【作者】 刘笑；

【导师】 姜洪源；

【作者基本信息】 哈尔滨工业大学 ， 机械设计及理论， 2007， 硕士

【摘要】 近年来,为预防传染性疾病和生物恐怖袭击,在水、食物和临床样品中的低浓度病原体检测技术研究等方面,引起了人们重视。目前有多种技术用于粒子的控制与收集,其中应用最广泛的是基于电场机制的方法。生物学上所关心的对象都是微米或纳米级的粒子,而基于电场机制的粒子收集与分离方法尤其适合于这样的微小级粒子,随着微机电系统(MEMS, Micro-Electro-Mechanical Systems)微加工技术的不断发展,使微纳米级的微电极与微流体器件集成成为可能。交流电渗(AC EO, Alternating Current Electro-Osmotic)技术是一门新兴技术,它在粒子收集与分离方面具有很多优势,如输入信号电压低、不易产生气泡、所需样品少、能实现实时检测、不依赖粒子大小和电场梯度变化,容易与微芯片集成等,因此成为当前研究的一个热门课题。本文详细综述了交流电渗粒子收集的国内外研究状况,分析了交变电场下粒子的受力情况,阐述了交流电渗的产生机理,研究了其粒子收集的原理,并用格林函数法求得溶液中的电势数值解,计算出粒子收集的位置,给出了粒子收集位置计算式。以理论分析为基础,建立交流电渗相关的数学物理模型,利用有限元软件求解有关电场和流场的Laplace方程及Navier-Stokes方程,并进行仿真分析。综合考虑包括介电泳(DEP, Dielectrophresis)、重力和浮力的作用,得到了微通道内粒子的速度分布。同时分析了包括外加频率、电压,溶液的电导率等主要参数对粒子收集效果的影响,为实验研究提供理论基础。为验证理论研究的正确性,设计加工了硅衬底平行式对称微电极芯片,以去离子水稀释直径0.5μm的聚苯乙烯微球混合溶液为实验研究对象,施加交变电场,在荧光粒子显微镜下观察到粒子收集现象。通过改变施加信号、溶液参数等成功地观察到了不同参数下的粒子收集实验结果,验证了主要特征参数对粒子收集的影响。全文通过对交流电渗粒子收集基本理论的阐述,理论分析计算、建模仿真分析及实验研究,验证该文的相关理论,为进一步展开交流电渗粒子收集与分离研究奠定了理论与实验基础。更多还原

【Abstract】 Recently, considerable interest and effort have been devoted to the on-site detection of low concentration pathogens in water, food and clinical samples in order to deter infectious diseases and bioterrorism. There are many techniques used for manipulating or sorting particles, with a widely used method is electric-based method.Owning to the subjects with lengths of the order micrometer or nanometer, the force arose from electric-based machine is especially for collecting or separating them. With the development of the technology micro-machining in MEMS, it is possible that the microelectrode with the lengths of the order micrometer or nanometer be fabricated into micro-devices. AC EO is a new technology, which shows many advantages in collecting or separating micro-particles, such as low signal voltage, generating bubble not easily, small sample, real-time detection, independent of the size of particles also the grad of electrical field and integrating in microchip easily, so it becomes a hot research subject.This paper introduces the research of particles sorting by AC EO at home and abroad in detail, and the force on the particles is analyzed. The forming principle of AC EO is expounded and the theory of AC EO sorting particles is researched. The numerical value of potential in solution is solved by Green’s function method, while the position particles sorting by AC EO is worked out and the formulation is given.The mathematical physics model of AC EO is built on the base of theory. The Laplace equation about electrical and the Navier-Stokes equation about flow field are solved by finite element software. The velocity of particles in micro-channel is solved with considering the DEP and gravity force. The main factors which influence the particles sorting by AC EO, such as frequency, voltage, conductivity of the solution is studied, which provides theoretical basis for experimental research.The parallel symmetry microelectrode chip is designed and manufactured in order to validate correctness of the theories research. The experimental research object is polystyrene of 0.5μmdiameter. The polystyrene sorting by AC EO is seen with florescent microscope when applied AC signal. The experiment of particles sorting with different characteristic parameters is seen successfully by change the application signal, conductivity of the solution, which verifies the tendency influence of the main characteristic parameters to the particles sorting.The full text verifies the relevant theories in this thesis by expounding the basic theory of AC EO particles sorting, theoretical analysis calculation, modeling and simulation analysis and experiment research, which establish the theoretical and experimental basis for further particles sorting and separating by AC EO research.更多还原