Microstructure and Platelet Adhesion Behavior of Titanium Oxide Films Synthesized by Reactive High-Power Pulse Magnetron Sputtering

Titanium oxide films are promising as a blood-contacting biomedical material. In this paper, titanium oxide films are deposited on a Si (1 0 0) substrate by high-power pulsed magnetron sputtering (HPPMS) at different oxygen flow rates. The microstructure and surface morphology are investigated for a variety of oxygen flow rates mixed with argon gas. The blood compatibility of the films is evaluated using a platelet adhesion experiment, and the quantity and morphology of the adhered platelets are investigated through optical microscopy. The oxygen flow rate is varied from 2 to 10 sccm with a fixed argon flow rate of 60 sccm. The composition of the deposited films was TiO and ${\rm Ti}_{2}{\rm O}$ mixtures at an oxygen flow rate of 2 sccm. An anatase and rutile mixed phase is found at an oxygen flow rate of 4 sccm. The titanium oxide film is in the rutile phase with an increasing oxygen flow rate up to 6 sccm or higher. This suggests that the rutile-structured titanium oxide films could be synthesized by HPPMS without heating the substrate. The titanium oxide films with a rutile structure had a very smooth surface with a minimum surface roughness of 0.3 nm. The result of a platelet adhesion experiment indicates that the rutile phase titanium oxide film showed better blood compatibility. From this point of view, the films synthesized by HPPMS are promising to be as biomaterials showing excellent corrosion resistance and a smoothed surface.