A Novel Diffuse Plasma Jet Without Airflow and Its Application in the Real-Time Surface Modification of Titanium

Real-time modification is a promising method for improving the clinical surface performance of titanium (Ti) implants, which requires a simple structure, short treatment time, and long duration of hydrophilicity. Hence, a novel diffuse jet without airflow was developed in this paper to address these three requirements. The diffuse jet produces cone-shaped plasma with a maximum radial size of 16 mm and a typical characteristic of diffuse discharge. Due to the absence of airflow, the diffuse jet with a simple structure and a mild discharge meets the first requirement. The diffuse jet remains quasiuniform and stable when contacting with metals. The effective modification area is approximately 200 mm ^{2} , which is seven times larger than that of the current plasma jets. A super-hydrophilic surface with the original multilevel microporous structure can be obtained after just 40 s of treatment with the diffuse jet, and remain viable for at least 30 mins, which meets the other two requirements. The carbon-cleaning effect and oxygen-attaching effect of the diffuse jet, along with the higher intensities of the C = O/O-H together with the lower intensities of C-C/C-H after modifications, are responsible for the super-hydrophilicity. Because the slow expansion and the long reaction time of the active particles caused by the absence of airflow, a longer treatment time is more beneficial for the duration of the super-hydrophilicity. The results above successfully meet all the requirements and present a novel efficient method for the clinical real-time surface modification of Ti.