Researchers have created AuraRing, a ring and wristband combination that can detect the precise location of someone’s index finger and continuously track hand movements. The ring emits a signal that can be picked up on the wristband, which can then identify the position and orientation of the ring and the finger it’s attached to. It captures the fine-grain manipulation performed by the fingers — not just a gesture or where the finger is pointed but something that can track the finger completely.
AuraRing is composed of a coil of wire wrapped 800 times around a 3D-printed ring. A current running through the wire generates a magnetic field that is picked up by three sensors on the wristband. Based on what values the sensors detect, the researchers can continuously identify the exact position of the ring in space. From there, they can determine where the user’s finger is located.
To have continuous tracking in other smart rings, all the data must be streamed using wireless communication, which consumes significant power. AuraRing consumes 2.3 milliwatts of power, which produces an oscillating magnetic field that the wristband can constantly sense. In this way, there is no need for any communication from the ring to the wristband.
With continuous tracking, AuraRing can pick up handwriting — potentially for short responses to text messages — or allow someone to have a virtual reality avatar hand that mimics what they’re doing with their actual hand. In addition, because AuraRing uses magnetic fields, it can still track hands even when they are out of sight such as when a user is on a crowded bus and can’t reach their phone. It can also detect taps, flicks, or even a small pinch versus a big pinch; for example, if a user writes “hello,” they could use a flick or a pinch to send that data.
AuraRing was designed to be ready to use as soon as it comes out of the box and not be dependent on a specific user. They tested the system on 12 participants with different hand sizes. The team compared the actual location of a participant’s finger to where AuraRing said it was. Most of the time, the system’s tracked location agreed with the actual location within a few millimeters.
Because AuraRing continuously monitors hand movements and not just gestures, it provides a rich set of inputs applicable to multiple industries. The technology behind AuraRing could be easily added to smart watches and other wristband devices.