Authors: A. Athanassiou
Affilation: Center for Biomolecular Nanotechnologies @ UNILE, IIT, Italy
Pages: 608 - 611
Keywords: UV induced wettability, microfluidic channels, TiO2-based polymeric nanocomposites
PMMA coatings enriched with colloidal TiO2 nanorods are found to exhibit a remarkable increase in their water wettability when irradiated with UV laser light. The effect can be completely reversed using successive storage in vacuum and dark ambient environment. By exploiting the enhancement of the nanocomposites hydrophilicity upon UV irradiation, we prepare wettability gradients along the surfaces by irradiating adjacent surface areas with increasing time. The gradients are carefully designed to achieve directional movement of water drops along them. This kind of samples are very versatile and can also be incorporated in more complicated systems and devices. For this purpose, hybrid channels have been realized using a PMMA/TiO2 base, on which water drops move, confined by three PDMS walls. We found an enhancement in water flow when the base is gradually irradiated with UV light for increasing time to realize a wettability gradient, compared to standard PDMS or PMMA channels, since spontaneous drop movement occurs inside the channel.