Materials Science, Biomedical engineering, Chemical engineering, 3D Printing, Elastomer, Hydrogel, Mechanical Properties, Polyurethane, and Tissue Engineering
Understanding the physical and chemical properties of biomaterials in rapid 3D printing could pave a way for the construction of complex structures with specific functionalities. Both the material conditions and printing techniques play crucial roles in modulating these properties. This dissertation was dedicated to answering the basic questions about how to engineer and improve the mechanical performance of rapidly 3D printed structure from synthesis and printing process. Three distinct groups of materials, namely plastic, soft hydrogels, and elastomeric polymers were used as case studies to reveal their relationships. Additionally, the toughening mechanism of networks with different mechanical properties was discovered and tested. These results could help future studies in rapid prototyping of medical devices, as well as adapting 3D printing in tissue engineering as a new direction.
Engineering, Biomedical engineering, 3D printing, Automation, Bioengineering, Engineering, Instrumentation, and Sensor development
We demonstrate a simple and inexpensive sensor capable of weighing microgram- scale objects in fluid. When objects flow through a glass tube that is vibrating at its resonance frequency, the frequency changes by an amount that is inversely proportional to the object’s buoyant mass. By measuring this frequency change, microgram objects can be weighed in fluid with nanogram-scale resolution. These sensors are easily fabricated, require no labels or tags, and are versatile, making them a valuable instrument for both in situ and laboratory measurements. They are fully automated and can measure any appropriately sized object in a wide range of biological, physical, and chemical applications. Using resonating glass tubes, we demonstrate the mass change detected in zebrafish (D. rerio) embryos as they are exposed to various toxicants, the water uptake and germination of dry seeds as they are put in water, and degradation rates in biomaterials in different fluid media.Aside from the experimental data from two separate resonator geometries, we also present simulations on other geometries that can be explored for these sensors. We explore the advantages and disadvantages in each geometry and potential sources of measurement error associated with the resonators. The simulations allow us to predict the resolution and the quality factor of the resonator before a prototype is developed.We took advantage of various rapid prototyping techniques, including 3D printing for developing these sensors. In this process, we discovered that 3D printed parts produce a toxic effect in zebrafish embryos. This observation led to a separate project, in which we assessed the toxicity of printed parts from two main classes of commercial 3D printers, fused deposition modeling and stereolithography. We used zebrafish embryos, a widely used model organism in aquatic toxicology and monitored them for rates of survival, hatching, and developmental abnormalities. We found that parts from both types of printers were measurably toxic, with STL-printed parts significantly more toxic than FDM-printed parts. We also developed a simple post-printing treatment (exposure to ultraviolet light) that largely mitigates the toxicity of the STL-printed parts. Our results call attention to the need for strategies for the safe use and disposal of 3D-printed parts and printer waste materials.
Materials Science, Mechanical engineering, Biomedical engineering, 3D Printing, Bioassay, ELISA, Fused Deposition Modeling, Manufacturing, and Stereolithography
Fabrication of a microfluidic ELISA assay can be a very time-consuming method, due to the curing process required for molded parts. This thesis examines Fused Deposition Modeling and Stereolithography as candidates for rapid prototyping microfluidic devices. Individual components of the device were designed on SolidWorks, and underwent several generations of revisions to address problems of air and fluid leakage. We present an automated ELISA assay device created using a combination of Fused Deposition Modeling and Stereolithography as a comprehensive demonstration of additive manufacturing capabilities, as well as the methodology used to create such a device. A detailed explanation on how to troubleshoot the fabrication process and machines is also discussed.