Radio frequency identification (RFID) is a method of remotely storing and retrieving data using devices called RFID tags. An RFID tag is a small object, such as an adhesive sticker, that can be attached to or incorporated into a product. RFID tags contain antennae to enable them to receive and respond to radio-frequency queries from an RFID transceiver.
History of RFID tags
Although some people think that the first known device may have been invented by Leon Theremin as an espionage tool for the Russian Government in 1945, the first real usage of RFID devices predates that. During World War II the United Kingdom used RFID devices to distinguish returning English airplanes from inbound German ones. RADAR was only able to signal the presence of a plane, not the kind of plane it was.
Perhaps the first work exploring RFID is the landmark 1948 paper by Harry Stockman, entitled "Communication by Means of Reflected Power" (Proceedings of the IRE, pp1196-1204, October 1948). Stockman predicted that "...considerable research and development work has to be done before the remaining basic problems in reflected-power communication are solved, and before the field of useful applications is explored." It required thirty years of advances in many different fields before RFID became a reality.
Types of RFID tags
RFID tags can be either active or passive.
Passive RFID tags do not have their own power supply: the minute electrical current induced in the antenna by the incoming radio-frequency scan provides enough power for the tag to send a response. Due to power and cost concerns, the response of a passive RFID tag is necessarily brief, typically just an ID number (GUID). Lack of its own power supply makes the device quite small: commercially available products exist that can be embedded under the skin. As of 2004, the smallest such devices commercially available measured 0.4 mm × 0.4 mm, and thinner than a sheet of paper; such devices are practically invisible. Passive tags have practical read ranges that vary from about 10 mm up to about 5 metres.
Active RFID tags, on the other hand, must have a power source, and may have longer ranges and larger memories than passive tags, as well as the ability to store additional information sent by the transceiver. At present, the smallest active tags are about the size of a coin. Many active tags have practical ranges of tens of metres, and a battery life of up to several years.
As passive tags are much cheaper to manufacture and do not depend on a battery, the vast majority of RFID tags in existence are of the passive variety. As of 2004 tags cost from US$0.40. The aim is to produce tags for less than US$0.05 to make widespread RFID tagging commercially viable. However, chip manufacturers supply of integrated circuits is not sufficient and demand is too low for prices to come down soon. Analysts from independent research companies like Gartner and Forrester Research agree that a price level of less than $0.10 is only achievable in 6-8 years.
There are four different kinds of tags commonly in use. They are categorized by their radio frequency: Low frequency tags (between 125 to 134 kilohertz), High frequency tags (13.56 megahertz), UHF tags (868 to 956 megahertz), and Microwave tags (2.45 gigahertz). UHF tags cannot be used globally as there aren't any global regulations for its usage.
See also for some Transponder devices which deliver a similar function, and contactless chipcards.
The RFID System
An RFID system may consist of several components: tags, tag readers, tag programming stations, circulation readers, sorting equipment, and tag inventory wands. Security can be handled in two ways. Security gates can query the ILS to determine its security status or the tag may contain a security bit which would be turned on and off by circulation or self-check reader stations.
The purpose of an RFID system is to enable data to be transmitted by a portable device, called a tag, which is read by an RFID reader and processed according to the needs of a particular application. The data transmitted by the tag may provide identification or location information, or specifics about the product tagged, such as price, color, date of purchase, etc. The use of RFID in tracking and access applications first appeared during the 1980s. RFID quickly gained attention because of its ability to track moving objects. As the technology is refined, more pervasive - and invasive - uses for RFID tags are in the works.
In a typical RFID system, individual objects are equipped with a small, inexpensive tag which contains a transponder with a digital memory chip that is given a unique electronic product code. The interrogator, an antenna packaged with a transceiver and decoder, emits a signal activating the RFID tag so it can read and write data to it. When an RFID tag passes through the electromagnetic zone, it detects the reader's activation signal. The reader decodes the data encoded in the tag's integrated circuit (silicon chip) and the data is passed to the host computer for processing.
Current usage
Low -frequency RFID tags are commonly used for animal identification, beer keg tracking, and automobile key-and-lock, anti-theft systems. Pets are often embedded with small chips so that they may be returned to their owners if lost. In the United States, two RFID frequencies are used: 125kHz (the original standard) and 134.5kHz, the international standard.
High-frequency RFID tags are used in library book or bookstore tracking, pallet tracking, building access control, airline baggage tracking, and apparel item tracking. High-frequency tags are widely used in identification badges, replacing earlier magnetic stripe cards. These badges need only be held within a certain distance of the reader to authenticate the holder.
UHF RFID tags are commonly used commercially in pallet and container tracking, and truck and trailer tracking in shipping yards.
Microwave RFID tags are used in long range access control for vehicles, an example being General Motors' OnStar system.
Some toll booths, such as California's FasTrak and Illinois' I-Pass system, use RFID tags for electronic toll collection. The tags are read as vehicles pass; the information is used to debit the toll from a prepaid account. The system helps to speed traffic through toll plazas.
Sensors such as seismic sensors may be read using RFID transceivers, greatly simplifying remote data collection.
In January 2003, Michelin announced that it has begun testing RFID transponders embedded into tires. After a testing period that is expected to last 18 months, the manufacturer will offer RFID-enabled tires to car-makers. Their primary purpose is tire-tracking in compliance with the United States Transportation, Recall, Enhancement, Accountability and Documentation Act (TREAD Act).
Cards embedded with RFID chips are widely used as electronic cash, e.g. Octopus Card in Hong Kong and the Netherlands to pay fares in mass transit systems and/or retails.
Starting from the 2004 model year, a "Smart Key" option is available to the Toyota Prius and some Lexus models. The key fob uses an active RFID circuit which allow the car to acknowledge the key's presence within 3 feet of the sensor. The driver can open the doors and start the car while the key remains in a purse or pocket.
In August 2004, the Ohio Department of Rehabilitation and Correction (ODRH) approved a $415,000 contract to trial the tracking technology with Alanco Technologies. Inmates will wear "wristwatch-sized" transmitters that can detect if prisoners have been trying to remove them and send an alert to prison computers. This project is not the first such rollout of tracking chips in US prisons. Facilities in Michigan, California and Illinois already employ the technology.
Implantable RFID "chips", originally designed for animal tagging are being used and contemplated for humans as well. Applied Digital Solutions proposes their chip's "unique under-the-skin format" as a solution to identity fraud, secure building access, computer access, storage of medical records, anti-kidnapping initiatives and a variety of law-enforcement applications. Combined with sensors to monitor body functions, the Digital Angel device could provide monitoring for patients. The Baja Beach Club in Barcelona, Spain uses an implantable Verichip to identify their VIP customers, who in turn use it to pay for drinks. The Mexico City police department has implanted approximately 170 of their police officers with the Verichip, to allow access to police databases and possibly track them in case of kidnapping
Potential uses
RFID tags are often envisioned as a replacement for UPC or EAN bar-codes, having a number of important advantages over the older bar-code technology. RFID codes are long enough that every RFID tag may have a unique code, while current UPC codes are limited to a single code for all instances of a particular product. The uniqueness of RFID tags means that a product may be individually tracked as it moves from location to location, finally ending up in the consumer's hands. This may help companies to combat theft and other forms of product loss. It has also been proposed to use RFID for point-of-sale store checkout to replace the cashier with an automatic system which needs no barcode scanning.
An organization called EPCglobal is working on a proposed international standard for the use of RFID and the Electronic Product Code (EPC) in the identification of any item in the supply chain for companies in any industry, anywhere in the world. The organization's board of governors includes representatives from EAN International, Uniform Code Council, The Gillette Company, Procter & Gamble, Wal-Mart, Hewlett-Packard, Johnson & Johnson, and Auto-ID Labs. Some RFID systems use alternative standards based on the ISO-classification 18000-6.
In July 2004, the Food and Drug Administration issued a ruling that essentially begins a final review process that will determine whether hospitals can use RFID systems to identify patients and/or permit relevant hospital staff to access medical records.
Also, the FDA recently approved the country's first RFID chips that can be implanted in humans. The 134.2kHz RFID chips, from VeriChip Corp., a subsidiary of Applied Digital Solutions Inc., can incorporate personal medical information and could save lives and limit injuries from errors in medical treatments, according to the company. The FDA approval was disclosed during a conference call with investors.
Some in-home uses, such as allowing a refrigerator to track the expiration dates of the food it contains, have also been proposed, but few have moved beyond the prototype stage.
Another proposed application is the use of RFID as intelligent traffic signals on the road
