Coalescences of microdroplets at a cross-shaped microchannel junction without strictly synchronism control

Wang, Kai; Lü, Yangcheng; Tostado, Chris P.; Lu, Yang; Luo, Guangsheng

doi:10.1016/j.cej.2012.09.060

Cited by 31 publications

(16 citation statements)

References 36 publications

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“…Usually, the microdroplets for merging should arrive at the T-shaped junction at the same time, and the contact time of microdroplets is very short. However, due to the two-phase flow characteristics in microchannel and other uncontrollable factors of microdroplets transportation, etc., the synchronism of microdroplets is hard to maintain in the actual operating process, especially for the head-on collision of microdroplets at a T-shaped junction (Wang et al 2013a). Therefore, T-shaped junction cannot ensure efficient merging of microdroplets and adding a rectangular microgroove can avoid the synchronism problem and increase the chance of microdroplets merging.…”

Section: Methodsmentioning

confidence: 99%

“…Several methods have been developed to achieve droplet merging and splitting, which can be generally categorized as active (Zagnoni et al 2009; Wang et al 2009; Jung et al 2015; Xu et al 2012; Sesen et al 2014) and passive (Wang et al 2013a; Simon and Lee 2012; Niu et al 2008) methods. Passive methods are generally flow-induced and based on geometry-mediated mechanisms (Christopher et al 2009; Zhou et al 2015; Wang et al 2014).…”

Section: Introductionmentioning

confidence: 99%

“…Passive methods are generally flow-induced and based on geometry-mediated mechanisms (Christopher et al 2009; Zhou et al 2015; Wang et al 2014). It has been demonstrated that droplet merging can be achieved by using flow resistance structures (Xu et al 2011; Tan et al 2004), micro column structures (Niu et al 2008), T-junction structures (Christopher et al 2009; Yang et al 2012), Y-junction structures (Wang et al 2013b), cross-shaped junctions (Wang et al 2013a), and so on. Meanwhile, microdroplet splitting can be obtained at precise locations such as 3D crossing microstructures (Chen et al 2012, 2016), T-shaped junction (Tan et al 2004; Yoon et al 2013; Hoang et al 2013; Link et al 2004), branching channels (Moritani et al 2011; Zhou et al 2015), and artificial obstacle inside channels (Chung et al 2010; Li et al 2014; Protière et al 2010).…”

Section: Introductionmentioning

confidence: 99%

“…Meanwhile, microdroplet splitting can be obtained at precise locations such as 3D crossing microstructures (Chen et al 2012, 2016), T-shaped junction (Tan et al 2004; Yoon et al 2013; Hoang et al 2013; Link et al 2004), branching channels (Moritani et al 2011; Zhou et al 2015), and artificial obstacle inside channels (Chung et al 2010; Li et al 2014; Protière et al 2010). Taking advantage of fluid dynamics in elaborately designed microchannels, the passive methods require no electrodes and have advantages of low contamination of inter-droplet (Wang et al 2013a; Simon and Lee 2012). Therefore, better understanding of the microdroplet flow characteristics is particularly important for passive methods of droplet manipulations.…”

Section: Introductionmentioning

confidence: 99%

“…However, there are only a few qualitative visualization studies on the velocity vector field of microdroplets during merging and splitting using micro-PIV (Wang et al 2013a, b; Liu et al 2015; Jin and Yoo 2012). Systematic quantitative studies for better understanding of the fluid dynamic characteristics of microdroplet merging and splitting are needed.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

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

Shen

Liu

et al. 2017

Microfluid Nanofluid

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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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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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

Shen

Liu

et al. 2017

Microfluid Nanofluid

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Advances in Microfluidics Applied to Single Cell Operation

Zhu

Chu

Wang

2018

Biotechnology Journal

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The field of microbiology have traditionally been concerned with and focused on studies at the population level. Microfluidic platforms have emerged as important tools for biology research at a small scale, even down to a single cell level. The spatial and temporal control of cells and stimuli transported by microfluidic channels in well-designed microsystems realized the studies of specific cells in a controlled microenvironment. The true cellular physiology responses, which are obtained mostly by inference from population-level data, could be revealed in this way. Nowadays, significant applications like cell culture, analysis, sorting, genomics, and proteomics at the single cell level have been achieved in microfluidic chips. Highly integrated microfluidic systems with complete bio-analytic functions are also coming forth and of great promise for single cell related physiology, biomedical, and high throughput screening research. Herein, the leads of technologies applied to single cell operation are reviewed. Challenges and potentials of these works are also summarized, to highlight fields for further research.

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Visualization study on coalescence of droplets with different sizes in external liquid

Shen

Liu

et al. 2017

Can J Chem Eng

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We experimentally investigate the coalescence between two droplets with different sizes in the surrounding water via high‐speed visualization. We identify three coalescence patterns by clarifying the dynamic interface evolutions, including liquid bridge evolution, capillary wave propagation, and pinch‐off behaviours. The results indicate that the coalescence patterns are directly related to the propagation of capillary waves on the coalescent droplet, which is governed by the competition among the capillary force, viscous force, and inertia involved in the draining from the original droplets into the liquid bridge. The external water can efficiently damp the oscillation in capillary wave propagation after the coalescence. In the inertial regime after the droplet coalescence, the evolution of liquid bridge is observed to follow a linear scaling law, when the capillary force induced by the azimuthal interface of the liquid bridge drives the liquid bridge expansion. Accordingly, a phase diagram is organized to characterize these coalescence patterns depending on Ohnesorge number, relative viscosity between external water and droplet, and size ratio between two coalesced droplets.

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Coalescences of microdroplets at a cross-shaped microchannel junction without strictly synchronism control

Cited by 31 publications

References 36 publications

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

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

Advances in Microfluidics Applied to Single Cell Operation

Visualization study on coalescence of droplets with different sizes in external liquid

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