French startup Circular claims to have created the world’s thinnest and lightest smart ring — as well as the first-ever to use haptic navigation.

The wearable, named the Circular Ring Slim, became available on pre-order today.

Weighing just 2 grams and measuring a mere 2.2 mm in thickness, the device packs big features into a tiny frame.

To analyse the user’s health, the ring assesses seven biometrics and 142 derived markers. These markers are captured by a suite of sensors.

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One is a simple surface temperature sensor. Another is a three-axis accelerometer count, which assesses activity and movement.

Then there are the sensors that apply PPG. It’s a much-needed acronym: PPG stands for photo-plethysmo-graphy — an optical technique that detects blood volume changes.

In the Circular Slim Ring, the PPG combines three different LED light wavelengths — green, red, and infrared — to capture numerous health vitals. These range from heart and respiratory rates to blood oxygen levels.

When night falls, the ring shifts to tracking signs of sleep quality, such as REM cycles and wake times. While the user dreams, the sensors also measure temperature variations. These are combined with other biometrics to probe immune systems and detect symptoms of illness.   

All readings are then transmitted to Kira+, Circular’s AI assistant, which turns the data into insights and advice. 

Circular is bullish about the system’s accuracy.

“The ring is used in many clinics and scientific studies,” Laurent Bsalis, the company’s founder and CEO, told TNW. “From the outset, we’re very focused on data accuracy and, for example, we’ve preferred not to show data that is hard to get, rather than showing fake data — unlike other competitors.”

The Circular Slim smart ring with green light flashing from the inside
Credit: Circular
The Circular Slim smart ring with green light flashing from the inside

To bolster Circular’s attack on the market, the smart ring comes with a six-day battery life and 20 days of onboard memory.

It also promises data collection every two minutes. According to Circular, the system provides 15 times more health data than competitive trackers.

Another selling point is the new haptic navigation. By tapping inputs on the Circular Slim Ring, users can select various functions.

They can also enjoy haptic vibrations, which provide feedback and alerts. These vibrations also drive several features. Among them is a smart alarm clock, which applies the vibes to wake users at an optimal time in their sleep cycles.

Photo of a cyclist wearing the Circular Slim Smart Ring
Credit: Circular
Photo of a cyclist wearing the Circular Slim Smart Ring

The new device enters a growing market for wearables. At present, smartwatches are far more popular than smart rings — but Circular has high hopes of narrowing the gap.

“They are more comfortable to wear 24/7, are more resistant, can have longer batteries, and you can wear a nice watch at the same time,” Bsalis said. “Rings are getting smaller and smaller while offering more and more functionalities. Some of them will specialize in health, others in consumer applications. We know that rings will take up more and more space on the market.”

The Circular Ring is available today for pre-order at a discounted price of $245 (€226). Shipments will be made on December 15. From that date on, the device will cost $275 (€253). Orders can be made at the Circular website.

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