Department of Mechanical Engineering, Sharif University of Technology, Azadi St., Tehran 11155, Iran.
Department of Mechanical Engineering, University of Waterloo, 200 University Avenue West, N2L 3G, Waterloo, ON N2L 3G1, Canada.
Sensors (Basel). 2020 Jul 5;20(13):3774. doi: 10.3390/s20133774.
Droplet-based microfluidics offers significant advantages, such as high throughput and scalability, making platforms based on this technology ideal candidates for point-of-care (POC) testing and clinical diagnosis. However, the efficiency of co-encapsulation in droplets is suboptimal, limiting the applicability of such platforms for the biosensing applications. The homogeneity of the bioanalytes in the droplets is an unsolved problem. While there is extensive literature on the experimental setups and active methods used to increase the efficiency of such platforms, passive techniques have received less attention, and their fundamentals have not been fully explored. Here, we develop a novel passive technique for investigating cell encapsulation using the finite element method (FEM). The level set method was used to track the interfaces of forming droplets. The effects of walls and the droplet interfaces on relatively large cells were calculated to track them more accurately during encapsulation. The static surface tension force was used to account for the effects of the interfaces on cells. The results revealed that the pairing efficiency is highly sensitive to the standard deviation (SD) of the distance between the cells in the entrance channel. The pairing efficiency prediction error of our model differed by less than 5% from previous experiments. The proposed model can be used to evaluate the performance of droplet-based microfluidic devices to ensure higher precision for co-encapsulation of cells.
基于液滴的微流控技术具有高通量和可扩展性等显著优势，使其成为即时检测（POC）和临床诊断的理想候选平台。然而，液滴内的共包封效率并不理想，限制了此类平台在生物传感应用中的适用性。液滴中生物分析物的均一性是一个尚未解决的问题。虽然有大量关于用于提高此类平台效率的实验装置和主动方法的文献，但被动技术受到的关注较少，其基本原理尚未得到充分探索。在这里，我们使用有限元法（FEM）开发了一种用于研究细胞包封的新型被动技术。使用水平集方法来跟踪形成液滴的界面。计算了壁和液滴界面对相对较大细胞的影响，以便在包封过程中更准确地跟踪它们。静态表面张力用于说明界面对细胞的影响。结果表明，配对效率对入口通道中细胞之间距离的标准偏差（SD）非常敏感。我们模型的配对效率预测误差与以前的实验相差不到 5%。所提出的模型可用于评估基于液滴的微流控设备的性能，以确保细胞共包封的更高精度。
