Optical-based microfluidic cell sorting has become increasingly attractive for applications in life and environmental sciences due to its ability of sophisticated cell handling in flow. The majority of these microfluidic cell sorting devices employ two-dimensional fluid flow control strategies, which lack the ability to manipulate the position of cells arbitrarily for precise optical detection, therefore resulting in reduced sorting accuracy and purity. Although three-dimensional (3D) hydrodynamic devices have better flow-focusing characteristics, most lack the flexibility to arbitrarily position the sample flow in each direction. Thus, there have been very few studies using 3D hydrodynamic flow focusing for sorting. Herein, we designed a 3D hydrodynamic focusing sorting platform based on independent sheath flow-focusing and pressure-actuated switching. This design offers many advantages in terms of reliable acquisition of weak Raman signals due to the ability to precisely control the speed and position of samples in 3D. With a proof-of-concept demonstration, we show this 3D hydrodynamic focusing-based sorting device has the potential to reach a high degree of accuracy for Raman activated sorting.

由于基于光学的微流细胞分选技术能够在流动中进行复杂的细胞处理，因此在生命科学和环境科学领域的应用变得越来越有吸引力。这些微流体细胞分选设备中的大多数采用二维流体流控制策略，该策略缺乏为精确的光学检测而任意操纵细胞位置的能力，因此导致分选准确性和纯度降低。尽管三维（3D）流体动力装置具有更好的流动聚焦特性，但大多数装置都缺乏在每个方向上随意放置样品流的灵活性。因此，很少有研究使用3D流体动力流聚焦进行分类。在此处，我们设计了一个基于独立鞘流聚焦和压力驱动切换的3D流体动力聚焦分类平台。由于能够精确控制3D样本的速度和位置，因此该设计在可靠捕获弱拉曼信号方面具有许多优势。通过概念验证演示，我们展示了这种基于3D流体动力聚焦的分拣设备具有拉曼激活分拣具有很高准确性的潜力。