Consider this wacky scenario: Someday, in addition to clasping a smartwatch around your wrist every morning, you'll adhere a set of electronic stickers to your nails, too.

This is the vision of Cindy Hsin-Liu Kao and Artem Dementyev, two MIT researchers who've developed a miniature trackpad that fits on your thumbnail. They call their invention NailO, and it functions a lot like your laptop’s trackpad or mouse, working as an additional input method for the gadgets in your life.

Kao and Dementyev are both researchers at the MIT Media Lab, where Kao focuses on software and Dementyev on electrical engineering. For this project the two came together to explore what technology might look like as it creeps ever closer to our bodies. Their hypothesis: As hardware becomes smaller, thinner and more flexible, our personal technology will draw more inspiration from the cosmetics world. In other words, the future of wearables might look less like a Rolex and more like the patterned nail decals at Walgreens.

Unlimited Applications

NailO is a bundle of electronics crammed into a tiny package. It uses capacitive sensors—the same sort in smartphone screens—to register gestures. There’s also a battery, microcontroller, and a Bluetooth chip that lets NailO to any Bluetooth-enabled gadget.

MIT

The first NailO prototype recognizes five gestures: swiping left, right, up and down and single press. In a demo, you can see NailO working like a trackpad as a person uses his index finger to scratch a surprisingly accurate square onto the thumb nail. In another example, a woman swipes from right to left to change the color of an LED necklace. You might someday use NailO to control your phone or computer when your hands are full, “like a third hand,” as Kao puts it. But technically, you could program NailO to do whatever you want.

Kao says lately she’s been wearing a NailO on every finger from her index to pinkie, which turns her fingernails into a continuous scroll bar. More intriguing is the idea of mapping specific functions to each finger. Tap your pinkie to switch the song on Spotify and swipe up on your thumb to increase volume. Kao says she’s been thinking about programming each finger to call a specific person. “My ring finger could be the person I’m married to, or someone who I don’t like I can map to my middle finger,” she says with a laugh.

Beyond novelty, the value of NailO lies in pondering more discreet interaction with our gadgets. Unlike voice-controlled commands or pokes at a smartwatch, using NailO is a silent, nearly imperceptible act. Imagine being in a meeting and dashing off an automated “Got your message, will respond later” simply by tapping a finger, or better yet, swiping across your thumb to ignore a call altogether. As a journalist, I’d love dropping a digital maker to note when a source said something interesting. I'm willing to bet many other people could come up with killer applications. “We’re looking at what are the gestures that will make sense,” says Kao. “What are the interactions we can enable when you put technology this close to the human body?”

Becoming Part of the Body

For all the talk about wearable technology, the body remains a relatively untapped canvas for interaction. We’ve seen how skin can be used as an extension of a smartwatch screen or how we might one day implant digital tattoos into our bodies. NailO isn't nearly so cyborgian—it still requires concentrated effort and consent, which isn't a bad thing. As technology gets smaller and more intimate, there's a risk it gets too intimate. “It gets into this ethical question of is the technology controlling me or am I controlling this technology?” Kao says.

A thumb-borne trackpad may not be the input device of the future, but Kao’s view of cosmetics as the new wearables does seem intriguing. After implants, cosmetics are about as close to the human body a material can get. And as Kao points out, the nail is a natural home for tiny electronics; it’s relatively flat and lacks the nerve endings that can make wearable technology uncomfortable.

Realistically, NailO needs to be streamlined even more before it becomes practical, and the team is working to make that happen. For the time being, though, it’s a compelling look at how we might someday use our bodies as canvasses for technology.