Development of surfaces with antibacterial durability through combined S phase plasma hardening and athermal femtosecond laser texturing

Antibacterial textures provide an attractive solution to the problem of cross contamination of foods and healthcare-acquired infections that regularly affect the food and medical industries. However, the functional properties associated with such textures typically arise due to fragile nanoscale features, and unfortunately, there is almost no information available on the longevity of those features or the properties that they bring. Therefore, this study has examined the antibacterial durability of state-of-the-art triangular LIPSS produced using femtosecond pulsed laser texturing on untreated and S phase hardened AISI 316L austenitic stainless steel surfaces. Prior to wearing, the triangular LIPSS were found to have strong antibacterial properties against S. aureus (>90% reduction) and E. coli (>75% reduction). Following large area wearing, the untreated and textured surfaces became dramatically more susceptible (>50% increase) to bacterial colonisation, while almost no change was found on S phase hardened samples (<10% increase). Further testing demonstrated at least two-fold increase in longevity of the properties on the S phase treated surfaces. Therefore, this study demonstrates the underlying issue of antibacterial durability following surface texturing, provides an approach to overcome this problem and, for the first time, measures the antibacterial durability of textured surfaces.