Antimicrobial copper-coatings on temperature labile surfaces deposited with a DC plasma jet operated with air

Summary form only given. Non-thermal plasma jets are currently investigated for applications in plasma medicine. We have investigated the potential of a plasma jet that was originally developed for medical applications. The jet is generated by flowing air through the discharge channel of a microhollow cathode geometry. The temperature of the plasma itself can reach values well above 1000°C but the gas flow is effectively cooling down the expelled afterglow plume to temperatures of about 40°C within a distance of 10-15 mm. We deposited copper on silicon and AcrylnitrilButadien-Styrene (ABS). Respective substrates were placed at a distance of 10 mm and moved through the jet in a meander pattern, covering an area of 2 cm by 2 cm. For an exposure time of 864 s we found a similar distribution of copper deposits for both materials. Individual islets had a size in the range of 50400 nm and interspatial distances of 100-500 nm. SEM images show some distinct differences for coatings on silicon and ABS. In particular smaller deposits on silicon appear crystalline. Conversely, the fringes of deposits on ABS seem to merge with the substrate. XPS-measurements show that the amount of copper deposited scales with operating parameters up to a certain point. The dimensions of the deposition patterns are much smaller than the size of most bacteria. The anticipated antimicrobial effect was confirmed for ABS by an observed reduction of 95% in bacterial growth of Staphylococcus aureus when comparing coated and uncoated samples.