【作者】 徐文超；

【导师】 吴志刚；

【作者基本信息】 华中科技大学 ， 机械电子工程， 2017， 硕士

【摘要】 近二十来年,微流控因其高效率、高准确度以及低成本的优势在生物和医疗应用中受到极大关注。随着临床医疗对高效率和低消耗的需求日趋迫切。同时从混合颗粒溶液中分离出特定的目标颗粒一直是微流控应用中经典的研究领域之一。所以通过微流控芯片来研究细胞分离实验符合临床医疗对效率和成本的要求,具有重大临床意义。本文利用微流控芯片作为平台,提出了一种基于水动力作用进行细胞分离的新方法。在该方法中,通过在样本流两侧引入粘度不同的鞘流,使得样本流被非对称聚焦。同时样本流被加速且呈现具有高速度梯度的流速分布。作用于颗粒上的水动力即Saffman升力因颗粒处于高速度梯度的流场中,对颗粒的偏移起到关键性影响。大颗粒将偏移原来的流线向相对速度大的一侧运动。而小细胞始终保持在原来的流线上或相对大颗粒其偏移较小,通过偏移量的不同,从而实现不同尺寸细胞的分离。为了获得更加准确的实验结果,在本文实验中用1.0μm(红色荧光)和9.9μm(绿色荧光)聚苯乙烯颗粒进行了原理验证和变量的量化分析实验。最后一章用血细胞和大肠杆菌作为分离样本证明该方法在实际生物应用上的可行性。通过一系列验证实验,证明了本文提出的有关新分离方法的原理分析。而后通过对变量量化实验,发现分离效果随着低粘度鞘流的流量、高低粘度鞘流粘度差异增大而更好,而随着通道整体流量同比增大和高粘度鞘流的流量增大而变差。最后利用本文提出的新分离方法成功实现了大小颗粒的分选富集,以及血细胞和大肠杆菌的分离验证。更多还原

【Abstract】 Microfluidics has been attracting significant attention for the past two decades due to its high efficiency,accuracy and low cost in biological and medical applications.Needs of high efficiency and low consumption in the clinical care are increasingly urgent.Meanwhile,separating target particles from the mixture is one of the classical research fields in these microfluidic applications.So separating desired cells by using microfluidic chips meets requirements of medical treatment about efficiency and cost,which has a great clinical significance.This thesis presents a new approach for cell separation based on hydrodynamic force by using microfluidic chips as a platform.The asymmetric focusing of sample flow is formed by the induced sheath flows with different viscosity on the sides of sample flow.Meanwhile,the accelerated motion and the velocity profile of high-velocity gradient in the sample flow is obtained.The hydrodynamic force(Saffman lift force)induced by the highvelocity gradient is exerted on particles,which plays a dominate role in the particle deflection due to the high-velocity gradient.The larger particles will deflect away from their original streamline to the high relative velocity side,while the smaller particles remain close to their streamline or experience a smaller deflection than the larger particles.Through different deflection,the different size particles can be separated.In order to obtain accurate experimental result,two kinds of polystyrene microspheres with diameters 1.0 μm(red fluorescent)and 9.9 μm(green fluorescent)are adopted as the sample to verify the principle and quantify the difference of variables in experiments of this thesis.In final chapter,blood cells and Escherichia coli are used as the sample to verify the feasibility of this new approach in the biological application.Through a series of validation experiments,the analysis about the principle of this new particle separation approach is verified.The results of quantitative experiments indicated increasing of the flow rate of low-viscosity sheath flow and viscosity difference between high-viscosity and low-viscosity sheath flows improves separation effect.While increasing of keeping flow rate ratio among sample flow and sheath flows and flow rate of highviscosity sheath flow weaken separation effect.At last,separation and enrichment of different size particles and separation between blood cells and Escherichia coli are successfully achieved by using this new approach.更多还原