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Study of flow behaviors of droplet merging and splitting in microchannels using Micro-PIV measurement

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Abstract

Droplet merging and splitting are important droplet manipulations in droplet-based microfluidics. However, the fundamental flow behaviors of droplets were not systematically studied. Hence, we designed two different microstructures to achieve droplet merging and splitting respectively, and quantitatively compared different flow dynamics in different microstructures for droplet merging and splitting via micro-particle image velocimetry (micro-PIV) experiments. Some flow phenomena of droplets different from previous studies were observed during merging and splitting using a high-speed microscope. It was also found the obtained instantaneous velocity vector fields of droplets have significant influence on the droplets merging and splitting. For droplet merging, the probability of droplets coalescence (η) in a microgroove is higher (50% < η < 92%) than that in a T-junction microchannel (15% < η < 50%), and the highest coalescence efficiency (η = 92%) comes at the two-phase flow ratio e of 0.42 in the microgroove. Moreover, compared with a cylinder obstacle, Y-junction bifurcation can split droplets more effectively and the droplet flow during splitting is steadier. The results can provide better understanding of droplet behaviors and are useful for the design and applications of droplet-based microfluidics.

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Acknowledgements

This work was supported by the Beijing Municipal Natural Science Foundation (7152012), General Program of Science and Technology Development Project of Beijing Municipal Education Commission (KM201610005002), Natural Science Foundation of China (11572013), China Scholarship Council (201406545031), Training Plan of New Talent of Beijing University of Technology (2015-RX-L02), NIH (R21AI107415 and SC2GM105584), and the NSF-PREM program (DMR 1205302).

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Authors and Affiliations

  1. College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology, Beijing, 100124, China

    Feng Shen, Yi Li & Zhaomiao Liu

  2. Department of Chemistry, University of Texas at El Paso, El Paso, TX, 79968, USA

    XiuJun Li

  3. Border Biomedical Research Center, University of Texas at El Paso, El Paso, TX, 79968, USA

    XiuJun Li

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  1. Feng Shen
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  2. Yi Li
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Correspondence to Feng Shen or XiuJun Li.

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This article is part of the topical collection “2016 International Conference of Microfluidics, Nanofluidics and Lab-on-a-Chip, Dalian, China” guest edited by Chun Yang, Carolyn Ren and Xiangchun Xuan.

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Shen, F., Li, Y., Liu, Z. et al. Study of flow behaviors of droplet merging and splitting in microchannels using Micro-PIV measurement. Microfluid Nanofluid 21, 66 (2017). https://doi.org/10.1007/s10404-017-1902-y

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