Despite the popularity of smartwatches, these wrist-worn devices still have several limitations with their small touchscreen being one of the most notable annoyances. Cognizant of this, a team from Carnegie Mellon University has developed an innovative way to extend the wearable gadget’s interface by turning your entire forearm into a fully-functional touchpad.
A project out of the Human-Computer Interaction Institute’s Future Interfaces Group, the aptly named SkinTrack allows for continuous touch tracking on both the hands and lower arms. It can even sense touches at discrete locations on the skin, enabling functionality similar to buttons or slider controls.
The wearable system only consists of an electrode-laden wristband attached to the watch and a special ring, which emits a low-energy, high-frequency signal through the skin whenever the finger touches or comes close to the skin’s surface. From there, the sensor simply calculates the distances between itself and the finger with the ring.
According to its creators, “By using electrodes integrated into the watch’s strap, it’s possible to pinpoint the source of those electromagnetic waves because the phase of the waves will vary. Electrodes corresponding to the 12 o’clock and 6 o’clock positions on the watch, for instance, can detect phase differences that can determine the position of the finger along the width of the arm; electrodes at the 3 o’clock and 9 o’clock positions can determine the finger’s position along the length of the arm.”
The team found that they could determine when the finger was touching the skin with 99 percent accuracy, and could resolve the location of the touches with a mean error of 7.6 millimeters. That compares well with other on-body finger-tracking systems and approaches touchscreen-like accuracy.
While the possibilities may be endless, some sample use cases include playing games, scrolling through lists, zooming in and out of onscreen maps, and doodling. Beyond that, a number pad application lets wearers use the back of their hand as a dial pad, where hovering a finger over the hand acts as a cursor, highlighting numbers on the screen to aid in targeting touch points.
2D tracking also enables spatial gestures. Since SkinTrack can recognize hot key commands, you can trace an “N” on your hand to open up your news app, or “S” to silence an incoming call. Are you tired of that tiny display and ready for some more screen real estate? See the prototype in action below, and delve deeper into the project in its paper here.