MIT researchers have developed a wireless touchpad small enough to fit on your fingernail. Dubbed NailO, the prototype is modeled after cosmetic nail stickers. It squeezes a capacitive sensor, microcontroller, Bluetooth radio, and battery into a footprint no larger than a quarter. The idea is to provide an alternative input mechanism for wearables and situations that don't map well to conventional control schemes.
Here's a preview of the NailO in action:
Although the NailO seems a little gimmicky, the design is backed by sound rationales. Thumbnails provide a firm surface that should aid consistent tracking, for example. They're easy to swipe with any finger, too—even when you're holding something in your hand.
The people behind the project are working with suppliers on a super-slim battery that's only 0.5 mm thick. That power source won't provide a lot of juice, necessitating an unlock mechanism that should also prevent inadvertent contact from triggering unwanted actions.
There's no indication of how close the NailO might be to becoming an actual product. The concept is promising, though, and I'm curious to see how others tackle the input challenges associated with wearable devices.