Self-propelled droplets on heated surfaces with angled self-assembled micro/nanostructures

Corey Kruse, Isra Somanas, Troy Anderson, Chris Wilson, Craig Zuhlke, Dennis Alexander, George Gogos, Sidy Ndao

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

Directional and ratchet-like functionalized surfaces can induce liquid transport without the use of an external force. In this paper, we investigate the motion of liquid droplets near the Leidenfrost temperature on functionalized self-assembled asymmetric microstructured surfaces. The surfaces, which have angled microstructures, display unidirectional properties. The surfaces are fabricated on stainless steel through the use of a femtosecond laser-assisted process. Through this process, mound-like microstructures are formed through a combination of material ablation, fluid flow, and material redeposition. In order to achieve the asymmetry of the microstructures, the femtosecond laser is directed at an angle with respect to the sample surface. Two surfaces with microstructures angled at 45° and 10° with respect to the surface normal were fabricated. Droplet experiments were carried out with deionized water and a leveled hot plate to characterize the directional and self-propelling properties of the surfaces. It was found that the droplet motion direction is opposite of that for a surface with conventional ratchet microstructures reported in the literature. The new finding could not be explained by the widely accepted mechanism of asymmetric vapor flow. A new mechanism for a self-propelled droplet on asymmetric three-dimensional self-assembled microstructured surfaces is proposed.

Original languageEnglish (US)
Pages (from-to)1417-1424
Number of pages8
JournalMicrofluidics and Nanofluidics
Volume18
Issue number5-6
DOIs
StatePublished - May 1 2015

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Keywords

  • Boiling and evaporation
  • Directional surfaces
  • Droplet motion
  • Femtosecond laser
  • Leidenfrost
  • Ratchet

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Materials Chemistry

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