Scaling and mechanism of droplet array formation on a laser-ablated superhydrophobic grid

Bahador Farshchian, Javad R. Gatabi, Steven M. Bernick, Gwan-Hyoung Lee, Ravindranath Droopad, Namwon Kim

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3 Citations (Scopus)

Abstract

Superhydrophobic grid patterns were ablated on a hydrophobic polydimethylsiloxane (PDMS) substrate using a nanosecond pulsed laser. The substrate with a wettability contrast (superhydrophobic-hydrophobic) was vertically immersed in a pool of water and withdrawn at different speeds to form droplet arrays spontaneously. The size of droplets was tuned by controlling the withdrawal speed (Sw), which resulted in different contact line speeds on non-irradiated cell (NIC) and laser-irradiated grid (LIG) areas with different surface properties of no-slip and partial-slip conditions, respectively. The ratio of the contact line speeds on NIC and LIG areas (SNIC/SLIG) decreased exponentially with the withdrawal speed, leading to formation of larger droplets on NIC. A geometric scaling model predicted the size of droplets formed on NIC arrays over a range of contact line speeds on NIC and LIG, the ratio of the contact line speeds, the withdrawal speed, and the size of NIC.

Original languageEnglish
Pages (from-to)49-55
Number of pages7
JournalColloids and Surfaces A: Physicochemical and Engineering Aspects
Volume547
DOIs
Publication statusPublished - 2018 Jun 20

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All Science Journal Classification (ASJC) codes

  • Surfaces and Interfaces
  • Physical and Theoretical Chemistry
  • Colloid and Surface Chemistry

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