Review: Wellue O2Ring – keep an eye on your SpO2 with medical grade accuracy

A number of companies are looking beyond the wrist to the next frontier in wearable technology. Few people know that the finger can provide a useful snapshot of a person’s overall health. This is because it contains arteries that can be detected by finger-worn devices to capture physiological data such as your heart rate and blood oxygen.

Slim and sleek, smart rings are attracting a lot of attention. Especially among people who are looking for something useful, light and fashionable. Big brands like Apple, Fitbit and Garmin have yet to enter this arena. But there are a few other players with great deals.

One of them is Wellue. Their FDA-registered O2Ring continuously monitors your blood oxygen (SpO2), heart rate, and movement with clinical-grade accuracy. Slip it over your thumb or index finger and it will do the rest. You can view real-time data on the device itself or sync the ring with the included app or PC/Mac software for detailed analysis and trend reporting.

Usually retails for $169 on getwellue.com (use coupon GW10 for 10% off), the O2Ring is more expensive than a typical fingertip blood oxygen monitor. Is it worth the extra price? I left last week to find out.

Wellue O2Ring review: Design and hardware

• Feels solidly built – rubberized design
• More about function than fashion
• Large, easy-to-read display
• 12-16 days battery life

look and feel

Despite its name, the Wellue O2ring is not a ring in the classic sense. The device is made of soft silicone that has a rubbery feel. It’s also larger than a typical ring, so it’s more about function than style. But it’s smaller and much less bulky than the fingertip blood oxygen monitors it’s supposed to replace.

The actual size of the device is 4 x 3 x 3.5 cm (L x W x H) and weighs 15 grams. It is suitable for fingers measuring between 50 and 82 mm. The rubberized band stretches and can therefore be spent on those with large fingers.

Although it’s not fancy, the whole thing seems solidly built. A large display sits on top which is easy to read thanks to its size.

To one side of the screen is a touch key that you can use to wake up the screen and cycle through time, heart rate, and oxygen level readings. There is no power button. As soon as you put the ring on, the sensor lights up and the screen comes to life. When you remove the ring, it automatically turns off after a few seconds. I really liked this because most of my other devices require powering on and off. The touch key is also very responsive.

You are supposed to wear the O2Ring on your thumb. If that seems too tight, the other option is to use the index finger. I found the group approach to be much more comfortable than the fingertip alternatives as it doesn’t get in the way. You can type and do just about anything you want while wearing the ring.

To test it well, for a week, I wore the Wellue O2Ring every night while I slept. With all the typical throws and flips, he stayed put and never felt in danger of slipping. The device’s rounded corners mean it won’t snag on sheets or pillows. In fact, the ring is so comfortable that I would wake up in the morning forgetting it’s even on.

The only part of the design I’m a bit cautious about is the flexible tip at the end of the silicone band. It looks a little flimsy. I don’t know if it might break at some point with long term use.

Unlike some other smart rings, this device is primarily intended for use at home or in healthcare facilities. The O2Ring’s bulk means it’s something you probably wouldn’t want to wear in outdoor environments anyway. You could if you wanted. But blood oxygen readings are best taken at rest or during sleep, so taking measurements under these conditions would be pointless.

Wellue says the device is designed to give medically accurate readings while you’re sleeping, sitting somewhere, or walking slowly. Some of their customers are professional pilots. They use the O2Ring to monitor their blood oxygen while flying in airplanes.

The device has an IP24 rating for dust and water resistance. So you shouldn’t shower or bathe with it, but you can probably wear it in the rain.

under the hood

The technology used by Wellue O2ring is called transmissive oximetry. This is reliable and used in hospitals and clinics. Smartwatches use reflective technology which is not considered accurate.

With transmissive oximetry, a device passes two wavelengths of light through a thin part of the body to a photodetector. It then measures the changing absorbance at each of the wavelengths. The fingertips are perfect for such measurements because they have higher blood flows than other tissues. Hence the accuracy of the O2Ring and traditional clamp oximeters.

The O2ring has built-in memory that allows it to work independently without a phone. There are 4 small memory cards built in. Each can store approximately 10 hours of data.

This means you need to sync with the app from time to time. So if you track your sleep every night, after four or five nights, you’ll need to launch the app. If you don’t, the oldest recording will be deleted when the memory is full. A synchronization is done automatically when connected via Blueooth 4.0 to the smartphone application or computer software.

Other than accuracy, what sets the O2Ring apart from other devices of its type is the sampling rate. Oxygen levels, pulse rate and movement data are captured at 1 second intervals. For those with medical conditions such as sleep apnea, the high sample rate will be very important.

Battery life

As for the all-important battery life, the Oxygen Ring has an advertised run time of between 12 and 16 hours on a single charge. Wellue says that’s enough for two nights. In practice, however, I found it best to charge it after a full night’s sleep. I tend to sleep at least 8 hours a night and that certainly wouldn’t last me two full nights.

Charging is done via a micro-USB cord. Unfortunately, there’s no progress bar or percentage loaded on the screen, so you’ll have to leave it on until the screen turns off. It can take over an hour to go from zero to full, so it’s not that fast.

The battery inside the Wellue O2Ring is similar to a button cell for watches. So theoretically, you could replace it yourself if needed, or have a repairman do it. But the battery should last a few years, so that probably wouldn’t be necessary.

Wellue O2Ring review: Functionality

• Clinical grade data, registered with the FDA for accuracy
• Choice of smartphone app or PC/Mac software
• Abnormal SpO2 and heart rate alerts
• Export high resolution oximetry reports to share with doctor

Installation and first use

One of the best things about this product for me is that it’s incredibly easy to install and just as easy to use. Start by downloading the ViHealth app on your iPhone or Android device. Open it and create an account.

Slide your finger into O2Ring (or plug it into the charger) to turn it on and the app will find it and ask you if you want to pair. Click on the image of the ring and you’re done. From then on, it will automatically connect whenever the ring is turned on and the app is opened. You can also use the app in offline mode to view data when the ringer is off.

At this point, you might want to change a few options. Go to the “Settings” tab of the app where you will have the option to connect to Apple Health and where you can activate the heart rate and oxygen alarms. This will also allow you to configure the high and low thresholds for each.

The O2Ring vibrates to alert the wearer if they have approached predefined limits. The idea is that it will alert you to heart abnormalities or hypoxic events so you can take a break to recover. So, for example, if your oxygen level drops below the configured threshold during sleep, the vibration will wake you up so you can adjust your sleep position.

For those who suffer from sleep apnea, this is a feature that cheap oxygen monitors simply don’t have. So this feature alone justifies the higher price of the Wellue O2Ring compared to such devices.

The discreet vibration also helps your partner sleep better. Think of it as a vibrant smartphone. Something like this is ideal for meetings and noisy environments. Attention, there is no built-in loudspeaker in the ring. However, the mobile app can trigger audio alarms if that’s your preference. You can even use both at the same time, the vibration alarm on the ringtone and the sound alarm on the phone.

However, I think there is a missed opportunity that could be fixed with a firmware update. Since the vibration functionality is already there along with a clock, it would be nice if the O2Ring could act as a morning wake-up alarm.

Lots of informative data in the smartphone app

You can use the ring itself for real-time blood oxygen and heart rate readings. Once you put the device on, it will automatically start capturing measurements for about a minute before turning off the screen so you can sleep. Simple death. Real-time data can also be viewed in the app’s dashboard.

I found the Perfusion Index (PI) to be a nice feature. Similar to a cell phone signal strength indication, it quantifies the quality of the pulse reading. This may vary depending on many factors such as how you wear the ring, physiological conditions, skin temperature, etc. You can use it to assess whether you are wearing the device correctly. As long as PI is green, you’re good to go.

In the morning, you remove the ring, the screen lights up briefly and starts a countdown from 10 to 0 then a message “SAVING” and “END”. After that, you can turn on your phone, open the app, and allow it to sync.

Blood oxygen measurements seem to be accurate compared to a traditional oximeter. This is to be expected given that Wellue has obtained FDA approval for the device. Additionally, metrics are captured every second and displayed at four-second intervals in the app. Much more useful than Apple Health which only shows SpO2 data in 10 minute intervals.

The app’s “History” tab shows you a timeline of all your metrics. What I didn’t like was that every time you take the ring off it saves the session as a separate session. So if you take the ring off in the middle of the night and put it back on, two sets of data will be created. So in that sense, it can get a bit messy.

Each individual session shows a wealth of data. There’s a handy O2 score bar that quantifies your lack of oxygen during sleep. It combines the frequency, duration and depth of oxygen drops. In my case, I was usually at 9.8 and 9.9, which is considered excellent. If the score turns yellow or red, Wellue suggests you seek advice from your doctor. To make it easier for you, the O2Ring can create a PDF SpO2 report that you can email to your doctor.

Other data shows your average pulse for the session, average SpO2, number of drops above 4%, lowest SpO2 and more. All very useful stuff that goes into more detail as far as blood oxygen than any other device I’ve come across. Nothing really there that lets you create high-resolution oximetry reports at four-second intervals that can be shared with a click.

There is also a PC, MAC application that you can optionally use

I also liked that you have the option to install PC or Mac software called O2 Insight Pro. Just download it from Wellue website.

It works exactly the same way as the smartphone app but everything is displayed on the large screen in an easier to read format. You’ll have no trouble dissecting hourly charts in detail – it’s comparable to an actual sleep study report.

Wellue O2Ring review: In the end, is it worth it?

The Wellue O2Ring is a very useful product. But it’s not for everyone. The device is primarily designed for people who need to track their oxygen levels in detail, especially those who have or suspect they have sleep apnea or another medical condition. If you’ve recently tested positive for Covid-19, this ring could give you peace of mind.

The device mainly does one thing and it does it well – it tracks your blood oxygen at one-second intervals with medical-grade precision. Other stats you will get are heart rate and body movement. The Thing will also alert you if you experience low oxygen levels or irregular heartbeats. For those who suffer from sleep disorders, this could be a lifesaver. Change position and the buzzing will stop.

The ring is quite large, so it’s not something you would want to wear around the clock. But for measurements at home, in the office or during the night, it’s very useful. The device is also well made and comfortable to wear, in my case on my thumb.

Wellue O2 ring Use coupon GW10 for 10% off

Usually retails for $169 on getwellue.com (use coupon GW10 for 10% off), the O2Ring is expensive if you only need ad hoc readings of blood oxygen and heart rate. A typical fingertip pulse oximeter is a much cheaper option. But if you need nighttime monitoring with alarms and long-term tracking, this is probably the best option. For some, it could become their most important piece of jewelry.