Wearable electronic tattoos that can sense electrophysiological signals like heart rate and brain activity or monitor hydration and glucose levels from sweat are under development. They can even be used for controlling mobile devices, for example shuffling a music playlist at the touch of a tattoo, or for luminescent body art that lights up the skin.
The professor in the TedTalk above has created and tested a tattoo that uses UV radiation sensors, so it can change colour when your sun lotion needs replacing.
These tattoos are not as permanent as normal tattoos and not as ‘comfartable’, but neither is electronics placed under your skin which are being developed by biohackers.
Some more on this story over at FastCompany