Institute State Key Laboratory for Manufacturing Systems Engineering, School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an, 710054, China.
School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore.
Lab Chip. 2023 Nov 21;23(23):5039-5046. doi: 10.1039/d3lc00434a.
Flow cytometry is an essential technique in single particle analysis and cell sorting for further downstream diagnosis, exhibiting high-throughput and multiplexing capabilities for many biological and biomedical applications. Although many hydrodynamic focusing-based microfluidic cytometers have been demonstrated with reduced size and cost to adapt to point-of-care settings, the operating conditions are not characterized systematically. This study presents the flow transition process in the hydrodynamic focusing mechanism when the flow rate or the Reynolds number increases. The characteristics of flow fields and mass transport were studied under various operating conditions, including flow rates and microchannel heights. A transition from the squeezed focusing state to the over-squeezed anti-focusing state in the hydrodynamic focusing regime was observed when the Reynolds number increased above 30. Parametric studies illustrated that the focusing width increased with the Reynolds number but decreased with the microchannel height in the over-squeezed state. The microfluidic cytometric analyses using microbeads and show that the recovery rate was maintained by limiting the Reynolds number to 30. The detailed analysis of the flow transition will provide new insight into microfluidic cytometric analyses with a broad range of applications in food safety, water monitoring and healthcare sectors.
流式细胞术是单颗粒分析和细胞分选的一项重要技术，可用于进一步的下游诊断，在许多生物和生物医学应用中具有高通量和多重检测能力。尽管已经有许多基于流体动力聚焦的微流控细胞仪具有更小的尺寸和更低的成本，以适应即时检测的环境，但操作条件并没有得到系统的描述。本研究介绍了在流速或雷诺数增加时，流体动力聚焦机制中的流过渡过程。在各种操作条件下，包括流速和微通道高度，研究了流场和质量传递的特性。当雷诺数增加到 30 以上时，观察到在流体动力聚焦区从挤压聚焦状态到过挤压反聚焦状态的转变。参数研究表明，在过挤压状态下，聚焦宽度随雷诺数的增加而增加，但随微通道高度的增加而减小。使用微珠和 的微流控细胞分析表明，通过将雷诺数限制在 30 以内，可以保持较高的回收率。对流动过渡的详细分析将为微流控细胞分析提供新的见解，该分析在食品安全、水质监测和医疗保健等领域具有广泛的应用。
