The blood oxygen sensor and app in watchOS 7 are the big new fitness features in Series 6 that require hardware not found on any other Apple Watch. During a measurement, the sensor emits a combination of red LED and infrared light onto your skin. Photodiodes then capture the light that is reflected back onto the underside of the watch. This allows the sensor to determine the color of your blood, which can indicate the level of oxygen present. The clock measures regularly in the background (mostly while sleeping). However, you can also trigger it manually and it only takes 1
As with the EKG measurement, measuring blood oxygen only requires a few taps of the finger on the watch screen. However, you must wear the watch in a certain way to get a successful reading. It took about seven tries to play around with the internship before I got it up and running. Dates most often came when the watch was as high up in my arm as my small / medium sports band would allow when it was secured in the third notch. Apple provides guidelines in the Blood Oxygen app that explain proper placement. Among other things, it is recommended not to position the watch too low on the wrist.
While it just got easier for me to take these measurements, I am curious to see how the watch takes automatic measurements while I sleep. It’s pretty easy for wearables to move around on your wrist when you’re wearing them in bed. This can affect the watch’s ability to accurately capture blood oxygen information, if at all.
The new solo loop band could be Apple’s way of addressing this potential problem. This new band is a single piece of buoyant, liquid silicone that extends around your wrist. It comes in nine (yes, nine) sizes, and you can download a printable tool from Apple’s website that will help you determine which is right for you. My solo loop comes in size 3, and while turning it on and off is a little tricky, it’s more comfortable than I thought. Most importantly, the watch should be flush with my skin so that it can measure accurate blood oxygen levels.
Let’s take a step back and talk about overall performance. The Series 6 is definitely faster than the Series 5 and the increased speed is most noticeable when starting apps and when swiping between the watch faces. Apple still doesn’t allow developers to create watch faces from scratch, but they can now customize some Apple-made designs with complications relevant to their apps. I really enjoyed the new, customizable Memoji face because I had a little ghost friend with me all day who floated into the frame whenever I turned up my wrist.