基于显微图像识别的微流控液滴聚并研究

doi:10.11949/0438-1157.20190738

摘要/Abstract

摘要：

微流控技术作为操控微米尺度液滴的重要手段，受到普遍关注。显微摄像是微流控过程的主要研究方法，以往主要通过人工观察识别的方式获取关键参数，工作效率低、数据量小，限制了针对复杂微流控过程的深入认识。提出了一种基于MATLAB图像处理程序的微流控液滴聚并研究方法，通过背景提取、背景扣除、掩膜二值化、噪声消除、区域填充、形态开启、边界物体移除、干扰滤除等过程，实现六边形扩大通道内液滴聚并显微实验视频的数值化，进一步通过识别液滴投影面积、质心、偏心率等信息，研究了液滴运动速度和液膜的排空时间等微流控聚并关键参数的变化规律。

关键词: 微流控, 聚并, 显微分析, 图像识别

Abstract:

Microfluidic technology, as an important approach of manipulating micrometer-scale droplets, has received widespread attention. Microscope recording is the main research method of micro-fluidic process. In the past, key parameters were mainly obtained through manual observation and identification. The low efficiency and small amount of data limited the in-depth understanding of complex micro-fluidic processes. This paper proposes a method to studying microfluidic droplet coalescence based on MATLAB image processing program with background extraction, background subtraction, mask binarization, noise elimination, region filling, shape opening, boundary object removal, interference filtering and etc., which digitized the microscopic videos experimentally collected in a hexagonal microchannel. Furthermore, by identifying the droplet projection area, centroid, eccentricity and other information, the key parameters of microfluidic processes, including droplet speed and liquid film drainage time are also studied.

Key words: microfluidics, coalescence, microscope image analysis, video recognition

中图分类号:

TQ 025.5

张皓, 王凯. 基于显微图像识别的微流控液滴聚并研究[J]. 化工学报, 2020, 71(2): 526-534.

Hao ZHANG, Kai WANG. Microfluidic droplet coalescence study via microscopic image recognition[J]. CIESC Journal, 2020, 71(2): 526-534.

图/表 9

图1 微通道实验装置

Fig. 1 Schematic diagram of microchannel equipment

表1 实验体系物性 (27°C)

Table 1 Physical properties of working systems

实验体系	黏度/(mPa·s)	密度/(g·cm^-3)	界面张力/(mN·m^-1)
正辛醇	7.03	0.819	7.55
0.05% SiO₂溶液	7.18	0.821	7.61
0.10% SiO₂溶液	7.22	0.833	7.58

图2 液滴聚并与不接触现象

Fig.2 Phenomena of droplet coalescence and out of touch

图3 背景图像获取过程

Fig.3 Background image acquisition process

图4 显微图像的数字化过程

Fig.4 Digitization process of microscopic images

图5 干扰滤除过程

Fig.5 Interference filtering processes

图6 微液滴状态判据说明

Fig.6 Explanation of microdroplet states

图7 液滴运动速度分析

Fig.7 Analysis of droplet moving speed

表2 液膜排空时间分析结果

Table 2 Analysis results of liquid film drainage time

颗粒含量/%	流量Q_c1/ (μl·min^-1)	流量Q_d/ (μl·min^-1)	流量Q_c2/ (μl·min^-1)	液滴投影面积 S /mm²	液膜排空时间 t_d/s	液滴接触点位置 x /mm
0 0 0	10	3	0	0.20 ~ 0.22	0.121 ± 0.031	0.42 ~ 0.43
	10	4	0	0.20 ~ 0.22	0.120 ± 0.033	0.40 ~ 0.42
	10	5	0	0.23 ~ 0.25	0.132 ± 0.020	0.36 ~ 0.37
0.05 0.05	20	10	0	0.22 ~ 0.25	0.103 ± 0.041	0.42 ~ 0.43
0.05 0.05	20	10	1	0.22 ~ 0.25	0.130 ± 0.052	0.37 ~ 0.39
0.10 0.10	10	5	0	0.25 ~ 0.26	0.181 ± 0.076	0.47 ~ 0.48
0.10 0.10	20	10	0	0.23 ~ 0.24	0.177 ± 0.066	0.40 ~ 0.41

参考文献 30

1	Jensen K F. Flow chemistry—microreaction technology comes of age[J]. AIChE Journal, 2017, 63(3): 858-869.
2	Kockmann N. Modular equipment for chemical process development and small-scale production in multipurpose plants[J]. Chembioeng Reviews, 2016, 3(1): 5-15.
3	Rossetti I, Compagnoni M. Chemical reaction engineering, process design and scale-up issues at the frontier of synthesis: flow chemistry[J]. Chemical Engineering Journal, 2016, 296: 56-70.
4	Wang K, Luo G. Microflow extraction: a review of recent development[J]. Chemical Engineering Science, 2017, 169: 18-33.
5	Kjeang E, Djilali N, Sinton D. Microfluidic fuel cells: a review[J]. Journal of Power Sources, 2009, 186(2): 353-369.
6	Anna S L. Droplets and bubbles in microfluidic devices[J]. Annual Review of Fluid Mechanics, 2016, 48: 285-309.
7	Zhu P, Wang L. Passive and active droplet generation with microfluidics: a review[J]. Lab on a Chip, 2016, 17(1): 34-75.
8	Koster S. Microfluidics—from fundamental research to industrial applications[J]. Journal of Physics D: Applied Physics, 2013, 46: 110301.
9	Yamada K, Henares T G, Suzuki K, et al. Paper-based inkjet-printed microfluidic analytical devices[J]. Angewandte Chemie International Edition, 2015, 54(18): 5294-5310.
10	Shui L, Hayes R A, Jin M, et al. Microfluidics for electronic paper-like displays[J]. Lab on a Chip, 2014, 14(14): 2374-2384.
11	Waheed S, Cabot Canyelles J, Macdonald N, et al. 3D printed microfluidic devices: enablers and barriers[J]. Lab on a Chip, 2016, 16(11): 1993-2013.
12	Wang K, Li L, Xie P, et al. Liquid-liquid microflow reaction engineering[J]. Reaction Chemistry & Engineering, 2017, 2(5): 611-627.
13	Wang J, Song Y. Microfluidic synthesis of nanohybrids[J]. Small, 2017, 13: 160408418.
14	Kim H U, Choi D G, Roh Y H, et al. Microfluidic synthesis of pH-sensitive multicompartmental microparticles for multimodulated drug release[J]. Small, 2016, 12(25): 3463-3470.
15	Atobe M, Tateno H, Matsumura Y. Applications of flow microreactors in electrosynthetic processes[J]. Chemical Reviews, 2018, 118: 4541-4572
16	Yao C, Liu Y, Xu C, et al. Formation of liquid-liquid slug flow in a microfluidic T-junction: effects of fluid properties and leakage flow[J]. AIChE Journal, 2018, 64(1): 346-357.
17	Li Y K, Wang K, Xu J H, et al. A capillary-assembled micro-device for monodispersed small bubble and droplet generation[J]. Chemical Engineering Journal, 2016, 293: 182-188.
18	Li Z, Mak S Y, Sauret A, et al. Syringe-pump-induced fluctuation in all-aqueous microfluidic system implications for flow rate accuracy[J]. Lab on a Chip, 2014, 14(4): 744-749.
19	Saqib M, Sahinoglu O B, Erdem E Y. Alternating droplet formation by using tapered channel geometry[J]. Scientific Reports, 2018, 8: 1606.
20	Wu Z, Cao Z, Sundén B. Liquid-liquid flow patterns and slug hydrodynamics in square microchannels of cross-shaped junctions[J]. Chemical Engineering Science, 2017, 174: 56-66.
21	Galindo-Rosales F J, Alves M A, Oliveira M. Microdevices for extensional rheometry of low viscosity elastic liquids: a review[J]. Microfluidics and Nanofluidics, 2013, 14(1/2): 1-19.
22	Seemann R, Brinkmann M, Pfohl T, et al. Droplet based microfluidics[J]. Reports on Progress in Physics, 2012, 75: 0166011.
23	Wei W, Guo S, Wu F, et al. Image processing-based measurement of volume for droplets in the microfluidic system[C]// Complex Medical Engineering (CME), 2013 ICME International Conference on. IEEE, 2013: 518-522.
24	Basu A S. Droplet morphometry and velocimetry (DMV): a video processing software for time-resolved, label-free tracking of droplet parameters[J]. Lab on a Chip, 2013, 13(10): 1892-1901.
25	Xu K, Tostado C P, Xu J H, et al. Direct measurement of the differential pressure during drop formation in a co-flow microfluidic device[J]. Lab on a Chip, 2014, 14(7): 1357-1366.
26	Liu Z, Cao R, Pang Y, et al. The influence of channel intersection angle on droplets coalescence process[J]. Experiments in Fluids, 2015, 56(2): 24.
27	Wu Y, Fu T, Zhu C, et al. Bubble coalescence at a microfluidic T-junction convergence: from colliding to squeezing[J]. Microfluidics and Nanofluidics, 2014, 16(1/2): 275-286.
28	王凯, 易诗婷, 周倩倩, 等. 微通道内纳米颗粒对液滴聚并的影响规律[J]. 化工学报, 2016, 67(2): 469-475.
	Wang K, Yi S T, Zhou Q Q, et al. Effect of nano-particles on droplet coalescence in microchannel device[J]. CIESC Journal, 2016, 67(2): 469-475.
29	Wang K, Luo G S. Microflow extraction: a review of recent development[J]. Chemical Engineering Science, 2017, 169(SI): 18-33.
30	Zhou Q Q, Sun Y, Yi S T, et al. Investigation of droplet coalescence in nanoparticle suspensions by a microfluidic collision experiment[J]. Soft Matter, 2016, 12(6): 1674-1682.

[1]	张银宁, 王进卿, 冯致, 詹明秀, 徐旭, 张光学, 池作和. 升温条件下多孔介质内气泡的生长和聚并行为[J]. 化工学报, 2023, 74(4): 1509-1518.
[2]	邓璐, 巨晓洁, 张文杰, 谢锐, 汪伟, 刘壮, 潘大伟, 褚良银. 微流控法可控制备放射性壳聚糖栓塞微球[J]. 化工学报, 2023, 74(4): 1781-1794.
[3]	贾露凡, 王艺颖, 董钰漫, 李沁园, 谢鑫, 苑昊, 孟涛. 微流控双水相贴壁液滴流动强化酶促反应研究[J]. 化工学报, 2023, 74(3): 1239-1246.
[4]	黄心童, 耿宇昊, 刘恒源, 陈卓, 徐建鸿. 微流控制备新型功能纳米粒子研究进展[J]. 化工学报, 2023, 74(1): 355-364.
[5]	李承威, 骆华勇, 张铭轩, 廖鹏, 方茜, 荣宏伟, 王竞茵. 氢氧化镧交联壳聚糖微球的微流控制备及其除磷性能[J]. 化工学报, 2022, 73(9): 3929-3939.
[6]	万景, 张霖, 樊亚超, 刘勰民, 骆培成, 张锋, 张志炳. 基于介尺度PBM模型的生物反应器放大模拟及实验研究[J]. 化工学报, 2022, 73(6): 2698-2707.
[7]	潘大伟, 汪伟, 谢锐, 巨晓洁, 刘壮, 褚良银. 微流控乳液模板法构建功能微颗粒过程中介尺度结构定向调控的研究进展[J]. 化工学报, 2022, 73(6): 2306-2317.
[8]	杨蕊, 朱宝锦, 吕超, 张磊, 肖迎松. 脉动条件下旋流场内气液两相流流型及其转变机理[J]. 化工学报, 2022, 73(10): 4389-4398.
[9]	费滢洁, 朱春英, 付涛涛, 高习群, 马友光. Y型微通道内纳米颗粒稳定气泡的完全阻塞破裂动力学[J]. 化工学报, 2022, 73(1): 213-221.
[10]	赵峻逸, 薛士东, 韩敬坤, 温荣福, 兰忠, 郝婷婷, 马学虎. 双液滴碰撞行为及调控机制的研究进展[J]. 化工学报, 2021, 72(5): 2354-2372.
[11]	陈祯, 刘静, 朱春英, 付涛涛, 马友光. T型微通道内浆料体系中气泡生成行为与尺寸预测[J]. 化工学报, 2021, 72(2): 928-936.
[12]	张华海, 王悦琳, 王铁峰. 全浓度范围下醇类表面活性剂对气泡聚并影响的实验研究[J]. 化工学报, 2020, 71(9): 4161-4167.
[13]	刘子炜, 戴诗逸, 段聪, 张志伟, 庞子凡, 朱春英, 付涛涛, 马友光. 台阶式单微通道内气泡生成动力学[J]. 化工学报, 2020, 71(2): 552-565.
[14]	陈宇超, 崔永晋, 王凯, 骆广生. 阶梯式T型微通道内液滴、气泡分散规律[J]. 化工学报, 2020, 71(1): 265-273.
[15]	李阳, 杜乐, 高若梅, 吴偲, 龚亚辉. 微通道中原位分散技术可控制备氧化铜纳米流体及复合薄膜前体[J]. 化工学报, 2018, 69(11): 4918-4928.