Since the device debuted on Friday, early adopters with body art have been complaining on Twitter and Reddit about problems with notifications and the heart rate sensor. Apple isn’t commenting on the controversy just yet, but the denizens of the Internet think they have figured it out.
It goes something like this: the heart rate sensor uses green and infrared lights to detect your heartbeat. The light amount of light absorbed changes based on the amount of blood in the wrist, and that change is used to calculate your heart rate. Dark tattoo ink prevents the light from penetrating the skin to read the blood. It’s not a problem for dark skin, because it’s much more translucent than ink.
Now, this doesn’t sound like it would be a major problem for anyone who buys the Apple Watch for everything other than the health features, but it is. The wrist detection feature uses the heart rate sensor to detect if the watch is being worn, or just played with. Some notifications only come through with wrist detection turned on. Turning off wrist detection revives the notifications, but can also impact other features, including phone calls and Apple Pay (which the Wall Street Journal reports is coming to Canada in November).
It seemed obvious Apple would run into some issues with the first generation of the smartwatch, but this could turn out to be a rather big problem considering many of its younger customers are into the tattoo culture.