液滴调控的诱导电荷电渗颗粒高效浓缩及定向收集研究

发布时间：2018-05-22 08:42

  本文选题：诱导电荷电渗 + 液滴调控　； 参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：基于微流控技术的生化反应或药物诊断过程中,使细菌或生物细胞等微小颗粒快速富集,并将样本体积缩减到微流控器件能够操控的有效范围是分析过程的最基本环节。常规的颗粒收集方法如介电泳、交流电渗、诱导电荷电渗等大多存在诸如收集效率低等问题,因此,本文提出了一种基于液滴调控的诱导电荷电渗颗粒高效浓缩及定向收集方法,利用液滴在直通道中构建可以灵活调控的收缩区,并通过收缩区形成的特殊尾流模式提高颗粒的收集效率,最后通过液滴的调控实现粒子束的定向收集。首先,分析了诱导电荷电渗颗粒聚集的机理:基于经典的RC电路理论推导了正弦稳态信号下悬浮电极表面的电渗滑移流速;通过对微通道内流场的数值求解得到了空间流场的分布特性,阐明了悬浮电极上方反向漩涡形成的流动停滞线与颗粒聚集现象的关系并研究了诱导电荷电渗的电控特性。其次,揭示了收缩区影响颗粒收集现象的机理:提出了空间中颗粒运动轨迹的物理描述,分析了颗粒在收缩区上游的流动诱导电荷电渗聚焦过程;阐明了对称液滴构成的收缩区尾部特殊的发散-汇聚模式的机理,解释了上游泄漏到通道两侧的颗粒被重新收集的原因;分析了非对称液滴对流场的影响,归纳了液滴调控粒子束定向收集的规律。再次,设计制作了微芯片并分析了实验参数的影响:根据诱导电渗流的几何特性,基于实验器件的关键尺寸设计了液滴调控的颗粒高效浓缩芯片和集成芯片;研究了电导率、入口流速和液滴曲率半径等关键实验参数对颗粒收集的影响,优选了实验参数取值;确定了芯片的加工工艺并进行了实验准备和实验平台的搭建。最后,进行了颗粒高效浓缩实验和粒子束定向收集实验:颗粒高效浓缩实验确认了收缩区结构的实时可调控性和用于提高颗粒收集效率的可行性,实验效果与理论模型相符;粒子束定向收集实验体现了集成芯片对颗粒的多种操控模式,证明了非对称液滴对粒子束的定向收集具有准确有效的调控作用,实验结果验证了本文所提方案在实现颗粒高效浓缩和定向收集方面的有效性。
[Abstract]:In the process of biochemical reaction or drug diagnosis based on microfluidic technology the microparticles such as bacteria or biological cells are rapidly enriched and the sample volume is reduced to the effective range that the microfluidic device can control. Conventional particle collection methods, such as dielectric electrophoresis, alternating current electroosmosis, induced charge electroosmosis, and so on, have problems such as low collection efficiency. In this paper, a method of high efficiency concentration and directional collection of induced charge electroosmotic particles based on droplet control is proposed. The particle collection efficiency is improved by the special wake mode formed in the constriction region, and the directional collection of the particle beam is realized through the droplet regulation. Firstly, the mechanism of induced charge electroosmotic particle aggregation is analyzed. Based on the classical RC circuit theory, the electroosmotic slip velocity on the surface of the suspended electrode is derived under the sinusoidal steady state signal. Through the numerical solution of the flow field in the microchannel, the distribution characteristics of the spatial flow field are obtained, the relationship between the flow stagnation line formed by the reverse vortex over the suspension electrode and the phenomenon of particle aggregation is clarified, and the electrically controlled characteristics of the induced charge electroosmosis are studied. Secondly, the mechanism of particle collection in shrinkage region is revealed. The physical description of particle trajectory in space is presented, and the flow induced charge electroosmotic focusing process of particles upstream in the shrinkage region is analyzed. The mechanism of the special divergence-convergence model in the tail of the contraction region of symmetrical droplets is explained, the reason for the recollection of particles from upstream to both sides of the channel is explained, and the effect of asymmetric droplets on the flow field is analyzed. The rule of directional collection of droplet controlled particle beam is summarized. Thirdly, the microchip is designed and fabricated and the influence of experimental parameters is analyzed. According to the geometric characteristics of induced electroosmotic flow, the droplet controlled particle high efficiency concentration chip and integrated chip are designed based on the key dimensions of the experimental device, and the conductivity of the chip is studied. The influence of the key experimental parameters such as inlet velocity and the radius of curvature of the droplet on the particle collection is optimized. The processing technology of the chip is determined and the experimental preparation and experimental platform are built. Finally, the experiments of particle high efficiency concentration and particle beam directional collection were carried out. The experiment confirmed the real time controllability of the constriction region structure and the feasibility of using it to improve the particle collection efficiency. The experimental results were consistent with the theoretical model. The experiments of particle beam directional collection show that the integrated chip controls the particles in a variety of modes, which proves that the directional collection of asymmetric droplets to particle beams has an accurate and effective control effect. The experimental results verify the effectiveness of the proposed scheme in achieving high efficiency particle concentration and directional collection.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O652.9
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本文编号：1921382