Cheap chips herald future of wave and pay

00:01 10 August 2012

RFID

Douglas Heaven, reporter

(Image: Josep Lago/AFP/Getty Images)

Small, cheap smart-tag devices that are printed as digital circuits in rolls like newspapers could help kickstart the wireless payment industry. The devices, known as rectennas, combine a rectifier - which converts current from AC to DC - with an antenna, and can harness power directly from radio waves given off by a mobile phone.

Developed by a team at Sunchon National University and Paru Printed Electronics Research Institute in South Korea, the rectenna is based on Near Frequency Communication (NFC) technology, an update to the more familiar RFID standard found in London Underground's Oyster ticketing system, for example.

NFC chips can be used to tag many of the same things RFID chips can, from pets to luggage to boxes in a warehouse. The killer app is likely to be contactless payment, where payments are made by waving a reader in a phone over an NFC price tag. Though this technology has been touted for a few years now - and worldwide payments by NFC-enabled phones are predicted toreach $50 billion - its uptake has been slow, largely due to the costs of installing millions of devices. The new rectennas would bring the cost down to as little as 1 penny per unit, the team says.

But the key advantage of NFC is that it allows two-way communication. An RFID tag can only be read, but with NFC devices information can be sent back and forth between tag and reader.

The back-and-forth exchange of information between a reader and a cheap printed tag would also make peer-to-peer or local Bluetooth-like communication possible. "The application of NFC technology with the smartphone will be limitless in the near future," says Gyoujin Cho of Sunchon National University.

Journal reference: Nanotechnology, DOI: 10.1088/0957-4484/23

2DAYS THOUGHT

Self-cooling crystal makes room-temperature maser

Trading rubies for artificial look-a-likes might seem like a bad idea. But that could be what finally turns masers into valuable technology, ranging in application from medical imaging to chemical sensors.

First dreamed up in the 1950s, the maser is a precursor to the now ubiquitouslaser that emits concentrated microwave radiation instead of visible light.

Although masers have been shown to amplify signals with little background noise, conventional solid-state masers work only under extreme conditions, such as in a vacuum or at temperatures near absolute zero. Masers also need strong magnetic fields to function.

Cryogenically cooled ruby masers have been used in antennas to boost the microwave signals from deep space missions such as NASA's Voyager probes. But for the most part, lasers have outpaced their predecessors here on Earth.

Now, using a pink crystal grown from hydrocarbons – p-terphenyl doped with pentacene – Mark Oxborrow of the UK's National Physical Laboratory and colleagues have created the first maser that works in air at room temperature and with no added magnetic field.

Inner beauty

Oxborrow and his team exploited a phenomenon called inter-system crossing, found to occur in pentacene, which produces a very cold system even while at room temperature. This allows the maser to work as though it's operating within thousandths of a degree of absolute zero.

The truly remarkable thing about this "internal refrigerator" is that with it, the maser's microwave emission is even greater at room temperatures than one under cryogenic conditions, says Oxborrow.

Aharon Blank, an associate professor at the Israel Institute of Technology, came close to making room-temperature masers 10 years ago. Although enthusiastic about Oxborrow's work, he points out that the new maser can only operate for pulses of about 300 microseconds.

"One needs to have continuous operation for most applications, so this very important aspect is still missing," says Blank.

Oxborrow concedes the limitations of his research, but he's confident that renewed interest in masers could lead to significant advances.

"Through modest investment there is scope for substantial improvements," he says.

Journal reference: Nature, DOI: 10.1038/nature11339