Development of Low-temperature Sterilization Technique Using Microwave Plasma and Its Medical Application

本研究旨在开发一种新型的大体积微波等离子体低温灭菌技术，并将其应用于医疗领域。在2004财政年度，我们进行了实验，以澄清等离子体灭菌的机制，并研究在低温下提高快速灭菌特性的可能性。在2005和2006财政年度，我们使用体波等离子体对包裹的医疗器械进行了低温内部灭菌的实验验证，以确认导管等特定医疗设备的灭菌。在下文中，我们列出了本研究的主要成果。(1)氧等离子体灭菌机理的阐明：实验证实，氧自由基的刻蚀作用是氧等离子体灭菌的主要因素。而在氧气中没有观察到强的紫外发射， ...更多信息 等离子体中，结果表明紫外发射是氮等离子体中的主要因素，因为在290〜400 nm范围内存在多个强紫外发射。(2)通过微波等离子体的开关控制减少热效应：由于塑料医疗器械为非耐热材料，因此需要避免热效应。通过引入微波等离子体的时间调制操作，我们成功地将样品的温度降低到70 ℃以下。(3)体波等离子体产生实验：为了对包裹物品内部进行灭菌，我们进行了体波等离子体灭菌实验。我们确认血浆是在塑料瓶内产生的。采用脉冲微波等离子体对玻璃纸包裹的生物指示剂（萎缩芽孢杆菌）进行灭菌，灭菌时间为20 min。(4)OH自由基的影响：采用微波等离子体对模拟空气的氮氧混合气体进行灭菌，研究了水蒸气添加量对灭菌效果的影响。结果表明，水蒸气对提高杀菌速度起着重要作用。孢子细胞的解体可能是由于等离子体中产生的OH自由基所致。(5)结果总结：我们报道了16篇期刊论文，2本书，38篇国际会议论文集，132篇国内会议报告。目前已申请等离子灭菌相关国内外专利7项，其中等离子灭菌方法专利1项。少

In this research, we aimed at developing a novel low-temperature sterilization technique using large-volume microwave plasma and finally applying the results to the medical field. In the fiscal year 2004, we have carried out the experiments to clarify the mechanism of plasma sterilization and to study the possibility of improving the characteristics of rapid sterilization at low temperature. In the fiscal years 2005 and 2006, we have performed the experimental verification of low-temperature internal sterilization for the wrapped medical instruments using the volume-wave plasma in order to confirm the sterilization of specific medical equipments such as catheter. In the following, we listed the main results of the present research.(1) Clarification of the sterilization mechanism of oxygen plasma: It was experimentally confirmed that the etching effect due to the oxygen radicals was the main sterilizing factor in the oxygen plasma. While no strong UV emission was observed in the oxygen … More plasma, it was shown that the UV emissions were main factor in the nitrogen plasma, since there were several strong UV emissions in the range of 290〜400 nm.(2) Reduction of thermal effect by means of on-off control of microwave plasma: It is required to avoid thermal effect in the case of plastic medical instruments, because of non-heat resist materials. By introducing the time-modulated operation of microwave plasma, we succeeded to reduce the temperature of the samples less than 70 ℃.(3) Experiment of volume-wave plasma production: To sterilize inside the wrapped articles, we have carried out the sterilization experiment using the volume-wave plasma. We confirmed that the plasma was produced inside the plastic bottle. By using the pulsed-microwave plasma, we confirmed the sterilization of biological indicators (Bacillus Atrophaous) wrapped by glassine paper within 20 min.(4) Effect of OH radicals: We have investigated the effect of water vapor addition on the sterilization performance using the microwave plasma with air-simulated nitrogen-oxygen gas mixture. From the results, it was deduced that the water vapor played an important role on the improvement of sterilization speed. The collapse of spore cells might be attributed to the OH radicals generated in the plasma.(5) Summary of results: We reported 16 journal papers, 2 books, 38 proceeding of international conferences, and 132 presentations in the domestic meetings. We also applied 7 domestic and foreign patents relating with the present plasma sterilization, and we have taken one patent on the plasma sterilization method. Less