Stainless steel and aluminum are widely used for a wide range of applications. In particular, in many cases their surfaces require the modification of specific surface properties such wettability. In this frame, the control of wetting properties has been the subject of considerable interest due to the potential applications that may be derived, including self-cleaning, anti-icing, and fluid transport. The wettability of a surface can be controlled either by altering the surface chemistry, the topography, or both. The objective of this study is to examine the impact of diverse radial geometries on the transportation of droplets to the symmetry center of surface structures.

Micro-structured surfaces were fabricated in stainless steel and aluminum plates using direct laser writing with a pulsed picosecond laser source operating at 532 nm wavelength. The designs that were subjected to testing included simple concentric circles with a periodic increase of their radius, resulting in profiles with periods of 20, 30 and 40 µm. In addition, pillar-like structures circularly arranged were fabricated by adding concurrent lines to the center while maintaining a constant angle between the lines, of 3° and 5° degrees. To create more complex geometries, intermediate divisions in the pillars were introduced when the width of those exceeded a specified threshold, maintaining the pillars dimensions within defined limits.