Tattoos could throw off Apple Watch's sensors

Some of the Apple Watch's features appear to be stymied by a simple wrist tattoo. Whether you have single dainty wrist tattoo or a full sleeve, you might have to switch wrists to get proper utility out of Apple Watch. If both of your wrists are tattooed you might be out of luck when it comes to getting full functionality out of Apple Watch. Reports are coming in about tattoo-caused sensor issues ranging from the inability to track heart rate and distance to being unable to unlock Apple Watch at all.

When worn over a tattoo, Apple Watch has trouble identifying that it's on a wrist, which could spell trouble as it asks for a passcode whenever it leaves the wrist.

According to iMore,

Dark, solid colors seem to give the sensor the most trouble — our tests on solid black and red initially produced heart rate misreadings of up to 196 BPM before failing to read skin contact entirely.

It makes sense that the sensors would have difficulties measuring heart rate through a tattoo considering Apple Watch uses perfusion to measure heart rate. Sensors on the back of the watch measure how much green light is absorbed by the red blood under your skin, and that amount varies with heartbeat.

According to the YouTube video maker, Michael Lovell, Apple Support's response was that the sensors were losing contact with the skin, and that he could replace the watch. But, Apple also warns, "For a small percentage of users, various factors may make it impossible to get any heart rate reading at all." After these latest reports, we're assuming that tattoos are one of the "various factors."

The issue isn't only found on Apple Watch. Fitness trackers like Microsoft Band and Fitbit Charge HF use the same susceptible technology. Although there are workarounds like using a Bluetooth chest strap to measure heart rate, it still doesn't fix the issue of Apple Watch's inability to recognize that it's being worn when placed over a tattoo.