<p>Structures with inherent shape change capabilities enable adaptive, efficient designs without the weight and complexity of external actuators and sensors. Morphing structures are found in nature: plants are able to achieve fast motion without muscular or nervous systems. For example, the Venus flytrap snaps to a closed state with spatially distributed curvatures in less than one second. In contrast, synthetic shape change has been limited by a trade-off between complexity and speed. Shape memory polymers (SMPs) can remember complex shapes, but morphing is slow and one-way. Multistability due to mechanical buckling is fast and reversible, but it has been limited to simple shapes. Furthermore, many examples of biological shape change follow logical patterns with mechanisms that selectively respond to environmental stimuli. This suggests that synthetic morphing structures may also lend themselves to alternative forms of sensing, memory, and logic.</p> <p><br></p> <p>In this research, we introduce a new method of using SMPs in combination with the hierarchical architectures of pre-strained multistable laminates to create switchable multistable structures (SMS). An SMS can remember multiple permanent shapes and reversibly snap between them. We use extrusion-based 3D printing to encode contrasting shape memory-based pre-strain fields in a bilayer. Above the SMP’s glass transition temperature, the SMS becomes compliant and remembers multiple encoded permanent shapes with fast snap-through between them. Below the transition temperature, the SMS regains its stiffness and is fixed in a single state. The geometric freedom of 3D printing enables the design and manufacture of bioinspired structures with complex pre-strain fields and deflections. The developed printing method is applied in multiple subsequent studies, including mechanical pixels, self-folding spring origami structures, and multistable structures printed with thermoset composite inks. </p> <p><br></p> <p>The highly nonlinear behavior of bistable, pre-strained structures makes their design difficult and nonintuitive. Generally, these structures are designed using a slow, iterative process with finite element analysis (FEA). We aim to solve the inverse optimization problem: start with target stable states and solve for the necessary pre-strain distributions. To this end, we develop and implement the switching tunneling method (STM) to design pre-strained,</p> <p>multistable structures. Instead of FEA, we leverage analytical solutions for gradient-based optimization. Tunneling allows for the efficient search of a design space which may contain multiple local and global minima. Switching enables us to take advantage of two different function transformations, depending on if the search is far from or close to a minimum. The STM is validated through FEA and experiments for both conventional and variable</p> <p>pre-strain bistable structures.</p> <p><br></p> <p>Structures designed to react to external conditions or events offer the opportunity to directly integrate sensing, memory, and computation into a structure. This concept is explored using metasheets composed of locally bistable unit cells, which display spatiotemporal mechanical sensing (mechanosensing) and memory. A unit cell consists of a bistable dome with a piezoresistive strip at the base; the resistance indicates the state of the dome. The mechanics of bistability offer inherent filtering and nonlinear signal amplification capabilities, tunable via geometric parameters. Metasheet arrays of these unit cells display distributed sensing capabilities, as well as hierarchical multistability.</p> <p><br></p> <p>We explore the use of time-dependent material properties combined with the mechanics of multistability to encode many unique values within a single mechanosensor unit cell, beyond binary memory. When the piezoresistive material is viscoelastic, cyclic loading causes cumulative changes in both the ground and inverted state resistances. Effectively, the metamaterial is able to count how many times an external force has been applied; this count is stored in the metamaterial’s intrinsic, measurable properties.</p> <p><br></p> <p>This work demonstrates the importance of incorporating memory concepts into structural design, which enables multistability with complex stable shapes, as well as spatiotemporal sensing and memory capabilities. Engineered systems require increasingly adaptive and responsive structures to improve efficiency. The incorporation of inherent memory and sensing enables the complex behaviors needed to interact with unstructured environments</p> <p>and biological features, a pressing issue for aerospace, soft robotics and biomedical devices. The methodology developed here to manufacture, design, and analyze multistable structures advances the state of the art and makes their implementation more practical.</p>

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The primary focus of this thesis is the study of visual development for worldbuilding, starting with creative writing and documentation and translating the written content into visual concepts in both 2D and 3D. This project includes an original narrative, setting, and characters and explores aspects of the visual development pipeline. The content below contains work in visual research, 2D character design, 3D character sculpting, 3D printing and assembly, hard-surface modeling, matte-painting, illustration, compositing, and heavy creative writing.

In this thesis, the successful fabrication of 3D-printed microfluidic devices will be discussed. Fabrication is performed with a low-cost commercially available stereolithographic 3D printer utilizing a custom PEGDA resin formulation tailored for low non-specific protein adsorption based on my colleagues' work [Rogers et al., Anal. Chem. 83, 6418 (2011)]. Horizontal microfluidic channels with designed rectangular cross sectional dimensions as small as 300 um wide and 150 um tall are printed with 100% yield, as are cylindrical vertical microfluidic channels with 300 um designed (334 um actual) diameters. Moreover, two different resins developed by our group are utilized in the process of 3D-printing which is the novel aspect about this thesis since other groups have not done research on this aspect of 3D-printing.

Biomarkers are measurable indicators of health status or disease state that can be used for diagnosis and may help guide patient treatment strategies. Enzyme-linked immunosorbent assays (ELISA) and other many clinical techniques currently used for measuring biomarker proteins lack sensitivity, demand high analysis cost, are often not well-suited for measuring multiple biomarkers in a single sample, and require long analysis times. Here, we demonstrate simple, low-cost 3D-printed flow-through devices with integrated electrodes modified with gold nanoparticles (AuNPs) for electrochemical immunoassays of S100B, a biomarker protein related to conditions like skin cancer and brain injuries. Flow-through devices are fabricated from photocurable-resin using a desktop digital light processing (DLP) projector-based 3D printer to produce 500-800 µm square cross-sectional fluidic channels. Threaded ports at the ends and center of the channel are included in the device design for connecting commercially available fittings for fluid delivery and integrating low-cost graphite electrodes for electrochemical biosensing.

The purpose of this study is to examine the position and use of an upper extremity prosthetic simulator on non-amputees. To see how a 3D printed prosthetic simulator can be optimized to serve the user correctly and accurately. In addition, this study examines the improvement of the Hosmer 5X Prosthetic Hook with the addition of newly designed trusses on to the prosthetic, as well as utilizing a new manufacturing method known as 3D printing. These topics are important because there is no standardized prosthetic simulator for schools and research facilities to use. Off the shelf prosthetic simulator cost upwards of $2000, often too expensive for early stage research. By optimizing the Hosmer 5X Prosthetic Hook with 3D printing, this new opportunity could allow amputees, from a range of income classes, to have access to a wide variety of prosthetics that are strong enough to support everyday living activities. A low-cost prosthetic that is easily distributable and accessible can give people a chance to regain their independence by giving them different options of efficient prosthetic devices, without having to spend so much. The devices in this project were design and analyzed on SOLIDWORKS, 3D scanned on the Artec Space Spider, and surfaced on Geomagic Wrap. Key results include developing a low-cost, robust prosthetic simulator capable of operating a Hosmer 5X Prosthetic hook, as well as developing a lighter version of the Hosmer 5X Prosthetic Hook that is more cost efficient and easily obtainable to the population around the world.

Tissue engineering is a dichotomy of scaffold-based and scaffold-free cultures. Scaffold-based cultures form highly organotypic structures but with low uniformity and throughput. Conversely, scaffold-free cultures create consistently sized and shaped cell aggregates with limited spheroid-like structure and function, thus restricting their use for accurate disease modeling. We hypothesized that combining aspects of each culturing format, we would produce highly organotypic structures of consistent size and shape for use in pulmonary modeling. First, to improve on culture consistency and output, we created a novel easily scalable, minimalistic design for a micropatterned hydrogel dish that increases reliability and efficiency in 3D cell culture. This dish design features three times more efficient media change relative to commercially available plates. Moreover, we discovered that formation of consistently sized and shaped cell aggregates depended on hydrogel stiffness. Second, we developed a biocompatible 3D printing resin using poly(ethylene glycol) diacrylate (PEGDA) monomer with avobenzone as the UV absorber instead of 2-nitrophenyl phenyl sulfide (NPS). The polymerized resin could be surface activated to promote cell adhesion. This resin could be used in high-resolution printing of miniature devices for microfluidic and nanofluidic cell culture and cell assays. Third, we show a unique improvement on current methods to produce organotypic aggregates via suspension culture. By using soluble non-gelling concentration of basement membrane (BM), we created an organotypic lung model from three stable cells representing epithelial, vascular, and fibroblast cell populations within 14 days of culture. We observed that soluble BM promotes emergence of lumina comparable to mammalian lung airspaces. Using hypoxia induction techniques, we provide evidence for formation of branching, perfusable vasculature in pulmonary aggregates supplemented with soluble BM. Aside from these structural traits, we observed increased proliferation, survival, and 3D growth of aggregates. These results were supported by proteomic studies. As proof of concept, we applied this method in modeling of lung fibrosis using bleomycin induction followed by testing one investigational antifibrotic drug. Our results demonstrate a novel 3D culture method that creates organotypic models from stable cell lines. We anticipate this technology to pioneer creation of novel suspension-based organoids fostering consistent, expedited 3D culture. In summary, these three technologies highlighted in this dissertation improved on the 3D culture status quo. We view these technologies to have the potential to expedite creation of patient-derived organoids for personalized drug screening using lung-on-a-chip assays.

[pt] O presente trabalho propõe um novo tipo de ligação entre perfis pultrudados que não exija furação do material, seja leve e fabricado por manufatura aditiva. Para isso, fez-se uma revisão do estado da arte no âmbito das ligações entre perfis de compósitos, abordando ligações parafusadas simples, cujos parafusos estão sujeitos apenas ao corte, bem como as ligações semirrígidas, que são menos contempladas pela literatura atual. Além disso, tratou-se do uso de otimização topológica em componentes mecânicos voltados à impressão 3D. Posteriormente, define-se a geometria básica do componente proposto e o respectivo modelo numérico adotado no processo de otimização topológica, expondo todas as condições de contorno, carregamento e otimização. A fim de verificar experimentalmente o comportamento do componente apresentado, ensaios momento-rotação foram realizados em três grupos, sendo um composto por exemplares com a geometria original básica e os demais por componentes otimizados (com e sem reforço). Por fim, foi observado que o caminho de fibras estabelecido foi coerente com as solicitações às quais o componente está submetido, haja vista a maior eficiência manifestada pelo aumento de resistência e rigidez por unidade de massa. A mesma constatação se aplica ao processo de otimização e ajuste. No mais, a utilização do reforço com fibras implicou numa maior repetibilidade na resposta mecânica da ligação. / [en] The current work proposes a new type of joint between pultruded profiles that does not require drilling, is lightweight and build by additive manufacturing. To accomplish that, a state of art review on pultruded profiles joints was carried, addressing simple bolted joints which have their bolts only subjected to shear, as well as semi-rigid joints. Besides, the use of topology optimization on 3D-printed mechanical components is also addressed. Posteriorly, the basic geometry of the proposed component is defined and its respective numeric model used within the topology optimization, presenting their boundary, load and optimization conditions. In order to experimentally verify the behaviour of the component, moment-rotation tests were carried in three groups, namely, the original geometry group, the simple optimized group and the reinforced optimized group. In the end, it was observed that the defined fibre path is consistent with the stresses acting within the component, regarding the greatest efficiency shown in terms of strength and stiffness per unit mass for the reinforced specimens. The same applies to the optimization and adjusting processes. Furthermore, the use of fibre reinforcement led to a greater repeatability of mechanical response.