Visible light - induced reversible hydrophilicity of doped metal oxide
micro/nano structured surfaces
A. Loufardaki
1,2 *
, S. Aslanoglou
1,2
, E. Orfanoudakis
1,3
, C. Fotakis
1,2
, E. Stratakis
1,3
1
Institute of Electronic Structure and Laser, Foundation for Research and
Technology-Hellas (IESL-FORTH), Heraklion 70013, Crete, Greece
2
Physics Department, University of Crete, Heraklion 71003, Greece
3
Materials Science and Technology Department, University of Crete, Heraklion 71003, Greece
Control over the wettability of solids, as well as the manufacturing of functional
surfaces with special wetting properties has attracted much interest because of great
advantages given to various applications in daily life, industry and agriculture. This work
reports on the dynamic optical control of the wetting behavior of liquids on hierarchically
structured metal oxide surfaces. These surfaces are produced by irradiating silicon (Si) wafers
with femtosecond laser pulses and subsequently coating them with a thin film of Nitrogen
doped TiO
2
or ZnO by Pulsed Laser Deposition (PLD). The final surface exhibits roughness
at two length scales, comprising micrometer-sized Si spikes decorated with TiO
2
or ZnO
nanoprotusions. We have shown that a liquid droplet on these surfaces can be rapidly and
reversibly switched between hydrophobicity and hydrophilicity by alternating illumination
with visible light and dark storage or thermal heating in ambient conditions (Fig. 1).
Figure 1 : Wettability alternation under visible irradiation and dark storage.
PS2 10
-204-
