Is antibacterial smartphone glass any use?

New smartphone screens can kill bacteria - in theory

Image: Corning

Around this time every year, technology companies large and small gather for a few days of ridiculously large televisions, peculiar inventions (bluetooth fork anybody?) and loud advertising stunts. I am, of course, talking about the Consumer Electronics Show (CES) that is well under way in Las Vegas, and often you’ll find that what’s announced in Vegas, stays in Vegas. I’m not one to get involved in who’s-got-the-biggest-and-bendiest-television contests, but every now and again something piques my interest. This year it comes from an unlikely source – the glass maker, Corning.

You may not have heard of Corning, but chances are you might be carrying a slab of them in your pocket in the form of their popular Gorilla Glass product. Gorilla Glass can be found adorning the featureless black faces of many of the most popular smartphones, and is much tougher than normal glass. Since the original that adorned the first iPhone in 2007, Corning have improved on the recipe, creating stronger and stronger panels, and at CES 2014 they announced a new avenue of protection all together.

Having won the battle with your keys and other pocket shrapnel, Corning have turned on an even smaller enemy: bacteria.

Their new Antimicrobial Gorilla Glass takes the fight to bacteria, fungi, moulds, mildew and algae, and Corning’s press releases trumpet a 99.9% reduction in bacteria. It works by incorporating silver ions – well-known to have antimicrobial properties – into the structure of the glass.

Where'd you go? Corning reports 99.9% effectiveness.

Where’d you go? Corning reports 99.9% effectiveness.

The company’s own tests show that this new flavour of Gorilla Glass is just as strong and scratch resistant as its grime-ridden siblings. However, it is ever so slightly less clear: those silver ions block a small proportion of the light at the red end of the spectrum, but not enough to notice a difference in real world use.

So far so CES

Call me cynical, but I don’t like taking a press release at its word. I saw that 99.9% figure and thought it was just a bit too good to be true, and delving a little deeper into the research behind this glass throws up a number of things that are conspicuously absent from the Corning sales pitch.

Is that a stag beetle?: Corning's own research shows the necessity for a layer of water, even if their press releases don't.

Is that a stag beetle? Corning’s own research shows the necessity for a layer of water, even if their press releases don’t.

For starters, the antimicrobial effect actually takes quite a while. In laboratory testing, the glass had to be left for two to four hours to get that 99.9% decrease. It’s not going to kill bacteria from your grubby little hands on impact then, though that’s hardly a deal breaker. Your phone could preen itself while you sleep, getting itself all clean and ready to face the day – if, of course, your idea of clean is covered in the carcasses of an army of bacteria, fungi and moulds.

How well it works might depend on something a little odd though: how damp your room is. You see, Corning’s research shows that the ability of the silver ions to kill bacteria drops off rapidly with in a dry environment. Basically, the silver ions need some sort of moisture between themselves and the bacteria to be effective, as shown in the delightfully odd diagram to the right. No, I don’t know what the stag beetle is doing there either.

Antimicrobial glass is interesting idea, there’s no doubt about that. But as to whether it’ll a difference in the real world, we’ll have to wait and see.