用于脉冲电场灭菌的微系统的研究

发布时间：2018-09-19 20:26

【摘要】：近年来，用水环境不断恶化，而人们对水质的要求越来越高，饮用水中微生物的杀灭也变得越来越重要。传统的灭菌方法，如化学灭菌法，会产生有毒副产物，难以满足人们的健康要求，进而出现了多种物理灭菌技术。其中电灭菌方法中的脉冲电场灭菌技术由于处理时间短、能效高、温升小、无化学毒副产物等优点，成为一种具有巨大发展潜力的非热灭菌技术。然而，传统的脉冲电场灭菌系统需要能提供几千伏甚至几十千伏高压的脉冲发生器，使得设备成本高，限制了其推广应用。为了解决这一问题，本文开展了用于脉冲电场灭菌的微系统的研究，通过电极间距的缩小可以大大降低所需脉冲电压。在装置研究的基础上，以大肠杆菌为实验对象，利用几百伏的脉冲，实现了高效灭菌。为了清楚了解脉冲电场杀菌操作的过程和为电脉冲杀菌微系统的研制做对照，本文先利用传统的脉冲电场灭菌系统进行实验研究。研究结果表明，无论是模拟循环水处理的脉冲灭菌系统，还是方波脉冲的静态处理系统，都需要几千伏电压才能获得较好的灭菌效果。随后，本文研制了一种适于脉冲电场灭菌的柔性微芯片。通过COMSOL软件仿真分析了平板-齿状（PCT）电极、交叉梳状（ICT）电极和对称齿状电极（SCT）三种电极结构，并加工了两种电极结构的芯片用于实验研究。利用聚酰亚胺基底加工制作了柔性芯片，并在此基础上制作了微处理室，，搭建脉冲电场灭菌微系统实验平台，并对多种影响灭菌的参数进行了研究。实验结果证明，电极结构会对灭菌效果造成影响，其中PCT结构比ICT结构更优，这与仿真结果相符合。在基于PCT结构的微系统中，200V方波脉冲作用于大肠杆菌悬液，就能获得很好的灭菌效果。同时，高场强、宽脉宽、长的处理时间、成分简单的缓冲液、处在早期生长状态的细菌都对灭菌效果有增强作用。此外，基于微芯片的处理室利用介电电泳力，可将细菌富集到高场强区域，进而获得更好的灭菌效果。最后，本文研制了静态和连续的微间隙平板电极处理室，并分别搭建脉冲电场灭菌微系统，进行相关的灭菌实验。实验表明：对于铜电极的静态灭菌系统，电压360V（电场20kV/cm），脉宽50μs，脉冲间隔200ms，50～100个脉冲的处理条件下，杀菌效果好；而对于铜电极的连续灭菌系统，电参数不变，流量控制在200μL/min左右，也获得了很好的灭菌效果。
[Abstract]:In recent years, the water environment is getting worse and worse, and the demand for water quality is becoming higher and higher, and the killing of microorganisms in drinking water becomes more and more important. Traditional sterilization methods, such as chemical sterilization, can produce toxic by-products, which are difficult to meet the health requirements of people, and many physical sterilization techniques have emerged. Because of the advantages of short treatment time, high energy efficiency, low temperature rise and no chemical by-products, the pulsed electric field sterilization technology in the electric sterilization method has become a non-thermal sterilization technology with great development potential. However, the traditional pulsed electric field sterilization system needs to provide several kilovolts or even tens of kilovolts high voltage pulse generator, which makes the equipment cost high, and limits its popularization and application. In order to solve this problem, the microsystem used in pulsed electric field sterilization is studied in this paper. The pulse voltage can be greatly reduced by reducing the electrode spacing. On the basis of the equipment research, the high efficiency sterilization was realized by using hundreds of volts of pulse in Escherichia coli. In order to understand clearly the process of pulsed electric field sterilization and to compare with the development of electric pulse microsystem, the traditional pulsed electric field sterilization system was used in this paper. The results show that both the pulse sterilization system of simulated circulating water treatment and the static treatment system of square wave pulse require several kilowatts of voltage in order to obtain better sterilization effect. Subsequently, a flexible microchip suitable for pulsed electric field sterilization was developed. Three kinds of electrode structures, plate-toothed (PCT) electrode, cross-comb (ICT) electrode and symmetrical toothed electrode (SCT), were simulated by COMSOL software. The chips with two kinds of electrode structures were fabricated for experimental study. A flexible chip was fabricated by using polyimide substrate, and on the basis of this, a micro-processing chamber was made, and an experimental platform of pulsed electric field sterilization microsystem was set up, and a variety of parameters affecting sterilization were studied. The experimental results show that the electrode structure will affect the sterilizing effect, and the PCT structure is better than the ICT structure, which is in agreement with the simulation results. In the microsystem based on PCT structure, a good sterilization effect can be obtained by using 200 V square wave pulse in Escherichia coli suspension. At the same time, high field strength, wide pulse width, long treatment time, simple composition of buffer, bacteria in the early growth state all have enhanced the sterilization effect. In addition, the microchip based processing room can enrich bacteria into high field area by using dielectric electrophoresis force, and obtain better sterilization effect. Finally, the static and continuous microgap plate electrode treatment chamber was developed, and the pulsed electric field sterilization microsystem was built, and the related sterilization experiments were carried out. The experimental results show that the sterilization effect is good for the static sterilization system of copper electrode under the conditions of voltage 360 V (electric field 20kV/cm), pulse width 50 渭 s, pulse interval 200 Ms ~ 100 pulse interval, while for the continuous sterilization system of copper electrode, the electrical parameters are not changed. The flow control is about 200 渭 L/min, and the sterilization effect is very good.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R123.1

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