Smiley-Face Tattoo Tells How Tired You Are

If you always thought that tiredness was only linked with sadness and an overall drooping feeling, the new smiley-face tattoo sensors come to prove there are other ways to see it.

It's not about the way it functions or some complicated operations it performs, but it is a simple, brilliant idea instead. The tattoo serves as disguise for a medical sensor meant to detect changes that appear in the PH level of the skin, according to the metabolic activity caused by a higher physical effort.

The main parts of the mechanism are the “eyes,” which act as reference electrodes, and the “ears,” which connect the tattoo to the measurement device, according to The Daily Mail.

The device addresses especially athletic trainers, as an observation tool for the physical condition, although it could also be used in the cosmetics industry, as a skin secretions monitoring system.

Those are serious targets, but come to think of it, how about a little body that, stuck on your arm, would look up and tell you: “Hey, you're tired!” with a cheerful face. I would definitely have it.