用于流式细胞仪的超声聚焦系统的仿真与设计

Simulation and design of an acoustic focusing system for flow cytometer

介绍了一种利用超声驻波对颗粒进行二维聚焦的方案,其可用于流式细胞仪中微量(少于82μL)细胞样品的上样,无需鞘液即可实现颗粒在管道中央的逐个排列,并能以高至0.5 m L/min的速度依次通过检测区。该方案避免了颗粒在管道中的随机分布现象,提高了流式细胞检测的准确性,分析后的样品还能被无稀释地回收再利用。从驻波形成、声阻抗匹配、颗粒在声场中的受力分析等理论出发,着重仿真分析了驻波场中颗粒在不同参数下的运动路径。在理论模型的基础上搭建了1.462 MHz频率驱动的方形毛细管实验平台,利用10和20μm直径的聚苯乙烯微球验证了超声聚焦颗粒的可行性,实验表明低流速、高声场强度时聚焦更紧密,大颗粒比小颗粒更易聚焦。该结论与仿真结果一致。

This work demonstrates a standing wave focusing method to complete two-dimension and sheath-free focusing of particles for flow cytometer. Cells or beads in a volume of less than 82 μL are forced to cross the detection area one by one under a flow rate higher than 0.5 mL/min, which can improve the analysis accuracy and realize undiluted sample recovery. The principle of standing wave formation, acoustic resistance matching and the particle force equilibrium are discussed, and the motion trajectory of particle under different parameters is simulated. Referring to this model, an acoustic focusing experimental platform driving in a frequency of 1. 462 MHz is built to verify the feasibility and performance by polystyrene beads in diameters of 10 and 20 μm. The results showed that beads in random distribution can be focused into a plane, and more tightly focusing can be achieved at low flow rate and high driving voltage. It is proved that the bigger beads are focused more easily than the smaller ones. All the experimental results coincides well with the simulation.