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May 8th, 2012

Corning prepping new anti-microbial glass product

Published on May 8th, 2012 | By: pwray@ceramics.org

Credit: The Corning Leader.

When you walk up to an ATM or an airport kiosk, ever wonder where the prior user’s hands might have been or what they left behind on the touchscreens?

Corning has. Last week, Corning held its annual shareholders meeting, and during the meeting Corning chair and CEO Wendell Weeks, with a little fanfare, announced that the company is developing a glass that kills drug-resistant bacteria and viruses. According to a a video shot by the local newspaper, The Leader, Weeks said that the product is still in development, but can kill 99% of viruses and bacteria it contacts, including methicillin-resistant staphylococcus aureus (MRSA).

Weeks seems to joke a little bit regarding the context for this and about how, with Gorilla Glass now in 600 million devices (the fastest growing product in the company’s history), several people have asked about all the germs that are on Gorilla Glass screens .

I am not sure how big of a problem bacteria and viruses are on smartphones, but, okay, I am not sure there is much benefit in arguing the point. I do get, however, that having this type of glass surface available in medical settings, where seriously nasty germs abound, could be very valuable.

One thing, however, I am not so clear on is how unique or new the Corning product is, or what the problems are with bringing it to market. Back in 2007, AGC Glass announced something similar, claiming, “A world première, AntiBacterial Glass kills 99.9% of bacteria  and stops the spread of fungi, which, with the emergence of antibiotic-resistant bacteria, represents a milestone in the fight against hospital-caught infections.”

This YouTube video (in French with English subtitles) from 2010 suggests the AGC product is based on surface technologies involving titanium dioxide and silver

The video does make some references silver, but If it is true that the antimicrobial action is mainly due to the titania content of the glass, then I suspect it is different from the Corning product.

My suspicions are based on patent about “chemically strengthened glass having antimicrobial properties and to a method of making such glass,” just filed in February by a Corning group that included Nicholas F. Borrelli, David L. Morse, Wageesha Senaratne, Florence Verrier and Ying Wei. Morse, perhaps the most well known of the group, was just named CTO of Corning.

Skimming through the quintet’s patent, it is interesting that they note, “The methods described herein can be used to make antimicrobial glass samples of any thickness. In one embodiment, for example, for use in electronic devices as a touch screen or a touch screen cover glass, for example without limitation, cell phones, computer (including laptops and slates) and ATMs, the glass typically has a thickness in the range of 0.2 mm to 3 mm.”

They go on to report on the antibacterial properties ascribed to silver, but explain that the antibacterial force comes from Ag+1 ions found on the surface of an object, not silver, itself.

Regarding the process they advocate, in brief, they admit that some silver could be introduced as part of a one-step process to chemically strengthen glass, but a one-step process does not leave enough Ag+1 ion to provide sufficient “kill” action, and, “further when the one-step method is used, significant color is produced as a consequence. This color makes the glass unsuitable for use in electronic devices by altering the display, for example, by making it less clear or altering the colors.”

Instead, they go on to describe how they have devised a better two-step process “that allows one to obtain a significantly higher concentration of Ag+1 ions on the surface of the glass which results in a commensurate decrease in the ‘kill’ time … while not producing any undesirable yellow color and therefore achieving the desirable transmittance characteristics.”

So, it is fair to wonder: if one of the key properties of this glass depends on Ag+1 ions on the surface of a glass product, what happens to the surface when one cleans it? Well, they have an answer for that, too. The patent document claims the glass can be cleaned easily with no loss of anti-microbial effectiveness, ” A ‘low surface energy’ coating is applied to the surface of the silver-containing, chemically strengthened antimicrobial glass to impart easy-to-clean properties to the glass surface. The low surface energy coating is a hydrophobic coating that facilitates the ease of cleanability of the surface.”

Thus, I suspect that Week’s discussion of anti-microbial glass is a direct reference to the work of Morse et al.

For anyone interest in Week’s entire presentation (about an hour), the company offers a audio MP3 and a WMA version of his presentation. He starts getting in to the specific vision built of the company built on GG, GG2 around the 33 minute mark, and the anti-microbial glass around 38 minute minute mark.


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