Stainless steel vs. copper in the interior of a CO2 incubator

A study by the Institute for Hygiene and Public Health (IHPH) at the University of Bonn from 2009 demonstrates: copper cannot be unconditionally recommended for the prevention of germs, since there are no reliable findings on the antimicrobial effect of copper surfaces after intensive cleaning and disinfection. Stainless steel remains the material of choice for long-lasting appliances.

Memmert is committed to stainless steel

For many decades now, Memmert has been using high-quality stainless steel for the interiors and outer housing of its ovens, drying ovens, incubators, climate chambers and heating baths. Compared to coated steel plate in particular, the structured stainless steel used to give Memmert appliances their unmistakable appearance is robust, scratch-resistant and can be optimally cleaned with disinfection and cleaning agents. The issue concerning the need to offer interiors made of copper is negated in the study introduced below.

The fight against germs in hospitals

The fight against highly resistant germs in hospitals is one of the great challenges of our times. This has led to a renewed focus on discussions of the oligodynamic (germ-killing) properties of copper. This issue is of continued importance with Memmert as well as the question of whether it makes sense to coat the interior of incubators, and in particular CO2 incubators, with copper. The Institute for Hygiene and Public Health (IHPH) of the University of Bonn has evaluated various research results on the antibacterial qualities of stainless steel and copper in recent years. The overall result shows that the sole use of copper, copper alloys and coatings instead of stainless steel cannot be recommended.

Stainless steel offers outstanding surface properties

The fact that copper as a raw material has an antimicrobial effect has been known since ancient times. Copper emits ions that can penetrate the bacterial cell and destroy it. In contrast to this, stainless steel is inert, so that it hardly reacts at all with materials in its surroundings, and is extremely sturdy with respect to mechanical loads.

The most convincing argument for the use of stainless steel in healthcare is thus based on its surface properties. The scratch and abrasion-resistant, corrosion-free stainless steel is impervious to acids or lyes, and even after many years of using cleaning and disinfection agents still prevents the formation of a biofilm with dangerous residual germs. As infections are above all transmitted via hands and directly via the surfaces with which they come into contact, copper surfaces must also be cleaned constantly. Attempts to reduce the time spent cleaning and disinfecting through the use of copper surfaces have to be decisively rejected for reasons of safety. The Bonn study reveals that the oligodynamic effect of copper or brass surfaces is reduced by dirt or sweat, and in individual cases, even resistances could be detected.

Cleaning changes the structure of copper surfaces

Cleaning copper surfaces with cleaning and disinfection agents in turn leads to greenish discolouring and to a change in the surface structure, making cleaning increasingly difficult and reducing its antibacterial effect. For surfaces that have to be kept sterile over many years and which are subject to continuous mechanical strain through cleaning and disinfection, as is the case in the interiors of incubators, stainless steel still remains the material of choice – always in combination with an effective plan for cleaning, disinfection and sterilisation, to ensure maximum hygiene.