Plasma-treated switchable wettability of parylene-C surface

The wetting behavior of biomaterials is of great importance for the issues such as biofouling control and biocompatibility improvement. Therefore, tailoring of their wettability is particularly useful and has been attracting a lot of interests. This paper focuses on the modification of surface wettability on the parylene-C film, which is exclusively used as a coating material for insulating implantable biomedical devices. The oxygen (O₂) and sulfur hexafluoride (SF₆) plasma were applied to treat parylene-C samples successively. Super hydrophilic (~0°) and super hydrophobic (~160°) surfaces were achieved under very low plasma power. The Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) results strongly suggest that the surface roughness and the incorporation of oxygen or fluorine bonds on the surface are the two main factors accounting for the significant change of wettability. Moreover, the parylene-C surface has been proved to be switchable between super hydrophilicity and hydrophobicity by applying only an additional short O₂ or SF₆ plasma treatment, which greatly benefits the use of parylene-C in a wide range of biomedical applications.