Friction and Wetting Transitions of Magnetic Droplets on Micropillared Superhydrophobic Surfaces

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Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2017-10-11
Major/Subject
Mcode
Degree programme
Language
en
Pages
1-7
Series
Small, Volume 13, issue 38
Abstract
Reliable characterization of wetting properties is essential for the development and optimization of superhydrophobic surfaces. Here, the dynamics of superhydrophobicity is studied including droplet friction and wetting transitions by using droplet oscillations on micropillared surfaces. Analyzing droplet oscillations by high-speed camera makes it possible to obtain energy dissipation parameters such as contact angle hysteresis force and viscous damping coefficients, which indicate pinning and viscous losses, respectively. It is shown that the dissipative forces increase with increasing solid fraction and magnetic force. For 10 µm diameter pillars, the solid fraction range within which droplet oscillations are possible is between 0.97% and 2.18%. Beyond the upper limit, the oscillations become heavily damped due to high friction force. Below the lower limit, the droplet is no longer supported by the pillar tops and undergoes a Cassie–Wenzel transition. This transition is found to occur at lower pressure for amoving droplet than for a static droplet. The findings can help to optimize micropillared surfaces for low-friction droplet transport.
Description
| openaire: EC/H2020/725513/EU//SuperRepel
Keywords
droplet oscillations, friction, superhydrophobicity, wetting transition
Other note
Citation
Al-Azawi , A , Latikka , M , Jokinen , V , Franssila , S & Ras , R H A 2017 , ' Friction and Wetting Transitions of Magnetic Droplets on Micropillared Superhydrophobic Surfaces ' , Small , vol. 13 , no. 38 , 1700860 , pp. 1-7 . https://doi.org/10.1002/smll.201700860