Man holding an iPhone 7
Earbuds could help you take a selfie with just a wink or a smile Reuters

A smart earbud with the ability to read the facial expressions of its wearer has been developed to help disabled smartphone users answers calls with a smile or take photographs with a wink.

The device, which could also help drivers use their phones hands-free, uses an earbud fitted with electrodes which recognise changes in the shape of the ear canal.

More innovation news from IBTimes UK

Facial expressions like smiling, winking, opening the mouth and making a 'shhh' sound all cause the shape of the canal to change; each movement can be mapped to an instruction sent to a connected smartphone or other device.

Called Ear Field Sensing or EarFS for short, the kit works by placing one electrode inside the ear while a second reference electrode is clipped to the lobe. When the user smiles, winks or performs another expression the system recognises, muscles in the ear move; this causes the earbud to alter its shape, producing a change in the electrical field of the inserted electrode compared to the other.

Denys Matthies of the Fraunhofer Institute for Computer Graphics Research in Rostock, Germany, said: "We're not trying to replace current input methods, just complement them." He says the system, which remains an experimental prototype for now, could be used to help disabled people interact with a smartphone more easily.

The system can currently recognise five expressions – smiling, winking, turning of the head, opening of the mouth and saying a 'shhh' sound – with a 90% accuracy.

Matthies added: "It's currently still just a research project, but something as simple as answering a call with a facial expression could be possible soon."

As well as helping disabled users or people whose hands are busy, such a system could help create more socially unobtrusive ways to interact with technology. Speaking to New Scientist, Daniel Ashbrook of the Rochester Institute of Technology in New York said: "It can be rude or inappropriate to look down at your phone and say 'Hey Siri, block that call'...It takes four seconds to get your phone out of your pocket and in a position to do something meaningful, so anything you can do in that time with just an earbud is a big win."