The Safe Touch research project funded by the Industrial Collective Research (IGF) has succeeded in developing a durable metallic-ceramic coating made of Al2O3 with permanent antimicrobial properties by adding a small amount of copper. According to the Jena-based research institute Innovent e.V., the coating is just a few micrometers thick and can be deposited on all rough surfaces such as metals and temperature-stable plastics in various designs.

Adhesive, abrasion-resistant layers

According to the press release, the new coatings are adhesive and abrasion-resistant, comparable to hard anodizing. The copper particles improve the adhesion and abrasion properties of the Al2O3 coating. The antimicrobial coating is applied using cold plasma spraying. Due to the lower plasma power and process temperature than with conventional plasma spraying, thermally sensitive substrates such as plastics can also be coated. The powders used for this usually have average grain diameters of around 10 to 20 micrometres, which makes the deposition of coatings with a thickness of between 20 and 100 micrometres economical, as Innovent reports.

Antibacterial against E. coli and S. aureus

Their antibacterial effect was tested against E. coli (gram-) and S. aureus (gram+), as well as their antiviral effect using the example of the modified vaccinia virus strain Ankara (MVA) and the murine norovirus (MNV). For this purpose, tests were carried out in accordance with ISO 22196 and ISO 21702, in which the surfaces to be tested were brought into contact with a defined quantity of bacteria or viruses. In the tests, which were designed for contact times of 24 hours, a very good effect was demonstrated after just 60 minutes, according to the report. The effect also remains stable in the long term after tests for mechanical stress (washability) and chemical leaching of the surfaces (eluate test).

For high-risk areas and effective against biofilms

The coatings were developed in collaboration with the research association Dechema Gesellschaft für Chemische Technik und Biotechnologie e.V. (Dechema Society for Chemical Engineering and Biotechnology). The aim was to develop a novel, antibacterial and antiviral, long-term active coating for everyday objects that are regularly touched by hands in their function. This should reduce the risk of transmission of germs, bacteria and viruses through touch/physical contact. The coatings can also be used in high-risk hygiene areas, even in places that are difficult to access and problematic for cleaning routines. Last but not least, the coating of wire mesh and filter ceramics with the new material minimizes biofilm formation, which leads to an improvement in usage properties and service life.

These coatings expand the range of available surfaces in the fight against harmful viruses and bacteria, as Innovent states. By applying permanently effective coatings, cleaning processes can be made more efficient and the use of chemical disinfectants can be reduced.