nationalmonitorApril 30, 2015 — Early adopters first appeared on Reddit complaining about the issue on April 28. The Apple Watch locks and requires a passcode for use if it doesn’t detect contact with your skin, and new users are finding that tattoos and dark skin might be tricking the watches into believe that there isn’t any skin contact, according to a Quartz report. Valencell, which makes the heart monitor sensors used by companies that make wearables, said in the report that this is correct, and the sensors on its beam a green light onto the skin that penetrates the first layers of skin and measures bloodflow. However, the ink of tattoos often absorbs this green light. Read More