​Fitbit smart ring patent reveals medical grade SpO2 and blood pressure tracking

New sensor tech means better accuracy
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Fitbit has dropped a patent for a medical grade smart ring, in what could be a dramatic new form factor for the Google-owned company.

A filing at the US Patent and Trademark Office (spotted by TechRadar) reveals a heart rate sensing smart ring, with a host of biometric features.

The filing dates back to Dec 2020 but was only published in June 2021.

The patent reveals plans for SpO2 tracking and NFC – which means it could retain many of Fitbit’s top features, including Fitbit Pay.

But it’s not any old SpO2 monitor. The patent talks about a photodetector sensor that enables transmissive examination of blood oxygen levels, which is more accurate than the type of SpO2 sensor found on wrist wearables that uses reflected light.

Transmissive detection means shining a light through your finger to receptors on the other side – which is how medical grade sensors work.

The patent says that reflected light sensors suffer from noise problems, especially if the watch isn’t fully flush to the user’s skin.

And the wording indicates that Fitbit believes that transmissive detection could be the key to tracking future data points, such as cuffless blood pressure and even glucose levels.

The patent states that: “Systems can utilize the ring to monitor the oxygen saturation, pulse, blood pressure, glucose levels and lipd concentration” of the wearer.

​Fitbit smart ring patent reveals medical grade SpO2 and blood pressure tracking

Source: USPATO

The idea of a smart ring might sound far-fetched, but it’s an established form-factor that’s enjoyed niche success.

The Oura Ring is the biggest player to date, which specializes in sleep and wellness tracking – and was involved in trials around its suitability for tracking COVID 19.

However, two of the big players – the Motiv Ring and Amazon Echo Loop – have been discontinued. Motiv was bought out and has pivoted to biometric security, and Amazon didn’t advance the Loop past its Day 1 Editions program.

But while Motiv and Oura impressed us in our reviews, a chunky smart ring is arguably more noticeable than a fitness tracker on the wrist.

And that’s perhaps why putting the features of a Fitbit into a smart ring isn’t technically difficult, there are warnings that users and consumers may not be as interested in the form factor.

However, Fitbit may be preparing these sensors for a medical play – and using transmissive detection could be the key to securing FDA approvals.

Of course, filing a patent doesn’t mean we’ll ever see the product on sale. Companies like Apple, Google and Fitbit file scores of patents that never see a proper release. But this is an interesting example of where Fitbit sees the future of its technology.


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James Stables


James is the co-founder of Wareable, and he has been a technology journalist for 15 years.

He started his career at Future Publishing, James became the features editor of T3 Magazine and T3.com and was a regular contributor to TechRadar – before leaving Future Publishing to found Wareable in 2014.

James has been at the helm of Wareable since 2014 and has become one of the leading experts in wearable technologies globally. He has reviewed, tested, and covered pretty much every wearable on the market, and is passionate about the evolving industry, and wearables helping people achieve healthier and happier lives.

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