集成惯性聚焦结构的粒子连续分离介电泳微流控芯片的研究

发布时间：2018-04-02 17:37

本文选题：惯性聚焦　切入点：介电电泳　出处：《中北大学》2017年硕士论文

【摘要】：随着微制造技术的发展,应用于生物学的集成流体、电场以及光学元件的芯片发展迅速。这些芯片充分利用不同的技术进行样品的制备以及分析。在样品制备方面,一种重要的技术就是粒子分离,其中介电电泳是一种不需要对粒子进行标记,对细胞无损伤,可同时对多细胞进行操作,而且还可以与其他技术相结合进而提高分离效率的方法。传统的介电泳分离方法多采用断续分离的方法,根据粒子的正负介电泳不同将一种粒子吸附在电极表面,通过流体的流动将未吸附的粒子冲走从而实现两种粒子的分离,该种方法所需时间长,需等粒子吸附完全之后才可以进行。其次,为提高分离的效率,避免目标粒子被冲走,需设置较高的电场,引起电热流的产生,影响分离效果。因此,本文设计了一种集成惯性聚焦结构的粒子连续分离介电泳微流控芯片,将惯性聚焦技术与介电泳分离技术相结合,实现粒子快速、高通量的连续分离。本文首先对惯性聚焦原理和介电泳粒子分离原理进行研究。由粒子在通道中的受力情况分析粒子聚焦的影响因素和粒子所受介电泳大小的影响因素。对聚苯乙烯小球、酵母菌细胞和NB4细胞的频率响应特性进行分析,确定不同粒子在芯片中的受力情况,分析其运动趋势。其次,根据粒子聚焦原理和分离原理设计芯片的结构。在通道入口侧壁设置梯形结构使经过的粒子受惯性升力的作用产生聚焦;通道底部光刻一组倾斜叉指电极产生非均匀电场,利用介电泳力和流体曳力的合力使不同的粒子发生角度不同的偏转进入不同通道,从而实现分离。利用Comsol Multiphysis软件对芯片内部电场进行仿真模拟,优化并确定芯片微通道的高度和叉指电极的宽度与间距。再次,加工制作了微流控芯片:根据芯片功能选取合适的材料,采用光刻工艺在ITO玻璃表面加工微电极,采用PDMS加工带有聚焦结构的微通道,并对芯片进行氧等离子键合,制成实验所需要的芯片。最后,搭建了实验平台,进行了粒子连续分离实验:首先,采用微尖电极分别测试聚苯乙烯小球、酵母菌细胞的临界频率,确定二者的分离频率,并对其进行断续分离;其次,采用设计的电极对聚苯乙烯小球和酵母菌细胞进行连续分离,分析流速、电压对二者分离的影响并且优化分离条件,实现二者的连续分离;最后,对酵母菌细胞、NB4细胞和聚苯乙烯小球、NB4细胞进行连续分离,并对实验的分离效率和分离纯度进行统计分析。
[Abstract]:With the development of microfabrication technology, microchips used in biology integrated fluid, electric field and optical components are developing rapidly.These chips make full use of different techniques for sample preparation and analysis.In sample preparation, one of the most important techniques is particle separation, in which dielectric electrophoresis is one that does not need to label particles, does not damage cells, and can operate on multiple cells at the same time.Moreover, it can be combined with other techniques to improve the separation efficiency.The traditional separation methods of dielectric electrophoresis usually adopt the method of intermittent separation. According to the positive and negative dielectric electrophoresis of particles, one particle is adsorbed on the electrode surface, and the unadsorbed particles are washed away by the flow of fluid to realize the separation of the two kinds of particles.This method takes a long time and can not be carried out until the particle adsorption is complete.Secondly, in order to improve the separation efficiency and avoid the target particles being washed away, it is necessary to set a higher electric field to cause the electrothermal current and affect the separation effect.Therefore, a microfluidic chip integrated with inertial focusing structure for continuous separation and dielectric electrophoresis of particles is designed, which combines the inertial focusing technology with the dielectric electrophoresis separation technology to realize the rapid and high-throughput continuous separation of particles.In this paper, the inertial focusing principle and the separation principle of dielectric electrophoresis particles are studied.The influence factors of particle focusing and the size of dielectric electrophoresis were analyzed according to the stress of particles in the channel.The frequency response characteristics of polystyrene pellets, yeast cells and NB4 cells were analyzed.Secondly, the structure of the chip is designed according to the principle of particle focusing and separation.The trapezoidal structure on the side wall of the entrance of the channel causes the particles passing through to be focused by inertial lift, and a set of tilted cross finger electrodes at the bottom of the channel generate a non-uniform electric field.By using the combination of electrophoretic force and fluid drag force, different particles are deflected into different channels at different angles, and the separation is realized.The internal electric field of the chip is simulated by Comsol Multiphysis software, and the height of the microchannel and the width and spacing of the interDigital electrode are optimized and determined.Thirdly, the microfluidic chip is fabricated. According to the function of the chip, the appropriate materials are selected, the microelectrode is fabricated on the surface of ITO glass by photolithography, the microchannel with focusing structure is fabricated by PDMS, and the chip is bonded by oxygen plasma.Make the chips needed for the experiment.Finally, the experiment platform was set up and the particle separation experiments were carried out. Firstly, the critical frequency of polystyrene pellets and yeast cells was measured by microtip electrode, and the separation frequency was determined and separated intermittently.Continuous separation of polystyrene pellets and yeast cells was carried out by using the designed electrode. The effects of flow rate and voltage on the separation were analyzed and the separation conditions were optimized to realize the continuous separation of polystyrene pellets and yeast cells.The separation efficiency and purity of yeast cell line Nb4 and polystyrene pellet Nb4 cells were analyzed statistically.
【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN492

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