"It may be true that 10-20 year-olds don't want to wear a watch on their wrist, but you can be sure they'll be far more interested in wearing an electronics tattoo, if only to piss off their parents," – Regina Dugan
Motorola shows off tattoo and swallowable password hardware
https:// www.theregister.co.uk/2013/05/31/motorola_tattoo_pill_authentication/