NailO turns your fingernail into a tiny trackpad

A wearable input device in the form of a nail sticker could make it easy to control a computer with a subtle swipe. Could nail calls be the new butt dials?

Leslie Katz Former Culture Editor
Leslie Katz led a team that explored the intersection of tech and culture, plus all manner of awe-inspiring science, from space to AI and archaeology. When she's not smithing words, she's probably playing online word games, tending to her garden or referring to herself in the third person.
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Leslie Katz
3 min read

NailO: Much more than decorative nail art. Cindy Hsin-Liu Kao

Swiping away on a smartphone during a meeting could, in many cases, be considered bad business behavior. But what if you could subtly tap your thumbnail with your index finger to quickly send an important text or email, a gesture so tiny on no one would notice?

Give a wave to NailO, a nail-mounted gestural input surface out of MIT Media Lab that allows discreet one-handed input via a surface that's always readily available. Its creators imagine NailO as particularly, yes, handy in situations where gestures or speech input could be considered impolite or inappropriate, or both hands are busy.

Inspired by decorative nail stickers, NailO involves multilayered miniaturized hardware that wirelessly transmits data, via Bluetooth, to a mobile device or PC.

The team developed an application that lets engineers navigate printed circuit board designs on devices while both hands are occupied with soldering. NailO

That means you're walking around with capacitive sensors, a battery and three separate chips -- a microcontroller, a Bluetooth radio chip and a capacitive-sensing chip -- packed onto your fingernail. But the setup is lightweight, its creators insist. And it can be topped with nail art, so it's not as odd-looking as it might sound.

In fact, the researchers picture a commercial version of NailO with a detachable surface membrane that wearers could swap out to match their outfits.

"It's very unobtrusive," explained Cindy Hsin-Liu Kao, an MIT graduate student and lead author on a paper describing the system. "When I put this on, it becomes part of my body."

The research team plans to present its work at the upcoming CHI 2015, a conference on human-computer interaction in Seoul. The paper describing NailO has already earned a "Best of CHI" honorable mention.

A copy of the study provided to CNET's Crave blog describes an application that lets engineers zoom in on printed circuit board designs while both hands are busy soldering. The team also came up with a mobile typing application that lets users employ nail swipe gestures to input punctuation or emoticons without having to alternate keyboard views.

In tests of their system involving five gestures, NailO detected gestural inputs in real time with more than 92 percent accuracy, according to the paper. The scientists acknowledge that for NailO to succeed, it must ignore accidental gestures (imagine the butt dial being replaced by the nail call). To avoid this, they propose a 2-second activation press before any other gestures can be performed.

For the initial prototype, the team built their sensors by printing copper electrodes on sheets of flexible polyester. That allowed them to experiment with a range of electrode layouts, but now they're using off-the-shelf sheets of electrodes like those found in some touchpads.

"The hardest part was probably the antenna design," said Artem Dementyev, a graduate student in media arts and sciences and the paper's other lead author. "You have to put the antenna far enough away from the chips so that it doesn't interfere with them."

Joining Kao and Dementyev on the project are their advisers, principal research scientist Chris Schmandt and Joe Paradiso, an MIT associate professor of media arts and sciences.

The team has already met with battery manufacturers in China and says the group is on the trail of technology that could yield a battery that fits onto a thumbnail but is only half a millimeter thick. They are looking at a time frame of about three years for a commercial release, Dementyev told CNET. NailO users would ultimately be able to map gestures to specific actions (left thumbnail swipe = Call Mom, for example).

Nails have gone high-tech before, as in the case of a set of decorative nails that incorporate tiny LED antennas that light up when NFC signals are nearby. We've also seen fake nails with a capacitive tip that can be used just like a smartphone or tablet stylus.

But NailO turns your nail into a trackpad, making you, in essence, part of the computer.

"[You] have the power to take it off, so it still gives you control over it," Kao said. "But it allows this very close connection to your body."