Droplet spreading on a two-dimensional wicking surface.
The dynamics of droplet spreading on two-dimensional wicking surfaces were studied using square arrays of Si nanopillars. It was observed that the wicking film always precedes the droplet edge during the spreading process causing the droplet to effectively spread on a Cassie-Baxter surface composed of solid and liquid phases. Unlike the continual spreading of the wicking film, however, the droplet will eventually reach a shape where further spreading becomes energetically unfavorable. In addition, we found that the displacement-time relationship for droplet spreading follows a power law that is different from that of the wicking film. A quantitative model was put forth to derive this displacement-time relationship and predict the contact angle at which the droplet will stop spreading. The predictions of our model were validated with experimental data and results published in the literature.
Advanced Materials for Micro- and Nano-Systems Programme, Singapore-MIT Alliance, Singapore 117576.
Chang Quan
CQ
Lai
Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576.
Trong Thi
TT
Mai
Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576.
H
H
Zheng
Department of Mechanical Engineering, National University of Singapore, Singapore 117576.
P S
PS
Lee
GLOBALFOUNDRIES Singapore Pte. Ltd, Singapore 738406.
K C
KC
Leong
Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576.
Chengkuo
C
Lee
Advanced Materials for Micro- and Nano-Systems Programme, Singapore-MIT Alliance, Singapore 117576 and Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576.
W K
WK
Choi