Substrate curvature gradient drives rapid droplet motion

Making small liquid droplets move spontaneously on solid surfaces is a key challenge in lab-on-chip and heat exchanger technologies. Here, we report that a substrate curvature gradient can accelerate micro- and nanodroplets to high speeds on both hydrophilic and hydrophobic substrates. Experiments f...

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Bibliographic Details
Published in:Physical review letters 2014-07, Vol.113 (2), p.026101-026101, Article 026101
Main Authors: Lv, Cunjing, Chen, Chao, Chuang, Yin-Chuan, Tseng, Fan-Gang, Yin, Yajun, Grey, Francois, Zheng, Quanshui
Format: Article
Language:English
Subjects:
Curvature
Droplets
Free energy
High speed
Liquids
Mathematical analysis
Nanostructure
Solid surfaces
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Summary:Making small liquid droplets move spontaneously on solid surfaces is a key challenge in lab-on-chip and heat exchanger technologies. Here, we report that a substrate curvature gradient can accelerate micro- and nanodroplets to high speeds on both hydrophilic and hydrophobic substrates. Experiments for microscale water droplets on tapered surfaces show a maximum speed of 0.42  m/s, 2 orders of magnitude higher than with a wettability gradient. We show that the total free energy and driving force exerted on a droplet are determined by the substrate curvature and substrate curvature gradient, respectively. Using molecular dynamics simulations, we predict nanoscale droplets moving spontaneously at over 100  m/s on tapered surfaces.
ISSN:0031-9007
1079-7114
DOI:10.1103/physrevlett.113.026101