ABSTRACT
Contact surfaces have been identified as one of the main routes for pathogen transmission. The efficacy to kill both viruses and bacteria on touch surfaces is critical to reducing the rampant spread of harmful pathogens. Copper is one such material that has been traditionally used for its antimicrobial properties. However, most contact/touch surfaces are made up of steel or aluminum due to their structural properties. Therefore, coating high-touch components with copper is one possible solution to improve antibacterial efficacy. In this study, copper was coated on both stainless steel and aluminum substrates using a cold spray process which is a fast and economic coating technique. The coated samples in both as-deposited and heat-treated states were exposed to Escherichia coli and Staphylococcus aureus bacteria, and their efficacy was compared with bulk copper plate. It was found that both bacterial cells responded differently to the different coating properties such as coating thickness, porosity, hardness, surface roughness, oxide content, and galvanic coupling effect. These correlations were elucidated in light of various results obtained from antibacterial and bacterial attachment tests, and materials characterizations of the coatings. It is possible to tailor copper coating characteristics to render them more effective against targeted bacteria.
ABSTRACT
In this work, cold-spray technique was employed for rapid coating of copper on in-use steel parts. The primary intention was to alleviate the tendency of SARS-CoV-2 (COVID-19) virus to linger longer on touch surfaces that attract high-to-medium volume human contact, such as the push plates used in publicly accessed buildings and hospitals. The viricidal activity test revealed that 96% of the virus was inactivated within 2-hrs, which was substantially shorter than the time required for stainless steel to inactivate the virus to the same level. Moreover, it was found that the copper-coated samples significantly reduces the lifetime of COVID-19 virus to less than 5-hrs. The capability of the cold-spray technique to generate antiviral copper coating on the existing touch surface eliminates the need for replacing the entire touch surface application with copper material. Furthermore, with a short manufacturing time to produce coatings, the re-deployment of copper-coated parts can be accomplished in minutes, thereby resulting in significant cost savings. This work showcases the capability of cold-spray as a potential copper-coating solution for different in-use parts and components that can act as sources for the spread of the virus.