‘Smart Tattoos’ are ‘epidermal electronic systems’ that can be ‘glued’ onto the skin. They can then send signals to devices via touch, and allow its users to interact with the world around them. The technology is looking for its killer application, but it is only matter of time it is widely available before it is found and easily available. The main challenge is to make Smart Tattoos that are safe and robust and last for more than a couple of days.