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Item Development of Bio-based Wood Adhesive by Using Cellulose Nanofiber Reinforcement and Crosslinking Agent for Improved Bonding Strength(North Dakota State University, 2017) Oh, MyungkeunEngineered woods, plywood, particle board, and oriented strand board, are widely used as a low-cost wood replacement in many applications. Many of the currently used wood adhesives contain chemicals that are harmful to human health and the environment. Increasing environmental and human health concerns have made the development of safe bio-based adhesives a priority. In this study, two plant proteins, zein from corn and wheat gluten, were used to develop wood adhesives. To increase their bond strength, cellulose nanofibers were added to create nanocomposite adhesives and a crosslinking agent was also used. Single-lap shear test, flexural and internal bond tests were performed on dry and water-immersed samples to measure the bond strength. Fractured bond surfaces were studied using optical observation and scanning electron microscopy (SEM) to determine bond failure mechanisms. Thermal and chemical properties of the adhesives were evaluated using thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR), respectively.Item Manipulation and Isolation of Biomolecules Using Dielectrophoretic and Hydrodynamic Methods(North Dakota State University, 2021) Oh, MyungkeunNovel particle manipulation techniques are developed to separate, isolate, and control a wide range biomolecules from DNA to cells in complex solution such as whole blood. First, we show that integrating an insulating tip with dielectrophoresis allows us to trap, carry, reposition, and relocate nanoscale objects, which can be used as molecular tweezers without fouling, electrolysis, and joule heating issues associated with conventional dielectrophoretic methods. In addition, we find that two theoretical force calculations (Clausius-Mossotti model and counter ion fluctuation model) result in a factor of 2-40 difference, but the magnitude of both is 4 orders stronger than the thermal force, which is strong enough to manipulate objects in the medium. Second, we perform sedimentation and size-based particle separation methods in a microfluidic device configuration. Using polydimethylsiloxane and its high gas solubility, we demonstrate a sedimentation-based, blood cell separation method. To further isolate small biomarkers such as exosomes utilizing a deterministic lateral displacement principle, we fabricate nanoscale pillar structures on a silicon wafer using multiple nanolithography processes and explore possibilities for size-dependent particle separation on the device.