| Abstract: | A total of 90.5% of medical device sterilization is performed using Ethylene oxide (EtO) and gamma irradiation, while less than 5.5% incorporates accelerator technology (electron beam and X-ray). However, the government, public, and industry are trying to transition from EtO and gamma to accelerator technology with its advanced development and ease of use. Meanwhile, dielectric barrier discharge (DBD) plasma-based technology has been explored as a promising sterilization method since hydrogen peroxide gas plasma was marketed in the U.S. in 1993. Although DBD plasma is known for its promising characteristics, such as low temperature, high biocompatibility, low capital expenditures, point of use, small scale, etc., it still requires further in-depth research as a sterilization method. Driven by the concerns and uncertainties associated with accelerator and DBD plasma technology, this dissertation demonstrates that e-beam and X-ray are alternatives to gamma and determines the feasibility of the application of DBD plasma and e-beam on personal protective equipment (PPE) sterilization. An extensive literature review serves as support, focusing on the post-treatment effect of ionizing radiation and low-temperature plasma on polymers, especially the chemical reactions and material property changes. Experiments in this dissertation focus on a total of 27 representative medical devices, polymers, and PPEs, which were treated under ionizing radiation at doses from 10 kGy-80 kGy (e-beam, X-ray, and gamma) and DBD plasma-based mobile trailer reactor with an ozone dose of 700 ppm-min to 50000 ppm-min. Each process recipe utilized three to six repetitions, ensuring a confidence interval level of 80% to 95%. Discoloration, surface characterization, and mechanical and functionality testing were performed, and over ~5000 data points were collected and analyzed. Most results from a direct comparison among three ionizing radiation methods on samples revealed ignorable dependence on modality and sterilization-level dose (15 kGy-30 kGy), demonstrating that e-beam and X-ray are viable alternatives to gamma. Mechanical property deterioration and discoloration were only observed at a dose over sterilization level. Function degradation induced by e-beam was only detected in a polyethylene-made water pump, which was likely the result of the higher actual delivered dose of e-beam due to the worse dose uniformity compared with gamma. The overall results from DBD plasma-treated PPE indicated no mechanical and functionality degradation in PPE, with N95 respirators maintaining over 95% filtration efficiency. However, e-beam-treated PPE showed a decrease in filtration efficiency from >95% to 64% due to the loss of charge. This dissertation confidently concludes that e-beam and X-ray are excellent replacements for gamma, and DBD plasma-based technology is promising as an advanced sterilization approach, while further research focusing on PPE sterilization via e-beam is certainly necessary. The electronic version of this dissertation is accessible from https://hdl.handle.net/1969.1/198721 |
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