Efficient generation of droplets through three-dimensional fractal integrated coaxial flow channels

doi:10.11949/0438-1157.20240652

Abstract

Abstract:

Monodisperse droplets are widely used in food, chemical, energy, medicine and materials, but the current methods and devices are difficult to balance high monodispersity and high efficiency preparation. Therefore, a three-dimensional fractal approach is proposed to achieve equal and high-density integration of coaxial flow microchannels. And experimental research is conducted on the droplet generation characteristics and size distribution patterns. The experimental results show that under the condition of the stable mode, the coefficient of variation (CV) of droplets prepared by single channel, single stage 4-channel, and single stage 8-channel are 1.5%, 1.9%, and 1.9%, respectively. The monodispersity of droplets is high. Under the condition of the transition mode, the monodispersity of droplets is relatively poor, with CV of 6.9%, 6.7%, and 6.6%, respectively. Regardless of the stable mode or the transition interval of droplet generations, both the 4-channel and 8-channel channels maintain the characteristics of single channel droplet generation, and the generation efficiency is increased to nearly 4 and 8 times that of single channel, respectively. The droplets prepared with double-stage 16 channels at 4 flow rates exhibit good monodispersity, with CV all within 3.5%. But the generation efficiency has increased to nearly 16 times that of a single channel. The three-dimensional fractal integrated coaxial flow channel structure proposed in this article can improve the preparation efficiency while maintaining the monodispersity of droplets in single channel preparation.

Key words: droplet generation, microfluidics, integration, fractal, high throughput preparation, multiphase flow

摘要：

单分散性液滴在食品、化工、能源、医药和材料等领域均有广泛的应用，而现行方法及装置难以兼顾高单分散性和高效率制备。为此，提出了三维分形流道集成方法实现共轴流通道对等高密度集成，并采用简易方法构建了单级和双级三维分形共轴流通道集成装置；在此基础上实验研究其液滴生成特性及尺寸分布规律。无论稳定模式还是过渡模式的液滴生成，单级4通道与8通道均保持了单通道生成的液滴特性，而生成效率分别提高至单通道的近4倍与8倍。双级16通道在4组流量下制备的液滴单分散性好，变异系数均在3.5%以内；但生成效率提高到单通道的近16倍。可见三维分形集成共轴流通道结构能够在保持制备液滴单分散性的同时提升制备效率。

关键词: 液滴生成, 微流控, 集成, 分形, 高通量制备, 多相流

CLC Number:

TQ 050

Zhanzhu CHEN, Jinhua YE, Zhibin WANG, Zhi YANG, Lisi JIA, Ying CHEN. Efficient generation of droplets through three-dimensional fractal integrated coaxial flow channels[J]. CIESC Journal, 2024, 75(12): 4442-4452.

陈展珠, 叶锦华, 王智彬, 杨智, 贾莉斯, 陈颖. 三维分形集成共轴流通道实现液滴高效生成[J]. 化工学报, 2024, 75(12): 4442-4452.

Figures/Tables 10

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流体	密度/(kg/m³)	黏度/(Pa·s)	界面张力/(mN/m)
2%PVA溶液	1013.683	0.001498	5.08
97%HDDA溶液	1027.73	0.004482	5.08	1.54
0.7%洗涤剂溶液	1010.16	0.000579		1.54

流体	密度/(kg/m³)	黏度/(Pa·s)	界面张力/(mN/m)
2%PVA溶液	1013.683	0.001498	5.08
97%HDDA溶液	1027.73	0.004482	5.08	1.54
0.7%洗涤剂溶液	1010.16	0.000579		1.54

通道数	平均粒径/µm	生成效率/(个/min)	变异系数/%
单通道	1052	326	1.5
单级4通道	1054	1301	1.9
单级8通道	1055	2598	1.9

通道数	平均粒径/µm	生成效率/(个/min)	变异系数/%
单通道	1052	326	1.5
单级4通道	1054	1301	1.9
单级8通道	1055	2598	1.9

通道数	平均粒径/µm	生成效率/(个/min)	变异系数/%
单通道	956	873	6.9
单级4通道	957	3475	6.7
单级8通道	958	6944	6.6