For years, RFID (radio frequency identification) systems have been synonymous with retail asset tracking. While that remains true today, RFID tags are being used in a broad range of applications — and not just in retail.

Walmart is probably the best known user of RFID technology for marking assets. In 2003, the mega-retailer ordered its top suppliers to mark their pallets and products with passive RFID tags, to help Walmart better manage its inventory. (Lacking power supplies of their own, passive RFID tags only respond when stimulated with radio waves. Active RFID tags have their own batteries, and can thus broadcast their identities unaided.)

Walmart's decision was expected to make RFID tagging a central retail application. But although some retailers followed Walmart's lead, the trend never really caught on.

"The problem was the price," said Justin Patton, director of the University of Arkansas' RFID Research Center, which has a 20,000-square-foot facility in Fayetteville, Ark., that includes labs configured as offices, department stores, factories and homes.

"With a typical passive RFID tag costing anywhere from 7 to 12 cents, it doesn't always make economic sense for manufacturers and wholesalers across the board to use them--even under pressure from Walmart," Patton added.

Despite this, RFID technology has found a place in retail operations that support the economics of the technology. For instance, RFID tags can help store managers track how many items are on the shelves, how many are in the stock room, and when some need to be moved from the latter to the former.

But that is only the beginning, as RFID also is being leveraged outside of the retail arena.

The fundamental concept of RFID tagging — that specific items can be given unique identities and then the remote-sensing technology will track their physical location as they move from place to place — is at the heart of myriad applications being used today in non-retail sectors.

In London, double-decker buses operated by Stagecoach London are being equipped with RFID-enabled tire-pressure sensors. Specifically, the X InCity tires made by Michelin have EPC Gen 2 passive UHF RFID tags embedded into their sidewalls. Each tag relays data from the tire's embedded wireless pressure sensor. Every time the tire is queried for its air-pressure reading, the data is transmitted by the RFID tag, complete with a unique identifier for every tire checked.

Meanwhile, the new Johns Hopkins University School of Medicine facility in Baltimore, uses RFID tags to track the real-time location of hundreds of nurses and 400 unmanned food carts that are moved using a mechanical towline system, as well as big-ticket items such as pumps and wheelchairs. The RFID system makes it easier for managers to deploy staff, deliver food in a timely manner and reduce theft.

In addition, about 50 gas stations in Italy store fuel in RFID-equipped storage tanks. Made by Wolftank, the tanks are equipped with sensors that detect leaks, and the RFID tags are used to transmit news of the leak to gas-station staff.

RFID even has applications in the sanitation sector, Patton said.

"Over 50 cities and municipalities in the U.S. use RFID tags in residential recycling and trash containers, and reader systems on the trucks that pick them up," he said. "They use this to track participation in trash and recycling programs, and--in some instances--actually issue coupons and credits back to homeowners who recycle, to encourage them to continue to do so in the future."

Clearly, RFID has moved beyond its logistics roots. But the technology is gaining ground in this arena, as well, said Chad Collins, chief marketing officer with Accellos, a maker of supply-chain-execution solutions for small and medium-sized businesses.

"Five years ago, you saw RFID tags on shipping containers," Collins said. "Today, these tags are more likely to be used on the trucks themselves, to help their owners/operators track their locations in real time."

RFID tags also have found their way into public safety. For instance, Falken Secure Networks developed RFID tags to be worn by first responders at incident scenes.

"This technology helps commanders keep an eye on their people at all times," said Jack Falkner, president and CEO of Falken Secure Networks. "And the signals get out. We have done field trials inside the subways and high-rise buildings of Toronto with the [city's] fire service, and the RFID tags work."

These examples use one-way RFID tags, but there also are two-way tags that use near-field communication (NFC) to exchange data back and forth.

The best known NFC apps are the key fobs used by motorists to pay for gas. They just tap their personal NFC-enabled fob on a reader, and the cost of the gas is charged to their credit account.

But such tags offer many more possibilities.

"It's not just payment--NFC RFIDs can be used to convey all kinds of information between people and vendors," Patton said. "Put it this way: Every time you see one of those square QR (quick-response) codes that have to be read using a smartphone camera? If this code was based on an NFC-enabled RFID, you would just tap your smartphone on it and get the info sent to you instantly."

Clearly, RFID tags are coming into their own, as more industries see the advantages of one-way tracking and two-way information exchange. But there are still some limits to the technology that are affecting its evolution.

As Patton noted earlier, the first limit is price. For RFID tagging to be applied, it has to make economic sense. This is why tagging chocolate bars with RFID tags won't happen; at least not at the current price point. The money saved through theft reduction and loss won't be offset by the cost of buying, applying and monitoring the RFID tags.

The second limit is environmental.

"RF waves don't like metal, and they don't like water," Patton said.

As a result, items handled within such RF-suppressive situations are generally not worth fitting with RFID tags, even if their value otherwise would make it worthwhile.

The third constraint affecting RFID tags is scale. For this reason, even if it were economically practical to tag every chocolate bar with an RFID tag, the sheer volume of bars would overwhelm most RFID systems. However, it does make economic sense to tag a truck full of candy with an RFID tag, or even each pallet of chocolate bars.

As the person in charge of the University of Arkansas RFID Research Center, Patton understands the full potential of RFID tagging technology. But even he doesn't prescribe it as a panacea. Instead, Patton sees the value of mixing RFID tags with bar and QR codes, optical scanners, near-field communication and any other technology that can help in tracking assets.

"The goal is not to find a 'one size fits all' solution," Patton said. "The goal is to use the right technologies in each circumstance, at the right price, to achieve the right goals."

But there is no doubt that RFID tagging has come into its own during the past few years — even if it has moved beyond its original retail store roots, Patton said.

"And don't think RFID isn't succeeding in retail, because it is," he said. "We know for a fact that Macy's and other similarly large retailers are making big investments in RFID, just as Walmart did almost 10 years ago."