(Georgia Institute of Technology, 2018-05)
Adstedt, Katarina
The ability of atomic layer deposited (ALD) metal oxide films to serve as protective, encapsulating barriers for biological implants is determined through testing the corrosion resistance and degradation behavior of the films. Using plasma enhanced ALD (PE-ALD), metal-oxides are deposited at 100 oC onto gold electrodes. Through MTT cell proliferation assay, the films are determined to be cytologically compatible and will not cause harm to the implant host. Using electrochemical impedance spectroscopy (EIS), the films establish their relative chemical stabilities within three different biological environments, phosphate buffer solution (PBS), simulated sweat and simulated saliva. The resulting data from the EIS measurements demonstrates the rate of degradation for the four respective films and exhibits which films are best suited as protective barriers for biological implants. ALD Al2O3 is not suitable as an encapsulating layer as it demonstrates no corrosion resistance. Within PBS, ALD TiO2 establishes itself as the most stable film barrier while within simulated sweat and saliva ALD ZrO2 is the most chemically stable. The viability of ALD films in biological solutions and their enhanced corrosion resistances opens up the possibility for a new class of materials that can be used for the protection of bioimplants and wearable devices.
(Georgia Institute of Technology, 2008-07-07)
Averett, Rodney Dewayne
The objective of the current research was to contribute to the area of mechanics of composite polymeric materials. This objective was reached by establishing a quantitative assessment of the fatigue strength and evolution of mechanical property changes during fatigue loading of nanocomposite fibers and films. Both experimental testing and mathematical modeling were used to gain a fundamental understanding of the fatigue behavior and material changes that occurred during fatigue loading. In addition, the objective of the study was to gain a qualitative and fundamental understanding of the failure mechanisms that occurred between the nanoagent and matrix in nanocomposite fibers. This objective was accomplished by examining scanning electron microscopy (SEM) fractographs. The results of this research can be used to better understand the behavior of nanocomposite materials in applications where degradation due to fatigue and instability of the composite under loading conditions may be a concern. These applications are typically encountered in automotive, aerospace, and civil engineering applications where fatigue and/or fracture are primary factors that contribute to failure.