Apple’s new watch is supposed to be its most personal device to date. It can measure your heart rate and lets you share it with others. But it seems it may not be quite as personal if you have tattoos on your forearms or darker skin.
In a post that first appeared on Reddit on April 28, a few early-adopter Apple Watch owners complained that they seemed to be having issues receiving notifications on their watches. These watch wearers had tattoos covering the area where a watch would sit on their wrists.
The Apple Watch will lock and require a passcode to use when it doesn’t detect skin contact and tattoos may be fooling the watches into thinking there’s no skin contact when there is. Some in the Reddit thread suggested the issue is a result of the sensor technology that Apple is using to check for skin contact and measure heart rates.
Steven LeBoeuf, a mechanical engineer and the co-founder of Valencell, a company that supplies heart monitor sensors to wearable companies such as Jabra and Scosche, tells Quartz that Reddit’s theory is correct. Apple, like many wearable manufacturers, uses sensors that beam green light toward the skin. It penetrates through the first few layers of skin and measures the rate of bloodflow in the capillaries sitting below the surface. Green light, however, is absorbed by the ink used in most tattoos.
“Green light is a problem for anything dark, especially for tattoos,” LeBoeuf says.
While those with tattooed wrists may experience some issues, there’s also the possibility that the watch will not work as intended for a much larger group of potential watch buyers: those with darker skin. LeBoebuf says that green light is more likely to be absorbed by the skin of people with higher melanin content. Even if the sensors work when a person is sitting down, the darker their skin is, the less likely the sensors are to capture data when the person is moving. “The signal to noise ratio will be much higher,” LeBoeuf says.
SOURCE: Mike Murphy