Fitbit Sense: We acquired the insider scoop from Fitbit on temperature monitoring, ECG and extra

The Fitbit Sense is the corporate’s first main watch replace because the Fitbit Versa in 2018, and it provides quite a lot of new sensors: an ECG much like the Apple Watch and Samsung Galaxy Watch 3, stress sensing by way of an electro dermal exercise pores and skin response sensor, and temperature sensing much like the Oura ring.   

I have not examined the Fitbit Sense but as a result of the Fitbit Sense I used to be despatched is not set as much as pair with Fitbit’s app but, however I am holding the $329 (£300, AU$500) watch in my fingers. Whereas I am unable to say how all these sensors will work in on a regular basis use, I can say the watch’s construct has some enhancements over the earlier Fitbit Versas. The curved watch form is an analogous thickness to the $199 Versa 2, however has extra metallic and glass within the end.  

The facet button for beginning exercises and calling up Amazon Alexa (or now, Google Assistant) has been changed with an indented contact space that vibrates when pressed, just like the Fitbit Cost 3 and 4 have (will this be higher when one is sweaty? I do not know). There is a speaker now, for voice assistant and telephone calls. The Sense wrist straps detach much more simply than the Versa’s ever did (which additionally means: new customized watch straps). The charger can be new, a magnetic snap-on that is extra much like what the Apple Watch has and is meant to totally cost in about 15 minutes. It is higher than the alligator-clip-charger Fitbit Versa had earlier than.

There are different overdue additions too, like GPS, a redesigned optical heart-rate sensor that guarantees higher accuracy when operating and sleeping, and perhaps richer knowledge assortment for future well being analysis (optical coronary heart price is already the place blood oxygen, coronary heart price, respiration are drawn from; Samsung’s already exploring blood stress prospects, too). Fitbit’s latest software program updates add particular SpO2 blood oxygen readings to Fitbit watches, and a each day “stress readiness” rating that can add measurements like respiratory price to the combo, that are additionally a part of a brand new step-down mannequin being launched Tuesday, too, the $230 Fitbit Versa 3. 

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However the Sense’s bold triple-add of recent sensors factors in direction of Fitbit’s striving for brand new knowledge to investigate and add to a rising machine-learning well being image, which makes this appear to be Fitbit’s closest try and a health-and-wellness super-wearable. I would welcome the concept of one thing on my wrist that may assist me perceive how I am doing each day, even past how a lot I am strolling round and exercising.

I’ve seen concepts round a well being super-wearable come and go over years. Will Fitbit Sense be that gadget? Since I have not reviewed it but, the reply for now could be a powerful perhaps. And Fitbit seems to be to be leaning on its premium subscription well being service, launched final 12 months, greater than ever to take advantage of Sense’s knowledge (extra particulars on that under).

There are a couple of causes to attend and see. New sensors on wearables are all the time a little bit of an unknown. Possibly Fitbit is breaking by to a complete new territory right here. Or, perhaps not. I keep in mind different wearables’ promising new sensor tech earlier than (the Jawbone Up 3 had bio-impedance; the Microsoft Band 2 had UV sensing, after which there was the sensor-studded research-focused Samsung SimBand), and a few of these by no means did something to dwell as much as their ideas. Will EDA make as a lot of a distinction on a watch as Fitbit guarantees? I am extraordinarily curious to search out out. Temperature sensing remains to be fairly distinctive. ECG is turning into a standard normal on health watches.

However how will these all interconnect? For that, I talked with Fitbit’s Shelten Yuen, head of analysis, and lead analysis scientist Conor Heneghan about what these sensors are aiming to do.


The Fitbit Sense’s temperature sensing will occur nightly and present relative adjustments over time as an alternative of a particular studying.

Richard Peterson/CNET

Temperature: Not like a thermometer, however a nightly relative baseline 

Temperature on wearables began getting a variety of consideration after the coronavirus pandemic shut down the world this 12 months. The potential of detecting signs of sickness by a watch or ring with temperature scanning, or pulse oxygen readings, started to really feel like a promise of wellness forecasting. 

“The origin of this was prepandemic,” Fitbit’s Yuen tolds me over a Zoom name. “Some time in the past, we had this speculation that with a wearable gadget, the temperature sensor could possibly be used to detect a fever and even predict a fever was going to happen.”

The $300 Oura ring has change into essentially the most acknowledged temperature wearable, however there aren’t many others. The Fitbit Sense appears to work in an analogous approach, amassing pores and skin temperature whereas sleeping and delivering outcomes the following morning to point out relative change.

It would not do an prompt temperature scan, and it will not give particular normal physique temperatures to point out in the event you’re 98.6 or 100.3, as an example. However it would present relative temperature adjustments each day. That is as a result of pores and skin temperature readings on a wrist are totally different. I have not examined the Sense but, however I wore an Oura ring for months to examine my temperature, and it was largely a graph of gently fluctuating relative scores. (I wasn’t sick throughout that point, so it is laborious to evaluate.) The temperature consciousness is extra like yet another knowledge level in a set of factors that Fitbit’s utilizing for its each day stress rating calculations.

What’s actually wild is Fitbit acknowledging that current Versa watches have already got a temperature sensor that’s used for gadget battery administration. These sensors helped the  firm put together for what the Sense might do. “We have now some knowledge from that to direct the place this might go sooner or later,” Heneghan says.

These different temperature sensors will not be as skin-focused because the Sense’s temperature sensor, and is probably not as correct. Nevertheless it might assist flip a bunch of Fitbit Versa units into temperature-aware wearables, including a variety of units into the combo quick for potential Fitbit analysis. It sounds just like the Sense’s temperature sensor is extra fine-tuned for the job.


The Sense’s rear sensors and metallic rim on the face measure temperature, ECG, and galvanic pores and skin response for stress measurements.


Stress sensing occurs in a complete new app

The Sense’s electrodermal exercise, or EDA, sensor makes use of the metallic outer rim of the Sense to conduct and get a studying when the palm of your hand is pressed in opposition to it. Fitbit has a brand new EDA app that can take a studying over time and sense your general stress. However this will likely be a unique app than the guts rate-based Loosen up app that at present calculates coronary heart price variability and likewise encourages mindfulness. Fitbit’s additionally launching a brand new set of mindfulness and meditation options into its Premium subscription service that particularly makes use of the EDA sensor.

“Your physique’s sympathetic nervous system is sending little alerts to your sweat glands on a regular basis,” Heneghan says of the EDA sensor. “That creates a tiny bit of additional moisture to your pores and skin, and that adjustments the conductivity of your pores and skin.”

The 2-minute stress scan within the app would require you to carry your hand over the watch the entire time, as would any meditation options utilizing EDA.

“You set your hand over the gadget, and principally it’s a very, very small microcurrent that is going by the palm of your hand. And we are able to choose up the person spikes of nerve sympathetic nervous system exercise” provides Heneghan. “Within the EDA scan app, we’ll rely up the variety of spikes we see each 30 seconds and report that again to you.”

ECG, however no background arrhythmia scanning but 

The Sense’s one-lead electrocardiogram sensor, which Fitbit and Apple name ECG, however is identical as what medical doctors name EKG, works by finger-pinching the metallic bezel on the perimeters of the watch face to finish a circuit. It takes a studying that scans for potential atrial fibrillation very similar to the Apple Watch, current Samsung watches or different units such because the Withings Transfer. Like different watch ECG options, the Sense will not detect coronary heart assaults or different circumstances that extra superior ECG readings might choose up. Additionally, the ECG characteristic remains to be ready for FDA clearance, a course of that is anticipated to be completed this 12 months.

And the Fitbit Sense will not constantly scan coronary heart price for indicators of arrhythmia — at the least not but. The Apple Watch already does this, and Fitbit says it is engaged on it. The corporate introduced its larger-scale atrial fibrillation research in Could. 


The redesigned optical coronary heart price sensors on the again measure gentle by totally different areas directly.

Scott Stein/CNET

Extra correct heart-rate readings might open different measurements

It is all the time laborious to solid ahead and count on an excessive amount of of sensor platforms, as a result of it is unclear the place outcomes will land. As an illustration: Fitbit’s lengthy touted sleep apnea detection nonetheless hasn’t arrived, regardless of guarantees for years. “We’re form of participating with the regulatory course of, and the true problem is simply getting sufficient quantity of information to show out what we have already got,” Fitbit’s Heneghan says to me about progress on detecting sleep apnea.

In the meantime, analysis initiatives with the Fitbit Sense’s new sensors might discover wellness forecasting by temperature and SpO2, however no particular plans are in place but with any research. “Sooner or later, we hope to develop a regulated SpO2 characteristic that might assist with sickness detection and could also be an indicator of potential persistent respiratory circumstances, like COPD (persistent obstructive pulmonary illness), or acute sickness like COVID-19,” Fitbit CEO James Park tells me in e mail reply to my questions.

Fitbit’s present COVID-19 symptom detection analysis has been targeted on heart-rate variability, resting coronary heart price and respiration price as metrics, which CTO Eric Friedman says “can detect 50% of COVID-19 instances a day earlier than onset of signs with 70% specificity.” Fitbit will likely be including sleep knowledge, temperature and SpO2 blood oxygen measurements into additional research.

The center-rate studying enhancements in the meanwhile appear to be about serving to accuracy whereas operating and sleeping, to forestall gaps in knowledge. Nevertheless it might nonetheless open up different channels too: Samsung and Valencell are attempting to crack blood-pressure readings by PPG. Fitbit is not that but, however Park says, “With regards to coronary heart circumstances, we proceed to discover further metrics like pulse arrival time – a metric that may sign that your blood vessels are getting stiffer, which could possibly be a sign of coronary heart illness or hypertension.” 

However in terms of different readings pulled from coronary heart price, Yuen provides: “We’re hoping to discover this knowledge set after which perhaps unlock its potential sooner or later. I do not wish to overpromise. However are we taken with issues like this? Completely.”

Fitbit is admittedly leaning on you paying for Premium

A variety of the each day metrics and instruments Fitbit mentioned with me depend on Fitbit’s $9.99-a-month Premium subscription service, which launched final 12 months and now has over 500,000 subscribers. Some measurements like a particular SpO2 measurement will likely be out there by a free watch face and in additional restricted units of readings on the free app, however longer historical past and evaluation comes with the premium service. 

That Premium service is an additional value, and likewise an additional lock-in. Fitbit’s knowledge would not movement into Google Match or Apple Well being like another wearables do, and it means staying in a channel that may really feel limiting, particularly since most individuals have an rising movement of well being knowledge from different sources.

Fitbit features a six-month free trial of Premium with the Sense (and a 12 months with its lower-cost Encourage 2), however ultimately that is going to be an additional price. Google and Apple have no related subscription well being/health service but, however there are many teaching and health apps that do.

Premium would not appear mandatory, however for lots of what the Sense presents, it might be the way in which you’d wish to get essentially the most out of the gadget.


The Fitbit Sense seems to be bold. How will it dovetail with future Google wearable plans?

Richard Peterson/CNET

What does this all imply with Google?

Fitbit’s pending acquisition by Google has been underway since November, and Fitbit’s subscriber base and knowledge archive might change into a launchpad for a brand new technology of Google well being wearables. However the Fitbit Sense has no added hook-ins to Google’s ecosystem, aside from added Google Assistant voice help along with help for Amazon’s Alexa voice assistant. Park would not touch upon Google. “As you already know, the merger is topic to customary closing circumstances, together with regulatory approvals,” he says. “Till the transaction closes, we proceed to function independently and are targeted on persevering with to create thrilling, revolutionary units and companies for our customers.”

The Fitbit Sense is perhaps the final new Fitbit underneath the Fitbit model. Or, perhaps it is the blueprint for a brand new technology of future units. Clearly, these new sensors are the place Fitbit needs to move subsequent. However what we do not know is how a lot Fitbit’s future will appear to be its current as soon as Google enters the image.

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