Surface Modification of Stainless Steel used for Medical Applications by Thin Film Deposition Using Microwave Plasma Enhanced Chemical Vapor Deposition

Abstract

Plasma Surface Modification (PSM) is an effective and an economical technique for many materials used in biomedical applications. A microwave Plasma Enhanced Chemical Vapor Deposition (PECVD) system (with 2.45 GHz frequency and 540 W power) was constructed for deposition of polymer-like thin films on 304L stainless steel and glass slide substrates using benzene and argon as precursor and carrier gas respectively. The surface properties of the deposited films such as chemical structure, wettability and morphology were characterized by Fourier-Transform Infrared spectroscopy (FTIR), Water Contact Angle (WCA) measurement and Field Emission Scanning Electron Microscopy (FESEM), respectively. Profilometry was used to determine the deposition rate. The effects of plasma deposition parameters (working pressure, deposition time and negative voltage bias) on the deposited films properties were investigated. FTIR analysis showed that the structure of the deposited thin film changed; in which the C≡C absorption bands became more prominent on decreasing the working pressure. A decrease in the absorption intensity for most of the stretch bands was recorded upon applying a negative voltage bias. All the treated samples registered reduced WCA below 90°; their hydrophilic surfaces became more wettable. The deposition time was found to have had the greatest influence on the rate of film deposition and the WCA measured. Wettability was successfully adjusted through plasma parameters, enabling the production of coatings suitable for specific medical applications, such as implants.