One Ring to Rule VR
Researchers at the University of Tokyo created picoRing, a low-power ring mouse using inductive telemetry to work for weeks on one charge.
For the most part, consumer electronics change pretty rapidly. Look at how the iPhone has changed over the years, for instance. The original release with a big, clunky case, a small display, a low-resolution camera, and modest computing resources has morphed into a streamlined computing platform loaded with high-quality sensors that is more powerful than most laptops. But other technologies defy this trend toward progress. Consider the keyboard and mouse, for instance.
Sure, they may have received some small upgrades, like clickier buttons and new wireless communications protocols, but even so, a keyboard today is more or less the same as one from decades past. This isn’t for a lack of new ideas or technologies to incorporate into them, but because they seem to have reached peak form. The keyboard and mouse are very intuitive to use, and enable rapid data entry, so why mess with success?
But there is always a little room for tweaking. Having to move a hand between the keyboard and mouse, for example, is far from ideal. To address this problem, a group led by researchers at the University of Tokyo has developed what they call picoRing. It is a ring that turns a finger into a computer mouse, so while wearing the device, one is always at hand. And aside from use with traditional computing systems, it can also be used as a transparent way to control virtual reality experiences.
The goal of this project was to build a tiny, ultra-low-power wireless mouse that could run for more than a month on a single charge. The extended battery life was especially important, as this feature has eluded other existing finger mouse designs. Between the tiny batteries that can fit inside a ring and the energy consumed by wireless communication, battery life is typically measured in hours, making these rings impractical for most real world applications.
To overcome this issue, the team devised a novel communication method that consumes just hundreds of microwatts, a fraction of what even Bluetooth Low Energy requires. Instead of relying on conventional wireless links, picoRing uses semi-passive inductive telemetry — a system that transfers data through electromagnetic coupling between a small coil in the ring and another in a wristband.
Inside the 5-gram ring is an eight-turn resonant coil with distributed capacitors. When the wearer scrolls or presses on the small trackball module embedded in the ring, magnets and tactile switches register the motion. A tiny microcontroller interprets these inputs and adjusts the capacitance of the circuit using a voltage-controlled variable capacitor. This changes the ring’s resonant frequency, which the wristband coil detects as a distinct signal.
The wristband, while a bit bulky in prototype form, acts as a relay that bridges the low-power ring to a computer, VR glasses, or other devices. This hybrid setup extends operation to an impressive 600 to 1,000 hours on a single 27 mAh battery — several weeks of regular use.
Beyond pointing and clicking, the picoRing concept could evolve into a multifunctional wearable platform, potentially incorporating sensors for health monitoring, such as heart rate or stress detection. For now, the team sees it as most valuable for AR and VR environments, where traditional mice fall short. The picoRing may not replace the trusty desktop mouse anytime soon, but it sure could come in handy when you need control right at your fingertips.