Tiny 'tags' are telling stories

What if your gym shorts could tell your washing machine exactly how to clean them? Or if your refrigerator could say whether the milk has gone sour?

These are details that an increasingly common technology may reveal someday. Radio Frequency Identification (RFID), or radio tags, don't exist in these forms yet, but they do carry "invisible" information about many things today. And scientists are looking into new and amazing uses for them.

You've probably seen radio tags, though you may not have realized it at the time. The tiny devices are used in ID badges to give the right people access to buildings or rooms. They keep track of library books - even pets.

Loaded with information, the tags are placed on or inside something. An electronic "reader" detects that information from a short distance away. Sometimes the information is passed along to a computer. (Don't be confused by another tracking technology with an odd acronym. A Global Positioning System, or GPS, can also track something. GPS units can "watch" migrating tuna or a prisoner on parole, but it's all done via satellite. RFID units are much less expensive and work mostly over short distances.)

"One of the primary advantages of RFID technology is that it doesn't require line of sight," says Dr. Raj Veeramani, professor of engineering and business at the University of Wisconsin, Madison. The "reader" does not need to see the tag. That's because radio signals can pass through most opaque materials (though metals and liquids are difficult). The tags can be inside something - a badge, a box, even an animal.

Look closely

You may have seen the small white bars stuck on CDs, small electronics, or other expensive items in a store. When you buy the item, the cashier runs the tag over a pad that changes the information stored on the tag. That's so when you leave the store, a scanner "reading" the tag will know that you paid.

Your parents may have a tag in their car that lets them drive right through tollbooths. The booths use RFID technology to receive signals from the tags as drivers pass by. The booth then automatically deducts money from a prepaid account so the driver doesn't have to stop and pay the toll.

Some dogs and cats have radio tags embedded in their backs. If the animal gets lost, workers at an animal shelter can scan the tag, get the animal's ID number, look it up on the computer, and notify the owner.

This pet tag is smaller than a grain of rice. It consists of a microprocessor (a "chip") thinner than a piece of paper, a metal coil that acts as an antenna, and a glass or plastic casing. When a reader activates the tag, the antenna transmits a simple signal. In the case of a pet tag, it is a number in binary code.

Tags like these are called "passive tags" because they have no power source. They react when a reader activates them. An "active tag" can transmit information using its own power source.

Some tags contain information that can't be changed. Other tags let you alter or add information using a scanner.

'Reading' at 80 m.p.h.

Larger tags can hold more information and sometimes have their own power source. They can be read from longer distances. Since 1992, every railroad car in America has been required to carry a battery-powered RFID tag. The tags can be read from several feet away on a train traveling 80 miles per hour. The tags help avoid collisions by tracking the movements of trains. They also help stockyards track shipments of cattle. And manufacturers use the tags to track items in stock.

Every day, engineers and inventors are exploring new uses for RFID. Some day, every item in your grocery store may have a tag that identifies the product and gives information about it.

In the future, you'll be able to walk your shopping cart past a reader, and each item in the cart will be automatically noted and totaled. The price of the groceries will be automatically deducted from your bank account.

A carton of milk might have its expiration date included on its tag. Your refrigerator will have a reader to tell you when it's time to pitch that carton of milk.

Researchers at the Massachusetts Institute of Technology in Cambridge, Mass., are looking at ways to use RFID technology in the kitchen, including something they call "Counter Intelligence."

In this experiment, readers embedded in a kitchen counter identify objects and help you with your recipe. A kitchen computer offers substitutions for missing ingredients, keeps track of the ingredients you use, or guides you through cooking a meal.

"Counter Intelligence will have a pair of elves projected on your counter, apparently tugging at your real bag of flour," predicts Joseph Kaye, author of a white paper on the research.

Soon homes will be constructed with readers built into the walls. The sensors would connect to a computer. The computer could then tell you when your library book is due or which suit goes best with your new tie. The sensors would know because they'd detect and keep track of every tagged item in the house.

Companies have explored the idea of putting RFID tags on clothing. The tags could send cleaning instructions to a "smart" washing machine with sensors.

Tags aren't in all these things yet because of their cost. While some tags cost as little as 30 cents, that's still too much to use them on every bottle of milk or carton of eggs. Inventors also face technical challenges. But as RFID improves and more tags are manufactured, costs will come down.

Will the technology ever be used to "tag" humans? It already has. In Mexico City, more than 160 government workers have had microchips implanted in their arms. The chips allow them access to high-security areas.

In some bicycle, running, and triathlon races, a microchip is placed on a racer's bicycle or around his ankle. When the racer crosses the finish line, a reader records the time.

A tag for everyone?

People have considered other uses for the chips: tagging children in case they get lost, tagging convicts who leave prison for work-release programs, and even tagging everyone to help avoid identity theft. Some convicts under house arrest wear ankle bracelets that track them using GPS, but with RFID technology, a microchip would be permanently implanted under their skin.

But all of these uses raise issues about a person's right to privacy that will have to be resolved in the future.

For now, there are plenty of uses for the tags and lots of possibilities for more. "Exciting times await those of us committed to the pursuit of advancements in RFID," says Dr. Jeremy Landt, founder of Amtech Technology in Dallas. "We have a great many developments to look forward to."

Radio goes from bombs to badges

Radio Frequency Identification (RFID) has its roots in radar, which is really an acronym for Radio Detection and Ranging. In World War II, radar stations located and tracked airplanes by bouncing radio signals off them. By the end of the war in 1945, small radio transmitters (they were about the size of a one-pint milk carton) were being used to make proximity fuses. The fuses were put in torpedoes and artillery shells to explode them when they got near their targets. This made the explosions more effective.

By the 1950s, airplanes carried radio transponders. The transponders detected radar signals and "responded" with their own radio signal, identifying the plane and its location. In the 1960s and '70s, researchers explored ways to make the radio transponders smaller and the readers more efficient.

In the 1980s, "radio tags" (actually miniature radio transponders) appeared in security badges and in other security devices to stop theft. Tagged livestock could now be tracked. Cars were equipped with tags to automatically pay tolls at tollbooths. Such tags were even more popular in Europe than in the United States. In the 1990s, use of radio tags expanded greatly as smaller and cheaper devices were created. Today, various kinds of miniature radio transponders are in everything from pets and CDs to medicine bottles. Can you think of other uses for radio tags?

Source: Association for Automatic Identification and Data Capture Technologies

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