Antibacterial coating for stainless steel

Long-lasting, durable antibacterial alloy coating

The technology

Most medical device surfaces (such as operating scissors and grab rails) are made of stainless steel, which has high strength and toughness, and excellent corrosion resistance.

However stainless steel surfaces have little resistance to microorganism propagation and previous attempts to make stainless steel surfaces resistant to bacteria have proved to have limited durability.

The obvious candidate for antibacterial protection is silver, which has notable antibacterial properties, but its low solubility in stainless steel has been an obstacle to bulk alloying. In addition, current techniques produce a thin layer of silver on a soft substrate – making it difficult to ensure high durability and anti-bacterial properties simultaneously.

Researchers at the University of Birmingham developed a new alloying technique to harden stainless steel surfaces by co-alloying with Nitrogen and Carbon to form a hard wearing surface – and at the same time introducing Silver or Copper into the stainless steel surface.

This novel technique uses active screen plasma (ASP) alloying technology, which generates a highly durable antimicrobial surface by combining a wear-resistant S-phase with nanocrystalline silver or copper and medical grade stainless steel.

The team has conducted a full characterization and a full evaluation of the surface hardness, wear resistance and antimicrobial efficacy of the alloyed surfaces.

Evaluation showed that the silver alloyed S-phase can achieve a 93% reduction in Escherichia coli (E.coli) after 6 hours of contact time.