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Researchers at Spain’s Institute of Photonic Sciences and the US’ Corning Research and Development Corporation have designed and implemented a transparent nanostructured copper surface (TANCS) that is non-conductive and resistant to the growth of certain bacteria.
Their goal is to provide a solution for personal and multi-user touch screens such as tablets and mobile devices, something that had been hard to achieve using copper because coatings produced from the red metal are predominantly opaque.
In a recent study published in the journal Communications Materials, the scientists explain that the fabrication process of this surface involved depositing an ultra-thin copper film with a nominal thickness of 3.5nm onto a glass substrate. Then, they used a rapid thermal annealing process to form dewetted Cu nanoparticles with optimal size and distribution.
This specific design and method provided an antimicrobial effect, transparency, colour neutrality, and electrical insulation. Finally, additional layers of SiO2 and fluorosilanes were deposited on top of the nanoparticles, providing environmental protection and improved durability properties with use-test cases.
Subsequently, the study authors examined the fabricated coating morphology, optical response, antimicrobial efficacy, and mechanical durability. The TANCS showed the ability to eliminate over 99.9% of Staphylococcus Aureus present in the tested surfaces within two hours, under stringent dry test conditions.
Moreover, the substrate demonstrated optical transparency allowing for 70-80% light transmission in the visible range (380-750nm) and colour neutrality. Finally, the surfaces showed to have a prolonged effectiveness with use-test cases, maintaining their antimicrobial activity even after a rigorous wipe-testing procedure.
“This is a great example of creating a multi-attribute product while co-optimizing the attributes high efficacy antimicrobial properties that work under dry test conditions for touch-enabled, display use test cases,” Wageesha Senaratne, a researcher at Corning and leading co-author of the study, said in a media statement. “Our goal was to show the connections between biological performance and physical attributes and provide further guidance for future research.”
For Senaratne and her colleagues, this new approach of considering the dewetting process opens a variety of new possibilities to exploit some specific properties of metals while being able to thoughtfully change the others.
“Here, for example, we were able to preserve the powerful antimicrobial effect of the copper while obtaining transparency and insulation despite the use of a metal,” said Alessia Mezzadrelli, co-author of the study.
While further development is necessary for full-fledged commercial deployment, the researchers believe this is a step in the right direction to enable antimicrobial touch screens for public or personal displays.
