【摘要】：連續(xù)性介電泳顆粒分離是微流控系統(tǒng)中對微納米樣品進行精確操控的核心手段,因為它在癌癥的早期診斷,水質(zhì)的污染分析等方面都有重要的應(yīng)用。通常情況下,連續(xù)性介電泳顆粒分離的過程需要將樣本聚集為寬度很小的粒子流以保證顆粒沿著相同軌跡運動并從相同的位置進入介電泳力作用范圍。然而,目前實現(xiàn)樣本顆粒聚集的方法只有流體擠壓效應(yīng),并且這種效應(yīng)需要冗余的外接設(shè)備,價格昂貴的微泵,復(fù)雜的多相流體操控。這使得微流芯片的高度集成化成了一個重大的挑戰(zhàn)。誘導(dǎo)電荷電滲聚集是發(fā)生在物體表面的一種電化學效應(yīng),已經(jīng)被證明是一種有效的顆粒聚集方法。因此,本文基于誘導(dǎo)電荷電滲流體聚集和介電泳偏移提出了一種新的顆粒分離方法。首先,分析了顆粒分離方法中的物理機理:基于對導(dǎo)體表面在交流電場中雙電層的形成機理的分析,推導(dǎo)了復(fù)振幅形式的誘導(dǎo)電荷電滲滑移速度公式;基于介電顆粒在非均勻電場中的偏極化效應(yīng),推導(dǎo)了顆粒在交流電場中受到介電泳力的形式;考慮電場,流場,重力場等因素的影響,分析了介電顆粒的受力情況并推導(dǎo)了顆粒在微流控芯片中的速度方程和軌跡方程。其次,對微流控芯片的關(guān)鍵位置進行初步設(shè)計并確定了合適的工作參數(shù):根據(jù)設(shè)計要求,對聚集區(qū)域,過渡區(qū)域,分離區(qū)域進行了初步設(shè)計;通過數(shù)值仿真研究確定了聚集區(qū)域的通道高度和工作參數(shù);基于拉格朗日顆粒軌跡追蹤的方法研究了過渡區(qū)域的結(jié)構(gòu)對粒子流狀態(tài)的影響規(guī)律;耦合電場,流場,重力場,通過數(shù)值仿真確定了適合顆粒分離的通道尺寸,分析了粒子流入口位置對顆粒分離效果的影響。再次,完成了微流控芯片的整體結(jié)構(gòu)設(shè)計與加工及實驗平臺的搭建:從改善整體性能和加工的角度出發(fā),進行了微流控芯片的整體結(jié)構(gòu)設(shè)計;運用標準軟光刻等技術(shù)完成了微流控芯片的加工;連接實驗器材,完成了實驗平臺的搭建。最后,在微流控芯片中進行了系統(tǒng)實驗:進行了顆粒誘導(dǎo)電荷電滲聚集特性和介電泳偏移特性研究;通過綜合實驗研究了入口流速對顆粒分離效果的影響,并對最佳狀態(tài)下顆粒分離效率進行了評估。
[Abstract]:Continuous meso-electrophoresis particle separation is the core method for accurate manipulation of microfluidic system, because it has important applications in the early diagnosis of cancer and the analysis of water pollution. In general, the process of separation of continuous meso-electrophoretic particles requires that the samples be clustered into a very small particle flow in order to ensure that the particles move along the same trajectory and move from the same position to the range of action of the medium electrophoretic force. However, the only way to achieve particle aggregation is the squeeze effect, which requires redundant external devices, expensive micropumps, and complex multiphase fluid manipulation. This makes the high degree of integration of microfluidic chips into a major challenge. Electroosmotic aggregation induced by charge is an electrochemical effect on the surface of an object, which has been proved to be an effective method for particle aggregation. Therefore, a new particle separation method is proposed based on the induced charge electroosmotic fluid aggregation and dielectric migration. Firstly, the physical mechanism of the particle separation method is analyzed. Based on the analysis of the formation mechanism of the double layer on the conductor surface in the alternating current field, the formula of the induced charge electroosmotic slip velocity in the form of complex amplitude is derived. Based on the polarization effect of dielectric particles in non-uniform electric field, the form of dielectric electrophoretic force in alternating current field is deduced, and the influence of electric field, flow field, gravity field and other factors are considered. The stress of dielectric particles is analyzed and the velocity equation and trajectory equation of particles in microfluidic chip are derived. Secondly, the key position of the microfluidic chip is preliminarily designed and the appropriate working parameters are determined: according to the design requirements, the initial design of the aggregation region, the transition region and the separation region is carried out; The channel height and working parameters of the agglomeration region are determined by numerical simulation. The influence of the structure of the transition region on the particle flow state is studied based on the Lagrangian particle trajectory tracing method; the coupling electric field, the flow field, the gravity field, the coupled electric field, the flow field, the gravity field, The size of the channel suitable for particle separation was determined by numerical simulation, and the influence of the inlet position of particle flow on the particle separation effect was analyzed. Thirdly, the whole structure design and machining of microfluidic chip and the construction of experimental platform are completed. From the point of view of improving the overall performance and machining, the whole structure design of microfluidic chip is carried out. The fabrication of microfluidic chip is accomplished by using standard soft lithography technology, and the experimental platform is built by connecting the experimental equipment. Finally, systematic experiments were carried out in microfluidic chip. The characteristics of particle induced charge electroosmotic aggregation and dielectric electrophoresis migration were studied, and the effect of inlet velocity on particle separation was studied. The particle separation efficiency was evaluated at the best condition.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O658.9

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本文編號：2186698