Effectiveness of Cold Spray Copper as an Antimicrobial Coating

A comparative study of the antimicrobial effectiveness of three copper surfaces was performed using three metal spray techniques, specifically, plasma spray, wire arc spray and cold spray. The surfaces were then inoculated with meticillin-resistant Staphylococcus aureus (MRSA) and subsequent to a two hour exposure, the surviving MRSA were assayed and the results compared. The differences in the microstructural characteristics produced by the three spray methods were examined in order to explain the mechanism that caused the observed differences in MRSA killing efficiencies. The cold spray deposition process was significantly more effective than the other thermal spray techniques. It was determined that work hardening caused by the high velocity particle impacts created by the cold spray process results in a microstructure that enhances ionic diffusion. It has been well documented that copper ion exchange are principally responsible for antimicrobial activity. This study demonstrates the importance of the copper spray application technique. Cold spray results in high dislocation density and high ionic diffusivity. The cold spray process is a mature technology which is currently in use for a variety of applications requiring various metal coatings. The cold spray process can readily apply copper coatings onto touch surfaces fabricated from various materials.