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.
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.
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.
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