Wang Junchao, Rodgers Victor G J, Brisk Philip, Grover William H
Department of Bioengineering, University of California, Riverside, California 92521, USA.
Department of Computer Science and Engineering, University of California, Riverside, California 92521, USA.
Biomicrofluidics. 2017 Jun 26;11(3):034121. doi: 10.1063/1.4989860. eCollection 2017 May.
Computer simulation plays a growing role in the design of microfluidic chips. However, the particle tracers in some existing commercial computational fluid dynamics software are not well suited for accurately simulating the trajectories of particles such as cells, microbeads, and droplets in microfluidic systems. To address this issue, we present a microfluidics-optimized particle simulation algorithm (MOPSA) that simulates the trajectories of cells, droplets, and other particles in microfluidic chips with more lifelike results than particle tracers in existing commercial software. When calculating the velocity of a particle, MOPSA treats the particle as a two-dimensional rigid circular object instead of a single point. MOPSA also checks for unrealistic interactions between particles and channel walls and applies an empirical correcting function to eliminate these errors. To validate the performance of MOPSA, we used it to simulate a variety of important features of microfluidic devices like channel intersections and deterministic lateral displacement (DLD) particle sorter chips. MOPSA successfully predicted that different particle sizes will have different trajectories in six published DLD experiments from three research groups; these DLD chips were used to sort a variety of different cells, particles, and droplets. While some of these particles are not actually rigid or spherical, MOPSA's approximation of these particles as rigid spheres nonetheless resulted in lifelike simulations of the behaviors of these particles (at least for the particle sizes and types shown here). In contrast, existing commercial software failed to replicate these experiments. Finally, to demonstrate that MOPSA can be extended to simulate other properties of particles, we added support for simulating particle density to MOPSA and then used MOPSA to simulate the operation of a microfluidic chip capable of sorting cells by their density. By enabling researchers to accurately simulate the behavior of some types of particles in microfluidic chips before fabricating the chips, MOPSA should accelerate the development of new microfluidic devices for important applications.
计算机模拟在微流控芯片设计中发挥着越来越重要的作用。然而，一些现有商业计算流体动力学软件中的粒子示踪器并不适合精确模拟微流控系统中细胞、微珠和液滴等粒子的轨迹。为了解决这个问题，我们提出了一种微流控优化粒子模拟算法（MOPSA），它能以比现有商业软件中的粒子示踪器更逼真的结果来模拟微流控芯片中细胞、液滴和其他粒子的轨迹。在计算粒子速度时，MOPSA将粒子视为二维刚性圆形物体而非单个点。MOPSA还会检查粒子与通道壁之间不切实际的相互作用，并应用经验校正函数来消除这些误差。为了验证MOPSA的性能，我们用它来模拟微流控设备的各种重要特征，如通道交叉点和确定性侧向位移（DLD）粒子分选芯片。MOPSA成功预测了在来自三个研究小组的六个已发表的DLD实验中，不同粒径的粒子会有不同的轨迹；这些DLD芯片用于分选各种不同的细胞、粒子和液滴。虽然其中一些粒子实际上并非刚性或球形，但MOPSA将这些粒子近似为刚性球体，仍然对这些粒子的行为进行了逼真的模拟（至少对于此处所示的粒径和类型的粒子）。相比之下，现有商业软件未能复制这些实验。最后，为了证明MOPSA可以扩展到模拟粒子的其他属性，我们为MOPSA添加了模拟粒子密度的支持，然后用MOPSA来模拟一个能够根据细胞密度分选细胞的微流控芯片的运行。通过使研究人员能够在制造芯片之前准确模拟微流控芯片中某些类型粒子的行为，MOPSA应该会加速用于重要应用的新型微流控设备的开发。
