Abstract
This paper describes water-repellency and drag forces of hydrophobic wire legs for water-walking robots inspired by a water strider. Recently, many researchers developed bio-inspired water-walking robots. However, the supporting legs of these robots are inferior to those of water striders in water repellency. In this study, helical grooves with various depths were fabricated on the surface of a brass wire using femtosecond laser machining to increase water repellency. Effects of the grooves on contact angles and drag forces were investigated. The experimental results showed that the wire with deep grooves exhibits high water repellency. The drag force acting on the leg was found to obey the drag equation when the reference area was determined considering a dimple and a bump of the surface of water.
