Long lines at store checkouts could be history if a new
technology created in part at Rice University comes to pass.
Rice researchers, in collaboration with a team led by Gyou-jin
Cho at Sunchon National University in Korea, have come up with an
inexpensive, printable transmitter that can be invisibly embedded
in packaging. It would allow a customer to walk a cart full of
groceries or other goods past a scanner on the way to the car; the
scanner would read all items in the cart at once, total them up and
charge the customer's account while adjusting the store's
inventory.
More advanced versions could collect all the information about
the contents of a store in an instant, letting a retailer know
where every package is at any time.
The technology reported in the March issue of the journal
IEEE Transactions on Electron Devices is based on a
carbon-nanotube-infused ink for ink-jet printers first developed in
the Rice lab of James Tour, the T.T. and W.F. Chao Chair in
Chemistry as well as a professor of mechanical engineering and
materials science and of computer science. The ink is used to make
thin-film transistors, a key element in radio-frequency
identification (RFID) tags that can be printed on paper or
plastic.
"We are going to a society where RFID is a key player," said
Cho, a professor of printed electronics engineering at Sunchon, who
expects the technology to mature in five years. Cho and his team
are developing the electronics as well as the roll-to-roll printing
process that, he said, will bring the cost of printing the tags
down to a penny apiece and make them ubiquitous.
RFID tags are almost everywhere already. The tiny electronic
transmitters are used to identify and track products and farm
animals. They're in passports, library books and devices that let
drivers pass through tollbooths without digging for change.
The technology behind RFID goes back to the 1940s, when
Léon Theremin, inventor of the self-named electronic music
instrument heard in so many '50s science fiction and horror movies,
came up with a spy tool for the Soviet Union that drew power from
and retransmitted radio waves.
RFID itself came into being in the 1970s and has been widely
adopted by the Department of Defense and industry to track shipping
containers as they make their way around the world, among many
other uses.
But RFID tags to date are largely silicon-based. Paper or
plastic tags printed as part of a package would cut costs
dramatically. Cho expects his roll-to-roll technique, which uses a
gravure process rather than ink-jet printers, to replace the bar
codes now festooned on just about everything you can buy.
Cho, Tour and their teams reported in the journal a three-step
process to print one-bit tags, including the antenna, electrodes
and dielectric layers, on plastic foil. Cho's lab is working on
16-bit tags that would hold a more practical amount of information
and be printable on paper as well.
Cho came across Tour's inks while spending a sabbatical at Rice
in 2005. "Professor Tour first recommended we use single-walled
carbon nanotubes for printing thin-film transistors," Cho said.
Tour's lab continues to support the project in an advisory role
and occasionally hosts Cho's students. Tour said Rice owns half of
the patent, still pending, upon which all of the technology is
based. "Gyou-jin has carried the brunt of this, and it's his sole
project," Tour said. "We are advisers and we still send him the raw
materials" -- the single-walled carbon nanotubes produced at
Rice.
Printable RFIDs are practical because they're passive. The tags
power up when hit by radio waves at the right frequency and return
the information they contain. "If there's no power source, there's
no lifetime limit. When they receive the RF signal, they emit,"
Tour said.
There are several hurdles to commercialization. First, the
device must be reduced to the size of a bar code, about a third the
size of the one reported in the paper, Tour said. Second, its range
must increase.
"Right now, the emitter has to be pretty close to the tags, but
it's getting farther all the time," he said. "The practical
distance to have it ring up all the items in your shopping cart is
a meter. But the ultimate would be to signal and get immediate
response back from every item in your store – what's on the
shelves, their dates, everything.
"At 300 meters, you're set – you have real-time
information on every item in a warehouse. If something falls behind
a shelf, you know about it. If a product is about to expire, you
know to move it to the front – or to the bargain bin."
Tour allayed concerns about the fate of nanotubes in packaging.
"The amount of nanotubes in an RFID tag is probably less than a
picogram. That means you can produce one trillion of them from a
gram of nanotubes – a miniscule amount. Our HiPco reactor
produces a gram of nanotubes an hour, and that would be enough to
handle every item in every Walmart.
"In fact, more nanotubes occur naturally in the environment, so
it's not even fair to say the risk is minimal. It's
infinitesimal."
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