Liquid marble coalescence via vertical collision

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Author(s)
Jin, Jing
Ooi, Chin Hong
Dzung, Viet Dao
Nam-Trung, Nguyen
Year published
2018
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Show full item recordAbstract
The coalescence process of liquid marbles is vital to their promising roles as reactors or mixers in digital microfluidics. However, the underlying mechanisms and critical conditions of liquid marble coalescence are not well understood. This paper studies the coalescence process of two equally-sized liquid marbles via vertical collision aided by dielectrophoretic handling. A liquid marble was picked up using the dielectrophoretic force and then dropped vertically onto another liquid marble resting on a hydrophobic powder bed. The whole collision process was recorded by a high-speed camera and the recorded images were then ...
View more >The coalescence process of liquid marbles is vital to their promising roles as reactors or mixers in digital microfluidics. However, the underlying mechanisms and critical conditions of liquid marble coalescence are not well understood. This paper studies the coalescence process of two equally-sized liquid marbles via vertical collision aided by dielectrophoretic handling. A liquid marble was picked up using the dielectrophoretic force and then dropped vertically onto another liquid marble resting on a hydrophobic powder bed. The whole collision process was recorded by a high-speed camera and the recorded images were then analysed to derive the generalised conditions of liquid marble coalescence. By varying the marble volume, impact velocity and offset ratio in the experiments, we concluded that liquid marble coalescence may occur through the coating pore opening mechanism. We quantitatively measured the radius change versus time of the liquid neck formed between two coalescing marbles and estimated the maximum deformation of impacting marbles before rupture in rebound cases. We also qualitatively described the redistribution of coating particles at the impact area during coalescence as well as the consequent ejection of particles. Finally, we summarised the critical conditions for liquid marble coalescence, providing a frame for future applications involving liquid marbles as micromixers and microreactors.
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View more >The coalescence process of liquid marbles is vital to their promising roles as reactors or mixers in digital microfluidics. However, the underlying mechanisms and critical conditions of liquid marble coalescence are not well understood. This paper studies the coalescence process of two equally-sized liquid marbles via vertical collision aided by dielectrophoretic handling. A liquid marble was picked up using the dielectrophoretic force and then dropped vertically onto another liquid marble resting on a hydrophobic powder bed. The whole collision process was recorded by a high-speed camera and the recorded images were then analysed to derive the generalised conditions of liquid marble coalescence. By varying the marble volume, impact velocity and offset ratio in the experiments, we concluded that liquid marble coalescence may occur through the coating pore opening mechanism. We quantitatively measured the radius change versus time of the liquid neck formed between two coalescing marbles and estimated the maximum deformation of impacting marbles before rupture in rebound cases. We also qualitatively described the redistribution of coating particles at the impact area during coalescence as well as the consequent ejection of particles. Finally, we summarised the critical conditions for liquid marble coalescence, providing a frame for future applications involving liquid marbles as micromixers and microreactors.
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Journal Title
Soft Matter
Volume
14
Copyright Statement
© 2018 Royal Society of Chemistry. This is the author-manuscript version of this paper. Reproduced in accordance with the copyright policy of the publisher. Please refer to the journal website for access to the definitive, published version.
Subject
Physical sciences
Chemical sciences
Engineering
Microelectromechanical systems (MEMS)