Combination of laser patterning and nano PTFE sputtering for the creation a super-hydrophobic surface on 304 stainless steel in medical applications

Abstract

Subsequent host tissue responses to implanted biomaterials that occur immediately after implantation are highly determined by surface events between tissue-implant interfaces and in contact biological fluids. These events are directly affected by biomaterial surface features. The surface of the 304 stainless steel as a high used metallic biomaterials in blood contact medical devices need to hemocompatibility improvement. The hemocompatibility features of the surface are affected by various factors, including physical and chemical properties, particularly wettability. A high level of surface hydrophobicity helps to enhance the hemocompatibility. For this, many surface engineering techniques are used to modify and control surface wettability behavior that can be adapted to improve the hemocompatibility and overall performance of biomaterials. In the present study, a laser patterning model is applied for creation of parallel micro-grooves on the surface of 304 stainless steel in first stage. Secondly, a fluorocarbon thin film has been deposited on the inscribed surface of the steel using polytetrafluoroethylene (PTFE) sputtering. The results show that, by creating a micro-groove pattern on the steel surface, the wettability behavior of the surface will also change and the contact angle will be increased from 80° to almost 111°. Moreover, the deposition of a polymer thin film has led to a decrease in surface energy and, thereby, an increase in hydrophobicity and making a contact angle of 149°. From these finding, it can be concluded that, with simultaneous use of topography and surface chemistry changes, the wettability behavior of the surface has been increased and a high and appropriate level of hydrophobicity has been achieved consequently, that is suitable for hemocompatibilty of blood-contact devices. © 2017 Elsevier B.V.