Laser ablation technology can be applied to fabricate three dimensional micro- and nanostructures. This texturing process is aimed to influence on the proliferation and adhesion of bacteria on the surface by modification of its topography.
For this reason, different topographies combining micro- and nano-texturing (hierarchical structures) have been designed and created by laser ablation technology on the surface of Titanium plates in order to avoid or reduce the proliferation of two different types of bacteria. Surface texturing was carried out by means of a picosecond pulsed laser integrated in a micromachining workstation. This technology allows high structuring speed (up to 2000 mm/s) covering a long surface area (up to 350x350 mm2 for long focal length optics) without moving the scanner. Longer areas can be covered by axis interpolation with the galvanometric scanner.
The hierarchical structures generated by the laser in the Titanium plates consist on pyramidal features at the microscale covered by nanoripples (laser-induced periodic surface structure: LIPSS). Nanoripples are characterized by a period of, approximately, 700 nanometers. These hierarchical structures leaded to a high antibacterial activity for two types of Gram-positive bacteria, with a reduction on the bacteria proliferation above 70% for both of them (assays made under the standard JIS Z 2801:2010/A1:2012). In addition, the structured surface showed a superhydrophobic behaviour with a water contact angle of 150°. The durability of the surface structures was evaluated under abrasion tests, observing that the texturing and the hydrophobic behaviour of the surface (linked to the antibacterial activity) were maintained practically unaltered.