Abstract
This paper presents the fabrication of metallic micro-mushroom re-entrant structures and the characterization of their hydrophobicity and oleophobicity. Five different microstructure geometries are introduced, with typical feature sizes in the range of 10-100 μm. These microstructures are realized in steel, and are fabricated over the cm-scale using micro electrical discharge machining (mEDM). The liquid repellency of these surfaces is characterized using droplets of either water (surface energy γlg= 72.4 mN m-1), RL-68H oil (γlg= 28.6 mN m-1), or Isopropanol (IPA) (γlg= 21.7 mN m-1). The water droplets form nearly perfect spheres, with contact angles in the range 146-162°, and contact angle hysteresis of 19-35°. The oil droplet contact angles are in the range 106-152° and the IPA contact angles are in the range 75-123°. Strong re-entrant features and close spacing are necessary to support a fully non-wetting state for use with oil and IPA. Water forms the highest contact angles with narrow, post-like, and widely spaced micro-mushroom geometries.
Original language | English (US) |
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Article number | 095020 |
Journal | Journal of Micromechanics and Microengineering |
Volume | 24 |
Issue number | 9 |
DOIs | |
State | Published - Sep 1 2014 |
Keywords
- IPA
- RL-68H
- hydrophobicity
- micro electrical discharge machining
- oleophobicity
- re-entrant structures
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Mechanics of Materials
- Mechanical Engineering
- Electrical and Electronic Engineering