Development of metallic surfaces for the reduction of bacterial and viral contamination

Healthcare-associated infections (HAIs) pose a significant global issue, impacting patient well-being and healthcare costs. Contaminated surfaces are critical in the infection spread chain, especially for resilient pathogens. Cu and its alloys are promising antimicrobial materials, exhibiting superior effectiveness against microbes compared to stainless steel and polymers. While the antimicrobial properties of bulk Cu are well-established, applying thin Cu-based foils to high-touch surfaces offers a simple and cost-effective solution. However, to ensure long-term effectiveness in real-world applications, challenges related to applicability, durability, tarnishing from frequent contact, and environmental corrosion must be addressed. In this study, we explored the development of Cu-based thin foils (13 to 27 μm thick) for hygiene-sensitive environments. We evaluated the trade-off between mechanical and corrosion properties, along with the antimicrobial behaviour essential for infection control. Cu15Zn and Cu18Ni20Zn alloys were compared to pure PHC Cu, which represented the benchmark. The influence of annealing treatment was also analyzed, comparing recrystallized (R+A) and non-recrystallized (R) Cu foils. Antimicrobial activity was assessed using a simulated real-touch protocol with critical pathogens, including SARS-CoV-2, K. pneumoniae, S. aureus, C. auris, and C. albicans. Wear resistance was evaluated through scratch and microscale abrasion tests (MSAT), alongside microstructural analysis (PFIB-EBSD) and mechanical testing methods, including Bulge Testing (BT) and Instrumented Indentation Testing (IIT). To simulate prolonged use, accelerated ageing in a climatic chamber was conducted to study surface modifications and anti-biofilm activity against P. aeruginosa. Furthermore, we explored enhancing corrosion resistance while maintaining antiviral activity by applying an organosilane coating (PropS-SH). These studies revealed that Cu-based foils demonstrated significant antimicrobial activity under simulated human contact conditions: Cu15Zn foils offer the best balance of durability and antimicrobial properties, while Cu R+A is ideal for short-term, easily replaceable applications. These materials could be highly effective in infection-prone areas such as ICUs and patient washrooms.