Lines at the grocery store might become as obsolete as milkmen,
if a new tag that seeks to replace bar codes becomes
commonplace. Researchers from Sunchon National University in
Suncheon, South Korea, and Rice University in Houston have built
a radio frequency identification tag that can be printed
directly onto cereal boxes and potato chip bags. The tag uses
ink laced with carbon nanotubes to print electronics on paper or
plastic that could instantly transmit information about a cart
full of groceries. “You could run your cart by a detector and it
tells you instantly what’s in the cart,” says James M. Tour of
Rice University, whose research group invented the ink. “No more
lines, you just walk out with your stuff.” RFID tags are already
used widely in passports, library books and gadgets that let
cars fly through tollbooths without cash. But those tags are
made from silicon, which is more expensive than paper and has to
be stuck onto the product as a second step. “It’s potentially
much cheaper, printing it a