Don't use an Apple Watch if you have a wrist tattoo

If you shelled out a small fortune to get an Apple Watch, it may be best not to mix and match it with an arm sleeve tattoo, and it's not just because of fashion sense.

 

Apple-oriented site iMore.com said several users have taken to social media to note the Watch's heart rate sensors may not give an accurate reading due to interference from ink pigmentation.

 

"The ink pigmentation interferes with the sensor's ability to read your heart rate — and with it, the Watch's ability to assess whether or not it's maintaining skin contact," it said.

 

Citing results from its own brief tests, it said the interference could be most likely if the tattoo has a "solid, darker color."

 

iMore said it tested the Watch's sensors against tattooed and non-tattooed sections on the wrist and elsewhere on the body.

 

"On non-tattooed non-wrist sections, the sensors gave identical readings as when also tested on the wrist; on tattooed sections, sensor readings varied wildly depending on colors and shading," it said.

 

Also, it said dark, solid colors "seem to give the sensor the most trouble."

 

Tests on solid black and red initially produced heart rate misreadings of up to 196 BPM before failing to read skin contact entirely, it said.

 

While tests on lighter tattoo colors including purple, yellow, and orange produced slightly elevated heart misreads of 80 BPM compared to 69 BPM on the wearer's non-tattooed wrist, they did not appear to interfere with skin contact registration.

 

According to iMore, the Watch measures heart rate via LEDs and photodiodes to detect the amount of blood flowing through a user's wrist.

 

The watch can also use infrared light to measure heart rate every 10 minutes.

 

"(But) anything that reduces that light's reflectiveness — ink pigmentation within your skin, for example — can interfere with that sensor," it said.

 

However, iMore said natural skin pigmentation such as naturally darker skin does not block light in the same way, so should not be a problem for the watch.

 

A separate report on The Verge said this issue could be annoying, as Apple Watch will request a security PIN "almost immediately after it detects it has left an owner's wrist." — Joel Locsin/TJD, GMA News