基于晶格Boltzmann方法研究亚微米颗粒可调控的惯性聚集和分选

微流控技术的蓬勃发展为颗粒跨流层惯性聚集现象开辟了应用舞台；不依赖外部力场而仅凭借流体力学机制，惯性微流控能够在传统微流控技术不再适用的高速度下控制微颗粒的汇聚和分离。然而，目前惯性微流控还不能有效地操控亚微米尺度的颗粒，也不能实时地调整颗粒在通道内的聚集位置；为提高颗粒聚集速度而采用的曲线型通道，既增加了系统的复杂性，又阻碍了利用大量通道并行来提高微流控芯片的吞吐量。本项目拟耦合热涨落和边界滑移发展介观的晶格Boltzmann方法，对典型亚微米生物颗粒的惯性微流控进行系统的模拟研究，探索亚微米尺度颗粒惯性聚集和分选的特有规律。在直型通道内，采用电润湿的边界调控机制控制流速分布和局部二次流，加速颗粒汇聚和实时调控颗粒的聚集位置。这些研究有助于深入理解惯性微流控中各种非线性因素的作用，实现灵活地操控亚微米生物颗粒，并基于直通道并行结构设计高吞吐量的微流控芯片。

With the rapid development of microfluidics, inertial focusing and separation have gained significant attention. Independently of the external force field, inertial microfluidics offers accurate control of microparticles by means of purely hydrodynamic interactions at high speeds at which traditional microfluidic can no longer work. However, inertial microfluidics cannot effectively control submicron- and nano-scale bioparticle, nor can real-time regulate the position of particle focusing in the microchannel. The curved and spiral channels, which are often used to improve the focusing efficiency, increase the system complexity and hinder improving the throughput by parallel structure. In this project, a lattice Boltzmann model coupled with thermal fluctuation and boundary slip will be developed to numerically study the inertial microfluidics of submicron bioparticles and deeply investigate the characteristic laws of submicron inertial focusing and separation. The electrowetting and boundary slip are utilized to regulate the fluid velocity distribution and the local secondary flow in the straight channel. This not only promotes the focusing efficiency but also actively control the focusing position. These studies will be helpful to understand the interactions of the nonlinear factors in inertial microfluidics, realize more accurate and flexible control of the submicron bioparticles, and design high-throughput microfluidic chips based on the parallel of straight channels.