Controls in wettability of TiOx films for biomedical applications

The interaction between metal surface and cell/tissue is important for the biocompatibility of metallic implants, and surface modification has been studied extensively to alter its surface characteristics, and improve biocompatibility. Titanium oxide (TiOx) films were deposited by electron-beam evaporation system using TiO2 as a source material. The films deposited by various thickness and growth rate were investigated by X-ray diffraction patterns, field emission scanning electron microscopy, X-ray photoelectron spectra and atomic force microscopy. TiOx films were etched subsequently by different plasma to obtain different surface morphology. The structure of TiOx film was uninfluenced after being etched, but the composition of films was changed from nonstoichiometric to stoichiometric due to etching process, and the surface roughness of TiOx films was decreased. TiOx films became highly hydrophilic by ultraviolet (UV) irradiation and returned to its original hydrophobic state by visible-light (VIS) irradiation. The wettability of the TiOx surface was enabled to convert between hydrophilic and hydrophobic reversibly by alternative UV and VIS irradiation. TiOx films were further modified by self-assembled monolayer (SAM) of silanes.