Sensoryx x Murata 6DoF Smart Rings
Unlocking the next generation of AR glasses
Smart glasses on the rise (but not there yet)
Smart AI glasses and AR devices are touted as the next evolution in personal tech, potentially even replacing our smartphones one day. Meta’s Ray-Ban had tremendous success and major players like Google in the US or Xiaomi in China are investing heavily in augmented reality eyewear.
Input and interaction are a key element in making smart glasses mainstream. Unlike smartphones (which have touchscreens) or VR headsets (which often have handheld controllers), AR glasses need a convenient way for users to click, scroll, type, and generally control the interface while on the go. Voice commands are useful but not always practical in public. Eye-tracking and gesture recognition can work, but they require complex built-in sensors and are power-hungry. The bottom line: the vision of replacing our phones with glasses is not reality yet; partially because we haven’t yet nailed an easy, all-purpose way to interact with them.
The search for an AR input solution
To bridge this gap, the tech industry has been exploring various input devices for smart glasses. Hand-held clickers or trackpads were an early stopgap – for example, some smart glasses come with a ring-shaped remote or use the phone as a touch controller. More advanced approaches use hand tracking with onboard cameras, as seen in Microsoft HoloLens or Apple’s Vision Pro, allowing users to pinch or swipe in the air. These can feel natural for basic tasks, but they also demand heavy processing and can suffer in less-than-ideal lighting or when your hands move out of the camera’s view. Meanwhile, voice control is great for simple queries but not ideal for silent or complex inputs. Text input remains an unsolved challenge. Without a physical keyboard or reliable AR keyboard, typing anything longer than a quick reply is cumbersome on current devices.
This has led to growing interest in wearable input devices that are small, intuitive, and always available to the user. Wristbands with neural or EMG sensors (like Meta’s prototype) and smart rings are two promising categories. The basic idea is to let users control AR interfaces with subtle finger movements or gestures, using a device they’re already wearing rather than holding. Among these, smart rings have gained significant traction recently, because they are minimally intrusive – essentially a high-tech extension of your finger.
Smart rings emerge: the competitive landscape
In 2024 and 2025, we’ve seen a wave of smart ring developments aimed at enhancing AR and wearable experiences such as the KiWear smart ring or the Goertek reference design.
The market momentum is clearly building – global smart glasses shipments have surged over 200% recently and are projected to maintain a 60%+ annual growth for the rest of the decade. As this ecosystem grows, input solutions like smart rings are becoming a hot area of development.
However, there’s an important distinction: all these rings (KiWear, Goertek’s, etc.) act as indirect controllers. They rely on 3DOF sensors on the ring itself to detect taps, tilts, or gestures, which are then interpreted as commands. What they don’t generally do is precisely track the 3D position of your hand in space relative to your glasses. In other words, they’re not offering true spatial (6DoF) tracking – they’re more about “discrete input” (like buttons and swipes, just on your finger) than about using your finger as a fully position-tracked pointer. For many AR tasks, discrete gestures are fine. But for the most immersive and powerful interactions, you would want a ring that knows exactly where your hand is, not just what motion it made. This is where a 6DoF smart ring comes in – and it’s the approach that Murata and Sensoryx are taking making this new accessory actually spatial.
What is a “6DoF” ring and why does it matter?
Achieving 6DoF in a finger-worn ring is very challenging. Traditional methods either require external cameras tracking the device or bulky sensors that don’t fit a ring form factor.
Smart rings today are not 6DoF. A ring with just an IMU, for example, can sense some rotation and motion, but it has no fixed reference point – it drifts and cannot tell absolute position (this is an example of inertial tracking limitations: great for detecting relative motion, but prone to drift without external reference). Achieving true 6DoF tracking in a small, battery-powered ring meant for everyday wear calls for a radically different approach. This is where Sensoryx technology enters the scene powered by Murata’s pMUT ultrasonic transducer.
Ultrasonic position tracking – How it works
This solution, developed in partnership with Sensoryx, uses ultrasonic tracking (combined with intelligent sensor fusion) to get precise 6DoF data from a ring. The concept is elegant: the ring is equipped with one or more tiny ultrasonic transducers – pMUT (basically miniature speakers that emit ultrasound: sound waves above the range of human hearing).
One big advantage is that if the AR device lacks a camera, it can still perform 6DoF tracking using just sound. In any case, it is recommended to avoid using the camera as much as possible to save the battery for all-day AR glasses and wearables, every milliwatt counts. Using sound instead of vision can save a lot of energy.
Sensoryx’s tech is flexible: a host device needs either a camera + 1 mic, or 3+ microphones with no camera, to get 6DoF tracking to work. Many smart glasses designs could accommodate a 3-mic array easily (for instance, two in the temple arms and one in the bridge of the glasses). In fact, as the Murata/Sensoryx team demonstrated, “existing microphones can receive low-frequency ultrasound, meaning there is no need for additional receiver hardware” in the device. The glasses’ normal audio microphones double as ultrasound sensors. This is a huge win for design minimalism: we don’t need to strap additional cameras or IR sensors on the glasses to track the ring – a few tiny emitters on the ring and software do the job.
Notably, Murata is at the forefront of developing these tiny ultrasonic emitters. The ring will leverage Murata’s new piezoelectric MEMS ultrasonic transducer (pMUT), an ultra-small ultrasound emitter that is specifically designed for compact, battery-powered devices. The pMUT is highly energy-efficient and can operate at frequencies that off-the-shelf MEMS microphones (commonly used in phones and glasses) can pick up. Despite its small size, it has a wide field of view for sound emission, meaning the ring doesn’t have to be pointed directly at the device – the ultrasound spreads out and can be detected from various angles. Murata’s pMUT essentially enables putting an accurate 3D locator beacon into a ring without sacrificing size or battery life.
How accurate is this ultrasonic 6DoF approach?
In short: very accurate. Ultrasound ranging gives inherently precise distance measurements (on the order of 0.3-1.2 millimeters) which is something cameras struggle with (stereo camera depth error is usually much larger). In fact, the system can achieve “precise accuracy in determining depth and position of objects”, with sub-millimeter precision in ideal conditions. Sensoryx demonstrated that their fusion tracking (ultrasound + optical + inertial) on a reference platform achieved median position errors around 1.5 mm, which is on par with the best VR tracking systems like the HTC Vive. Even using ultrasound alone, the position accuracy remains extremely high – and importantly, stable over time (no drift), since sound travel time doesn’t drift like inertial sensors do. This stability and accuracy mean a user’s virtual hand or pointer can be rendered in the AR scene in the exact spot their real hand is, giving a truly immersive and reliable experience.
Advantages of ultrasound over cameras (and other methods)
Why go through the trouble of ultrasonic tracking? It turns out that ultrasound offers a suite of benefits that make it ideal for wearable AR interfaces:
- Precision in 3D
- Small form factor
- Low power consumption
- Robust in any lighting/noise condition
- Fast response, low latency
- Complete freedom in the mechanical design of the peripheral device.
Taken together, these advantages make a compelling case that ultrasound-based 6DoF rings are a game-changer for AR and spatial computing. It’s not just theory, either… Sensoryx’s technology has been demonstrated in the MALIANG Magic Pencil and other prototypes like our SpatialTag, showing that one can maintain sub-millimeter accuracy even when “with no visual input” (ultrasound-only mode). It also maintains tracking even under difficult conditions like loud ambient noise or bright light by intelligently fusing whatever sensor data is available. In short, this approach brings VR-grade tracking performance to a device the size of a ring, suitable for everyday wear.
More than pointing: enabling text input and beyond
One particularly exciting benefit of a precise 6DoF ring is the possibility of rich, fine-grained input, including text entry, which no simple gesture ring has been able to offer. Today’s ring controllers (like KiWear or Goertek) excel at things like swiping through menus, adjusting volume, or selecting a large button. But ask them to let you type a message or write a sentence, and they fall short. You might get by with voice dictation (as KiWear’s “whisper mic” suggests) or by pulling out your phone. A 6DoF ultrasonic ring, however, opens the door to true text and handwriting input on AR glasses.
Initially, the concept of “Air Writing” allows users to seamlessly write letters, numbers, and symbols in the air. The ring tracks the precise motion of the user’s finger, recognizing handwritten inputs through advanced algorithms. This feature alone represents a significant leap forward compared to existing ring devices, offering a natural and intuitive user experience.
However, the true every day scenario goes beyond air writing. With Murata and Sensoryx’s solution, users can leverage virtually any available surface as an intuitive, on-the-go writing platform. Imagine comfortably sitting at a café and composing messages simply by scribbling with your finger lightly on the tabletop. Alternatively, imagine discreetly jotting notes on your knee during a meeting, or even using your own palm as a quick reference pad while walking. This versatility redefines the concept of mobile input, blending seamlessly into everyday life without interrupting natural social interactions.
In essence, the 6DoF ring can function as both a pointing device and a character input device – something that traditionally required a separate tool. Historically we’ve had one set of devices for pointing (mouse, joystick, touchpad) and another for typing (keyboard). A smart ring with rich motion tracking blurs that line. It can capture continuous motions for pointing/dragging and discrete events for text/commands. This dual capability is critical for AR glasses: you might be pointing at a virtual object one moment and typing a response to a friend the next. A single wearable can cover both jobs. The ultimate goal is to offer users an intuitive input that has basically no learning curve and feels natural while accurate.
Of course, the ring can still do everything the simpler rings do: tapping your thumb and forefinger can be a left-click, rotating your hand can scroll, etc. The difference is that with 6DoF tracking, these interactions can be context aware. For example, if you reach out and tap on an icon hovering in space, the system knows which icon you touched because it has the 3D position. This is more intuitive than, say, using a pre-set gesture like “pinch twice to select the highlighted icon.” It brings AR closer to the familiar “point and click” paradigm that made the desktop GUI so successful, but now in free space.
Toward seamless AR interaction with Murata and Sensoryx
As the AR industry accelerates, with device shipments climbing and new smart glasses models announced each year, it’s clear that interaction technology will play a pivotal role in determining which products succeed. The ultimate goal is to make using smart glasses as effortless and natural as using a smartphone, or even more so. To get there, we need input devices that are unobtrusive, highly accurate, and versatile/intuitive.
The competitive examples from Qualcomm/KiWear, Goertek, and others show a broad recognition that rings and similar wearables are “the future of how we control smart specs”. Each approach has its strengths, but what Murata and Sensoryx bring to the table is a unique combination of hardware innovation and algorithmic capacity. Murata’s miniaturized pMUT ultrasonic transducers and engineering expertise, combined with Sensoryx’s patented 6DoF tracking algorithms, form a synergistic partnership. Together, we are creating a ring that not only matches the functionality of those early competitors but far exceeds it by enabling true spatial interaction (full 6DoF) and rich inputs like text – all while preserving battery life and working in environments where other solutions cannot.
The impact of such a device goes beyond just convenience; it can reshape the AR user experience. Imagine putting on your lightweight AR glasses in the morning, and throughout your day, everything you need (like selecting apps, scrolling through emails, replying to messages, controlling music, and navigating AR overlays) is accomplished by a flick of your finger or a quick scribble in the air. No pulling out a phone, no awkward arm-waving or talking to an AI in public. The technology fades into the background, and you interact with the digital world as seamlessly as the physical one. That is the promise of spatial computing, and unlocking it requires the kind of innovation we’ve outlined here.
In summary, the 6DoF ultrasonic smart ring represents a major step forward in human-computer interaction for AR. It brings the precision of a VR controller, the intuition of a touch interface, and the wearability of a simple ring all into one package. With the first such rings on the horizon, powered by Murata’s components and Sensoryx’s algorithms, we may finally have the key to making smart glasses practical as all-day, stand-alone companions, finally fulfilling the prophecy that one day, AR glasses could replace or at least meaningfully augment the functionalities of our beloved smartphones. The road to that future is being paved now, and we’re excited to be at the forefront of it. Spatial computing is evolving, and with ultrasonic 6DoF rings, the way we interact with our devices might soon evolve beyond the touchscreen. It will evolve to something even more immersive, efficient, and natural!
Want to learn more about sensoryx’s motion tracking technology and innovative spatial tools? Don’t hesitate to reach out to us. We’d love to hear from you and discuss how our technology can enhance your XR experiences!
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