaching the device onto the wrist and measuring the pulse-driven flow across the device. We can further change the channel design parameters of the device so that it will be ideal for insulin delivery. Using the ex vivo flow testing and human subject data, we can further tailor the device design to specific patients using a genetic algorithm-guided optimization based on the heart rate and blood pressure of the patient and the desired flow rate. We will also perform computational modeling using COMSOL Multiphysics to predict the flow across devices of different designs as well as to understand the physics behind the pulse-driven flow. Finally, a 3D-printed insulin reservoir will be incorporated into our patch-pump system for the storage of U-500 insulin. / M.S. / The InsulPatch is a slim, powerless device (“patch-pump”) that can be used to deliver drugs through the skin, especially designed for drugs that are difficult to deliver orally. The patch technology is a promising replacement for conventional injection using syringes and bulky battery-powered pumps. At this stage, the primary drug that our device aims to deliver is insulin, which generally needs to be delivered through the skin. In this thesis, we demonstrate how our patch-pump is made and how its performance is tested. The patch-pump has two parts: the microfluidic pump and the microneedle array. The microfluidic pump is fabricated using a technique called photolithography, in which a photosensitive polymer is selectively cured by UV light, and replica molding, in which the precursor of another polymer is poured on a mold and cured. The microneedle array is made using 3D printing and designed in such a way so that it can be readily connected to the microfluidic pump. The microfluidic pump is used to drive the fluid flow powered by the user’s pulse, and the microneedle array is used to inject the fluid through the skin painlessly. Through testing the flow across the microfluidic pump prototypes using pressurized air, we characterized the correlation between the flow rate of fluid across the device and parameters including the actuation pressure and frequency of the pressurized air as well as the width of the flow channel. Future directions of the study include testing the devices in human subjects to characterize pulse-driven flow across the devices, computational modeling of the devices, and further changes of the device design to optimize the performance of the device. We will also optimize the device design computationally to tailor the device design to specific diabetic patients. Finally, we will incorporate a 3D-printed insulin reservoir into our system for the storage of insulin solution. / Withhold all access to the ETD for 1 year / patent / I hereby certify that, if appropriate, I have obtained and submitted with my ETD a written permission statement from the ower(s) of each third part copyrighted matter to be included in my thesis or dissertation, allowing distribution as specified above. I certify that the version I submitted is the same as that approved by my advisory committee.

The first edition of a series holds value. It is a bookmark that holds a place in time that the artist can look back to and see the progress that led up to that point, as well as the continued progress that's been made after. Designing and creating a set of characters, bringing the main character through 3D modeling, and printing it has multiple uses in the industry. The techniques learned through this process have been used in toy design, stop-motion animation, museums, and medical applications. 3D printing is advancing and providing an opportunity to create high-definition models that can be reproduced quickly while maintaining their initial integrity. This paper will go through the model's design concept and how to execute it. It is also a culmination of all the traditional skills acquired from a fine art background combined with all the new skills learned in the digital media field. This project aims to create a cohesive set of 2D character concepts centered around the story By Command of the Prince Daniel (Nikolaevich, 1915). The main antagonist, Baba Yaga, was then brought through the 3D modeling process so she could be resin printed and turned into a collectible figurine. Descriptive character traits from her stories were reimagined while providing a unique approach to the design that still preserves the story's essence.

Preview image from Ariel Adam's Baba Yaga: Character Design and Collectible Figurine. / https://dc.etsu.edu/digitalmedia-culminating-experience-gallery/1000/thumbnail.jpg

The main objective of the research in this dissertation is to take advantage of unique materials, innovative designs, novel microfabrication techniques, and specialized characterization tools to develop a set of BioMEMS devices and systems further validated with electrical, interface, geometric, and multiphysics models to address unique biological problems emanating from ethical treatment of animals in drug discovery, biological translation, decentralization and personalization of healthcare. This set of devices is designed to interface with multi-sized biological constructs such as 3D cellular networks, viruses, and proteins. The first objective explored a 3D printing-based microfabrication technology to create 2.5D/3D microelectrodes to interface with cellular constructs such as tissues and organoids. Investigations were carried out on how surface roughness and printing parameters play a critical role in the electrical response of the system for in-vitro applications. Three different metallization strategies were investigated and modeled in order to define novel self-insulated 2.5 and 3D microelectrodes. The second objective centered around virus and microparticle detection using a novel combination of microfluidics and Wi-Fi optical detection. Microfluidics were created designing a multilayered system and processing various polymeric materials. The optical system was able to detect and wirelessly transmit information about the presence of viruses including COVID-19 Delta strain and microparticles in the 5 to 10 microns size. The last objective of the dissertation presented the microfabrication of a BioMEMS platform for electrophysiological characterization of Actin protein (smallest entity within the size spectrum). This platform combined interdigitated electrodes, PDMS soft lithography, and impedance and interface modeling to better understand Actin protein dynamics in bundles. This dissertation proposes innovative ideas to the current state of the art for emerging paradigms in the medical technology field involving rapid sensing and manipulating biological entities at various size scales: (proteins, DNA/RNA), (pathogens, virus), and (organoids, spheroids, assembloids).