May/June 2010

Skinput uses arm as keypad

The human body can be used as a sensor.

Chris Harrison, a graduate student at Carnegie Mellon University and a former intern at Microsoft Research, has developed a working prototype of a system called Skinput that turns a person's hand and forearm into a keyboard and screen.



All of these sign-language-like movements, which are customizable, would control a gadget in a person's pocket through a Bluetooth connection.

When fitted with a pico-projector, the Skinput system could display an image of a digital keyboard on a forearm. So, using Skinput, someone could send text messages by tapping his or her arm in certain places without pulling the phone out of a pocket or purse.

"You could pretty much do a lot of what you do on your iPhone," said Harrison, who also stated Skinput "is [like having] your iPhone on your palm."

The system, which has been under development for eight months, won't be commercially available for two to seven years, said Dan Morris, a Microsoft researcher who is working with Harrison on Skinput.

Before that can happen, Skinput's sensors need to get more accurate, he said. In a 13-person trial in Seattle, Wash., Skinput was found to be 96% accurate. But that test only used five buttons. The system would have to improve for people to make use of a full keyboard, which would be the "holy grail," Morris said. "The accuracy is good, but it's not quite consumer-level yet," he said.

The system turns a person's arm and hand into a wiggling, pulsating instrument, full of vibrations that can be picked up and translated.

Skinput users wear an armband that is lined with 10 sensors. These sensors look like tiny diving boards with dumbbells on one end, and they pick up inaudible sounds that range in frequency from 25 to 78 hertz.

When a Skinput user taps a thumb and middle finger together, the impact sends ripples down the skin and through the bones in the arm. Skinput can tell whether a person tapped a middle finger or an index finger, because the two moves sound slightly different to the springy receivers.