NailO functions a lot like a laptop’s trackpad or mouse, working as an additional input method for the gadgets in your life. It involves multilayered miniaturized hardware that wirelessly transmits data via Bluetooth to a mobile device or PC. 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 can be topped with nail art to make it less odd-looking. The NailO prototype recognizes five gestures: swiping left, right, up and down and single press. The technology could let users control wireless devices when their hands are full. It could also augment other interfaces, e.g., allowing someone texting on a cellphone to toggle between symbol sets without interrupting typing. It could also enable subtle communication, such as sending a quick text while attending a meeting.