1,720,993 research outputs found
3D Printing of Flexible Ionic Liquid Gel Sensors
Get PDFThesis (Ph.D.)--University of Washington, 20233D printing has gained popularity due to the ability to fabricate complex structures from materials ranging from hard materials such as metal and concrete to softer materials including hydrogels and ion gels. Stretchable conductive materials have also attracted great attention due to their potential applications as strain sensors, wearable electronics, soft robotics, and medical devices. The fabrication of these materials with customized object geometries is desirable, but the methods to achieve them are still highly limited. 3D printing via vat photopolymerization can easily generate sophisticated object geometries, but there is still a significant need to print with materials that afford improved conductivity, mechanical properties, elastic recovery, and durability. Additionally, while 3D printing enables control over sensor design in multiple dimensions, customizability of a sensor toward different individual use cases is still limited because each sensorrequires a new design and manufacturing step. This thesis focuses on the development of ionic liquid gels as materials for conductive, elastomeric sensors. Chapter 1 serves as an introduction to 3D printing in general and discusses why ionic liquids are ideal materials for flexible devices. Chapter 2 discusses the application of ion gels as sensors and examines the effects of altering resin components on mechanical properties. Chapter 3 builds on these sensors by incorporating multiple ionic liquids into one structure. The difference in mechanical and elastic recovery properties produces shape transformation when strain is applied to the multi-material constructs. Lastly, chapter 4 seeks to improve the customizability of these ion gel sensors by incorporating dynamic bonds into the polymer networks to form covalent adaptable networks (CANs). The reversable covalent bonds introduced to the networks allow post-printing modification of the gels and facilitate fabrication of modular strain sensors
Solvent Exchange Method for Protein-based Bioplastics
No full textThesis (Master's)--University of Washington, 2025Additive manufacturing (AM) has seen significant growth in tissue engineering and medical device applications, with bioplastics emerging as preferred materials due to their biocompatibility and environmental sustainability. However, these bioplastic systems typically contain high water content, presenting significant challenges during the drying process. The high water content leads to anisotropic shrinkage, resulting in undesirable bending and warping of printed structures, which compromises their dimensional accuracy and functional properties. This study investigates the optimization of solvent exchange protocols using ethanol to produce dimensionally stable prints from bovine serum albumin (BSA) and poly(ethylene glycol) diacrylate (PEGDA) resin through vat photopolymerization. Our methodology focuses on establishing precise drying procedures that maintain the structural integrity of the printed components while preserving their mechanical properties. The results demonstrate that solvent-exchanged samples exhibited less than 30% volume reduction compared to control samples, indicating superior dimensional stability. Mechanical characterization revealed that the solvent exchange process did not significantly alter the material's mechanical properties, suggesting the preservation of its structural functionality. Thermal analysis was conducted to quantify the residual water content in solvent-exchanged samples, providing insights into the effectiveness of the dehydration process. Furthermore, complex printed structures subjected to the optimized solvent exchange protocol showed significantly reduced shrinkage, bending, and warping compared to untreated samples. This work establishes a robust methodology for producing high-resolution, dimensionally stable BSA-PEGDA prints suitable for consistent mechanical testing and complex structure fabrication, potentially advancing the field of biofabrication for tissue engineering and medical device applications
Polyether- and serum albumin-based hydrogels and bioplastics for bio-interfacing applications leveraging additive manufacturing
No full textThesis (Ph.D.)--University of Washington, 2024Additive manufacturing, commonly referred to as 3D printing, affords numerous advantages as an automated means of fabricating 3D objects with excellent design freedom and minimal waste. Despite remarkable progress over the past couple of decades toward making 3D printing technologies more capable and more accessible, there is still a need for more diverse functional materials for 3D printing. For example, in biomedical science and engineering, 3D printing has been used to fabricate anatomical models, medical devices, and tissue- and organ-like constructs comprising living cells. For many of these applications, there is a need for materials that better mimic or interface with the living systems in question. In tissue engineering and therapeutic delivery, hydrogels have shown great promise, as hydrated three-dimensional networks in which cells can be cultured or therapeutics can be encapsulated. Additionally, when naturally derived hydrogels are dehydrated, more functional or sustainable alternatives to petroleum-derived plastics can be obtained. These materials, which can be referred to as “bioplastics,” can be used to fabricate functional objects via 3D printing. This dissertation focuses on the design, synthesis, and application of functional hydrogels and bioplastics for additive manufacturing in the biomedical space. Chapter 1 contains a brief overview of 3D printing, hydrogels, and water-processable bioplastics, with an emphasis on their biomedical applications. Chapter 2 features a methodology that leverages additive manufacturing to fabricate coaxial nozzles for extrusion of hydrogel tubes toward modeling vascular endothelium. Chapter 3 highlights a highly tunable protein-based bioplastic platform for light-based (vat photopolymerization) 3D printing of functional objects. Chapter 4 describes dynamic hydrogels utilizing a protein-ligand interaction toward potential applications in therapeutic delivery or 3D bioprinting
Developing Catalytically Active Living Materials for Additive Manufacturing
No full textThesis (Ph.D.)--University of Washington, 2020Living materials are created through the embedding of live, whole cells into a matrix that can house and sustain the viability of the encapsulated cells. Through the cell immobilization process, their bioactivity (natural or engineered) can be harnessed for applications such as the production of high-value chemicals or biosensing environmental changes. While the idea of employing whole cell technologies is not new, the materials commonly employed in this space limit their implementation. Naturally derived polymeric materials often lack the robust mechanical properties needed for structural integrity of the materials, while many synthetic alternatives are either difficult to pattern or detrimentally influence cell viability and behavior. In this work, a novel platform of living materials is created, based on both commercially- available Pluronic F127 and a novel poly(alkyl glycidyl ether)-based triblock copolymer. The hydrogels that are afforded from these copolymers are stimuli-responsive, allowing for precise additive manufacturing of encapsulated cells into complex geometries. These stimuli responses include (1) a temperature response which allowed for facile processing of the material; (2) the shear response which facilitated the extrusion of the material through a nozzle; and (3) a UV-light induced polymerization which enabled the post-extrusion chemical crosslinking of network chains and the fabrication of robust printed objects. The mechanical properties of the living materials have been extensively characterized through the use of rheology. Additionally, the behavior of encapsulated cells has been explored through extensive microscopy of the living materials. The living materials developed herein have been demonstrated to effectively encapsulate yeast, bacteria, and algae while maintaining excellent cell viability for each microbial species. Through the use of extrusion 3D printing, precise spatial deposition of one or many cell types is made possible within a single printed construct. The printed living materials are shown to be effective to the on-demand and reusable production of high-value molecules, ranging from small molecules to peptides, through the use of both mono-culture or microbial consortia systems. Through the protection of embedded cells from preservation processes such as lyophilization, these Additively Manufactured Catalytically Active Living Materials (AMCALMs) can provide a platform for the sustainable generation of high-value compounds through repeated production phases
The Design of Functional Ion Gels and Hydrogels for Additive Manufacturing of Devices and Composites
Get PDFThesis (Ph.D.)--University of Washington, 2022Additive manufacturing (AM or 3D printing) involves selective deposition of materials in a layer-by-layer fashion to create customizable structures with precise 3-dimensional control. As AM evolved from a rapid prototyping process to a key driver towards the next industrial revolution, massive efforts have been made towards developing advanced printable materials. However, significant progress is still required to be made to push AM materials toward greater accessibility of the technology and functionality of the materials. One promising method to achieve this goal is 4D printing (4DP), which involves AM of materials that change their material properties (post-printing) in response to an external environmental stimulus. Stimuli-responsive materials have seen increased utility in AM of tissue engineering models, biomedical application, sensory and actuating devices. This thesis focuses on the development of stimuli-responsive hydrogels, ion gels, and ionoelastomers, for direct-ink-write (DIW) printing of composites, sensors, and actuators. Chapter 1 includes an overview of current stimuli-responsive materials for AM and their applications. Chapter 2 discusses the first demonstration of DIW printing of ion gel without the need of curing between layers or use of a nonsolvent, and 3D printing of soft sensors that have increased stretchability through both the material’s mechanical properties and the structural auxetic design. Chapter 3 explores incorporation of polymerizable ionic liquids to print shape memory ionoelastomers that can exhibit multi-directional bending upon stretch and release of the printed structure. Chapter 4 introduces a new method of post-print photocuring opaque hydrogel/particle composites via triplet fusion upconversion to overcome the limitations posed by traditional UV curing
Mechanical Studies of Bovine Serum Albumin-based Bioplastics in Additive Manufacturing
No full textThesis (Master's)--University of Washington, 2025Additive manufacturing (AM), or 3D printing, has revolutionized material fabrication by enabling customization, low-cost prototyping, and high efficiency. Vat photopolymerization, a widely used AM technique, uses light to selectively cure resins, offering high resolution and fast printing speed. However, most commercial resins are petroleum-based, exhibiting low biocompatibility and degradability, which limits their use in biomedical sustainability applications. This study investigates the mechanical properties of bovine serum albumin (BSA)-based bioplastics and methods to enhance the mechanical performance of BSA-based bioplastics. BSA-based bioplastics offer tunable mechanical properties that are comparable to commercial products. A dataset of 152 commercial resins from eight leading 3D printing companies was analyzed to create Ashby plots — in many cases, BSA-based bioplastics outperformed commercial resins in both strength and ductility while offering greater biodegradability. To further enhance the mechanical performance of these bioplastics, tannic acid (TA) and heat treatments were applied to methacrylated BSA (MA-BSA) materials. Swelling in TA followed by a denaturing thermal cure on printed structure was found to enhance the non-covalent bonding within the network and reduce rehydration, which increased Young’s modulus from 389 MPa to 757 MPa and improved ultimate tensile strength fivefold. With additional solvent exchange with ethanol, the Young’s modulus of MA-BSA bioplastics rose to 1.3 GPa, which made it comparable to those commercial bio-based resins. These advancements showcase BSA-based bioplastics as a promising, sustainable alternative for future biomedical 3D printing applications
Additive Manufacturing of Bovine Serum Albumin-based and Pluronic F127 Hydrogels and Bioplastics
No full textThesis (Ph.D.)--University of Washington, 2021Additive manufacturing (AM) has claimed its place as one of the key elements in the fourth industrial revolution, the automation and digitization of industry. By enabling one to rapidly fabricate and test any 3D structure over a range of length scales with limited expertise, AM is challenging the status quo of how things are invented and manufactured. However, the severe lack of materials that are compatible with AM limits its ability to disrupt the traditional manufacturing industry. To push the boundaries and drive forward innovation in manufacturing, new materials must be designed specifically for AM. This thesis explores the investigation of the printability of a library of synthetic inks for direct-ink write 3D printing and the development of globular protein-based resins for stereolithography. The inks for DIW are based on Pluronic F127, a triblock copolymer that forms temperature responsive, shear thinning hydrogels. Several rheological parameters that define a successful ink for DIW 3D printing are identified. Additionally, the development of a protein-based resin is reported, wherein the globular protein, bovine serum albumin, is modified and formulated into a photocurable resin for stereolithography. Several post-print treatments such as 120 °C thermal denaturation or tannic acid incubation were employed to tune the mechanical properties of the printed structures. This work demonstrates a set of resins and post-print treatments that can be used for a range of applications from biomedical devices to bioplastics
3D Printed Engineered Living Materials with Genetically Programmed Mechanical Properties and Bioproduction Performance for the Design of Functional Objects and Therapeutic Delivery Platforms
No full textThesis (Ph.D.)--University of Washington, 2024The synergy of synthetic biology and materials science yields innovative strategies to find alternative approaches for environmental, medical, and manufacturing challenges. Among these approaches, Engineered Living Materials (ELMs) stand out as a promising platform. ELMs, are a distinctive class of smart materials, which are synthetic living systems where genetically modified microorganisms are integrated into a polymer network, forming functional objects. The material properties and applications are determined by the cellular platform and the encapsulating polymer network. Nevertheless, gaps still exist in the seamless integration of biotic (cellular) and abiotic (polymer) components into a singular material, followed by their assembly into devices and machines. Herein, two different biocompatible polymer networks were developed including (i) a protein-based composite, bovine serum albumin (BSA) – poly (ethylene glycol) diacrylate (PEGDA), and (ii) a synthetic matrix comprising PEGDA-glycerol. These photocurable polymer networks were designed for processing ELMs in light-based 3D printing technologies. The relationships between embedded microorganisms and surrounding polymer matrices were investigated with respect to microbial viability, microbial proliferation behavior, bioproduction capacity, and mechanical properties of ELMs. Subsequently, the interactions between engineered microbial metabolites (L-dopa, betaxanthin, and proteinase A) and protein-based (BSA-PEGDA) polymer matrix were utilized to program mechanical stiffness and degradation time points as desired of 3D printed ELM objects. In an alternative strategy, the polymer concentration of the synthetic matrix (PEGDA-Glycerol) was adjusted to tune the toughness and moduli of 3D printed ELM bioreactors. Finally, an innovative approach toward ELMs for advanced drug delivery was developed using metabolically engineered probiotic strains and 3D printed medical stents. These ELM stents were designed to detect inflammatory biomarkers and initiate responses through the secretion of anti-inflammatory small molecules. This strategy presents a substantial opportunity for facilitating long-term, localized delivery
Designing Polymer Hydrogels for Extrusion-Based Additive Manufacturing
No full textThesis (Ph.D.)--University of Washington, 2021Additive manufacturing (AM) technologies are expanding the boundaries of materials science and providing an exciting forum for interdisciplinary research. The ability to fabricate arbitrarily complex objects has made AM technologies indispensable in personalized healthcare, soft electronics, and renewable energy. At the intersection of AM technologies and materials chemistry are stimuli-responsive polymers, which change their chemical and physical properties in response to specific environmental cues. Stimuli-responsive polymer hydrogels, in particular, are seeing significant interest in extrusion-based AM for the fabrication of bespoke medical implants and tissue engineering. The responsiveness of these “smart” hydrogels makes them suitable for AM and provides functionality to the additively manufactured objects. The type of stimulus response, mechanical properties, and functionality of these hydrogels can be regulated through chemical transformations or incorporation of additives. This dissertation describes two fundamentally different approaches to formulating polymer hydrogels for extrusion-based AM. Chapter 1 provides a thorough introduction to AM and stimuli-responsive hydrogels, with emphasis on hydrogels that respond to changes in temperature and shear pressure. Chapter 2 and Chapter 3 describe chemical transformations to the end groups of synthetic block copolymers to afford changes in hydrogel temperature response, mechanical characteristics, and morphology. By contrast, Chapter 4 reports the collaborative development of a 3D-printable bioink based on cardiac decellularized extracellular matrix (cdECM). While Chapter 2 and Chapter 3 deal with molecular-level changes to wholly synthetic polymer systems, Chapter 4 deals with biopolymers derived from porcine cardiac cells that are combined with synthetic additives. The two approaches offer contrasting strategies for the design of polymer hydrogels for AM
Light-Based Additive Manufacturing of Functional Gels via Thiol-ene Chemistry
No full textThesis (Ph.D.)--University of Washington, 2025Additive manufacturing (AM) is an ever-growing field that has benefited several industrial sectors including healthcare, aerospace, dentistry, and construction. The hardware of AM has seen significant investment where there is currently a large variety of technologies, each with unique advantages for specific applications. Vat photopolymerization, one of the earliest forms of AM technology, has the specific advantage of printing small objects with high fidelity. Although the technologies for vat photopolymerization have been greatly improved from the initial invention, the chemistry available for light-based AM has mainly remained the same. This creates an opportunity for polymer scientists and engineers to develop new materials specifically designed for light-based AM. Currently, most commercial photocurable resins for vat photopolymerization are based on chain-growth polymerizations limiting the scope of possible monomers for AM. Introducing new chemistries into light-based AM could enable printing of new materials. Polymeric gels are a class of materials that have the potential for a wide range of applications such as sensors, engineered living materials, and biomedical applications. This thesis focuses on the development of ionogel and hydrogels that can be printed via thiol-ene chemistry. Chapter 1 includes an overview of vat photopolymerization, the chemistry available, and the benefits of thiol-X reactions for vat photopolymerization. Chapter 2 discusses the development of an ionic liquid resin that us curable by photobase generators that catalyze an anionic thiol-ene reaction. Chapter 3 introduces an allylated hyperbranched poly(glycerol) (HPG) and the effect of the hyperbranched structure which enables rapid photocuring at sub-stoichiometric quantities of thiol macromonomer. Chapter 4 builds on the HPG resin by exploring the capacity of the dried gels absorbing sufficient water form moisture to support microbial growth to enable minimally hydrated engineered living materials
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