Researchers at the MIT Media Laboratory are blurring
the boundary between the physical and digital worlds with
the development of a nail-mounted gestural input surface
According to Cindy Hsin-Liu Kao, an MIT graduate
student and lead author of NailO: Fingernails as an Input
Surface, a paper describing the system, the technology
could allow users to control wireless devices when their
hands are full. “For example, if both your hands are busy
cooking, but you need to navigate a mobile device, NailO
could be used like a third hand,” says Kao.
The researchers drew inspiration from decorative
nail stickers found in the cosmetic industry. “We were
motivated by fashion trends in East Asian countries, where
decorative art stickers are very popular,” explains Kao. “So
instead of having everything on your wrist, we’re making it
more discrete in the form factor of a cosmetic product.”
NailO involves multilayered miniaturized hardware that
wirelessly transmits data via Bluetooth to a mobile device
or PC. The hardware is then mounted on the thumbnail
with cosmetic nail tape.
OPTIMIZED FOR TOUCH
Kao and Artem Dementyev, a fellow graduate student and
the paper’s co-author, began work on their first prototype
in August 2014. After finishing a rigid circuit board design
by the end of September, the two began work on a second
version – a flexible circuit board.
Kao and Dementyev’s project is supported by their
advisors Chris Schmandt, principal research scientist, and
Joe Paradiso, an MIT professor of media arts and science.
The researchers designed NailO to use projected
capacitance to sense finger touch gestures, in which the
capacitance is measured on each electrode independently.
When touched, a capacitor is formed between the finger
and the sensing electrode, and capacitance is sensed
indirectly by charging and discharging a resistor-capacitor
“The electrodes are optimized specifically for touch,”
explains Dementyev. “The capacitive touch doesn’t pick up
anything non-conductive, like your sleeve.”
For the first prototype, the team constructed its sensors
by printing copper electrodes on sheets of flexible
polyester. The process allowed them to experiment with
a range of electrode layouts; however, they are currently
using off-the-shelf sheets of electrodes comparable to
those found in some touchpads.
FOUR UNIQUE LAYERS
NailO is a stacked device, consisting of four unique layers.
The top layer is an interchangeable, decorative nail sticker
for users to customize sensor appearance. “Because the
appearance is so malleable with NailO, you can easily adjust
it to how you want it to look,” explains Kao.
Wearable technology is on the rise, particularly with regard to fitness trackers and health
monitors. However, these wearable
technologies make for somewhat bulky
wristbands, necklaces, or other devices
that hang from the human body.
By Kaylie Duffy, Associate Editor
Shown here is the first NailO prototype with Rigid PCB and copper printed
electrodes. The 4 layers are shown individually, stacked on top of each other.