微流控芯片上的颗粒被动聚焦技术

Passive Focusing Techniques of Particles in Microfluidic Device

微流控芯片上的颗粒聚焦技术已广泛用于生物、化学、工程和医疗等领域。精确的聚焦过程是计数、检测或分选等应用的关键预处理步骤。颗粒聚焦技术根据是否引入外部能场和鞘流,分为主动聚焦、被动聚焦和鞘流辅助聚焦。被动聚焦利用流体的惯性、黏弹性等特性操控颗粒在流体中的平衡位置,拥有结构简单、高通量、生物兼容、低成本和无标记等多重优点。已有大量文献针对微流控芯片上的颗粒被动聚焦技术,从芯片的结构拓展、微流体特性和微粒特性等方面,开展了实验和数值计算研究。本文对微流控芯片上的颗粒被动聚焦技术最新研究进展进行了综述,首先对流体中颗粒受到的水动力和聚焦相关原则进行阐述,进一步详细综述被动聚焦技术进展,最后对该技术的未来发展作出了展望。

Particle focusing in microfluidic device is a rapidly growing research field due to its wide applications in biology,chemistry,engineering,and medicine.Precise and high-throughput focusing can be a pivotal pretreatment step for counting,detection and separation application.Generally,focusing technologies can be divided into active,passive and sheath-assisted methods.The active and sheath-assisted methods rely on external energy field or sheath flow,which can accurately control the position of particles in microchannel,but require integrating other complex functional elements.Passive focusing uses fluid inertia,viscoelasticity,and other characteristics to control the equilibrium position of particles in the microchannel,and it has been proven to be a powerful tool due to the simplicity,label-free,biocompatible,contact-free,low-cost,and high throughout nature.A large amount of experimental and numerical work has been carried out on the passive focusing technology from the aspects of chip structure,microfluidic characteristics,and particle characteristics.In this review,the fundamental hydrodynamic forces and the basic principles related to the focusing mechanism were firstly briefly introduced and discussed.Then the state of the art of detailed passive focusing methods was presented.At last,the focusing methods were summarized and future development in this field was predicted.