Expanded polytetrafluoroethylene (ePTFE) as an artificial dura mater is often associated with cerebrospinal fluid (CSF) leakage after skull base surgeries, because ePTFE is not able to adhere to both fibrin glue and tissue. To improve these critical properties, the surface of ePTFE was modified with ion beam irradiation and the effects of its biocompatibility were investigated. ePTFE sheets were irradiated with Ar⁺ ions with a fluence of 5×10¹⁴ ions/cm² and an energy of 150 keV. CSF leakage was observed for pristine ePTFE, while CSF leakage did not occur for ion beam irradiated ePTFE that adhered to surrounding tissues. Brain artery aneurysms are frequently treated using microsurgical clipping of the aneurysm neck, endovascular coiling of the aneurysm sac, or balloon occlusion of the parent vessel. For some broad-based aneurysms not suitable for these options, ion implantation was utilized to ePTFE wrapping material for treatment of brain aneurysms. We also studied applications for small diameter vessel anastmosis.