Tattoo Tags

Ian M. Banks's novel Surface Detail is set in a future where artificial intelligences run the show, and people routinely back up their consciousnesses in case of accidents. Heroine Lededje Y'breq is given a present: a tattoo. Before dying her previous body had been covered in an elegant fractal tattoo that showed she was a slave. Her new tattoo, a present from the intelligent if sadistic military ship, Falling Outside The Normal Moral Constraints, is different. As she watches it snake across her body she realises it's really a gadget that she can control, changing the pattern or colour at will. That is just the start. Tattoo as gadget: is that fact or fiction?

It's no longer just fiction. Researchers at the University of Kent, John Batchelor and Mohamed Ali Ziai, have created RFID tags on transfer tattoos. (RFID tags are electronic circuits with antenna to communicate often used as security devices in shops, for example) The Kent researchers' tattoo tag consists of conductive ink on a special plastic that can be stuck onto the skin. If the ink conducts electricity then drawn lines actually become wires. You really can draw a circuit!

It's actually not a problem to put ink onto skin (people write on the back of their hands all the time!) the trouble is making it work as a circuit. Firstly, skin flexes so that the ink cracks and breaks the circuit, and secondly, skin itself conducts electricity. That reduces the effectiveness of the tattoos, shrinking the range the tags can communicate. The original versions were made of a special, nickel-based ink painted on using a stencil. The team are now working with chemists at Manchester University to create inkjet inks allowing the tattoos to be created using a normal printer in the future.

What use is an electronic tattoo? RFID tags are most commonly used to track objects, so the tattoos could be used in a similar way. Give your toddler a tattoo and you won't have to worry about them wandering off in the department store. There are more exciting ideas though. They could control medical implants inside the body like pacemakers, for example, or be used as a body-based network, connecting large numbers of devices you wear like your phone and exercise monitor, say.

More futuristically still, they might even be used to alter the visibility of a person to radar as though they were stealth bomber aircraft. Personal stealth technology for military personnel: perhaps that takes us back to the sort of thing Falling Outside The Normal Moral Constraints was thinking about. You will have to read the book to find out.