October 20, 2012, 7:39 AM — When multitudes of Windows 8 users start playing with newly purchased hardware in the coming weeks and months, they'll encounter an indignity that once afflicted only smartphone and tablet users: dirty, smudgy, fingerprint-riddled touchscreens.
Ah, yes, the dreaded smudge. It's a problem we've all come to grudgingly accept on mobile device screens, but PC users generally aren't so accepting of people touchinglet alone leaving fingerprints ontheir desktop displays.
If Microsoft executive Keith Lorizio has his way, some 400 million Windows 8 devices will be active by July 1, 2013. Lorizio was surely including nontouch legacy machines when he made this optimstic declaration last week, and Microsoft has already backed away from Lorizio's comments. But the fact remains that desktop computing is about to get very, very dirty.
So just what is the tech industry doing to head off the collision between PC screens and fingers? Or will desktop users simply resign themselves to a life where dirty screens become the new normal?
If we look to the mobile industry for answers, we see that accessory makers are taking the lead in fingerprint control, answering consumer demand for products that protect phones and tablets from not just smudges, but cracks.
Meanwhile, the hardware manufacturers and their touchscreen suppliers have so far not invested heavily in new science that might stop screen smudging. Rather, they're taking a much more measured, less expensive approach.
Our impression is that smudge-proof touchscreens are still pretty far from becoming commercially available, says IDC tablets and displays analyst Linn Huang. Right now the most elegant solution available is the manufacturers including a free, small terrycloth to use to wipe the screen with each tablet they ship.
Nor are computer manufacturers investing heavily in in-house research that might lead to an effective smudge-resistant surface. Instead, this type of research is happening in universities like Northwestern and MIT, and in various institutional research facilities around the world, such as the Max Planck Institute in Germany and GE Global Research.
Two approaches to resisting smudges
Researchers pursue two strategies for making better oleophobic screens (oleophobic literally means lacking affinity for oils). Some scientists try to advance the chemical treatment approach now used by Apple and others, while others work on applying new physical textures on screen surfaces, textures that are unfriendly to oil and liquid.
Apple was the first large tech brand to apply an oleophobic chemical treatment to the screens of a major product line. The glass screen of the iPhone 3GS was covered with an organic, carbon-based polymer that prevents oil from the skin from sticking to the screen. Instead, the oil (from the user's fingers, cheek, ear, or nose) stays bonded together in droplets, but not bonded with the screen.
Apples solution didnt rid the phone of fingerprints and smudges very effectively, but Apple has stuck with its oleophobic surfaces. New iPhones and iPads ship with oleophobic screens. And the company has certainly invested in research on oil-resistant screens: In February 2011, Apple filed a patent on a special process for applying an oleophobic polymer to the surface of a touchscreen.
Physical screen texturing
The most promising research in oleophobic surfaces involves the physical texturing of screen surfaces. Last December, Max Planck Institute researchers published a paper in the journal Science saying that regular sootthe carbon residue released from a burning candlecan create a rough, oil-resistant surface.
The researchers coated a slide with candle soot, then covered the layer of carbon residue with a layer of silica structures and baked the whole thing at 1112 degrees Fahrenheit, which made the layer of soot transparent.
During tests afterward, the researchers found that oil and dirt particles were repelled by the surface, that they bounced right off the surface of the slide, and did not break apart and scatter about.
Not only did the surface seem to work exceptionally well against fingerprinting, but it was a relatively cheap and simple solution. The only problem was that the surface wasnt very robust and stable and could easily be scratched off.
Hybrid approach holds most promise
The most promising attempts to create the transparent, oleophobic surfaces that touchscreen makers need use a hybrid approach. Simply using chemicals will not get it done; what is needed is a dramatic combination of chemical treatment and texturing, says Neelesh A. Patankar, professor of theoretical and applied mechanics at Northwestern University.
Patankar says (and others agree) that the research with the best chance of leading to a real nonsmudge touchscreen is a hybrid solution being developed by a pair of MIT researchers named Gareth McKinley and Bob Cohen.
The two began a project in the mid-2000s developing liquid-resistant surfaces for the Air Force, which wanted to make materials like O-rings resistant to liquids like jet fuel. Jet fuel, McKinely explains, is a liquid with low surface tension, which means, in very simple terms, that it forms droplets easily.
Liquids like fingerprint oil and sweat, as it happens, also have low surface tension, because theyre both full of bodily secretions like lipids and fatty acids, McKinley says. This is why they are so hard to remove, he says. They want to spread over everything.
The suggestion that McKinleys and Cohens surface treatment might repel finger oil and sweat caught the attention of the computer industry. After we released a couple of research papers in 2007 and 2008 describing our results, we immediately began getting calls from technology companies, McKinley explains. Some in the tech industry saw in the research a possible opportunity to make smudge-resistant touchscreens.
McKinley and Cohen are developing techniques for texturing surfaces with nanofabricated structures that form a forest of microscopic structures that look like tiny round platforms held up from below by thin pedestals. The structures are only about 200 nanometers in size; this is smaller than the wavelength of light, making them potentially transparent, McKinley says.
Theoretically, the tiny nail-shaped structures could be spaced at just far enough apart to prevent the liquid and oil droplets resting on top from combining with other droplets and spreading out. This coalescence and spreading out into a thin oily film is what causes surface smudging and smearing.
Today, McKinley says, he and Cohen in conjunction with another MIT professor, George Barbastathis, have successfully developed a highly transparent surface texture and chemical treatment that repels water, but doesnt yet effectively repel finger oil. Nailing that oil-resistant quality, however, is probably just a matter of time.