Overview of the RFID Chip

Modern radio frequency identification (RFID) technology enables the transfer of data between an object bearing an RFID chip or tag and a sensor or interrogator without physical contact being made: the electronically encoded data in the chip is transmitted upon “interrogation” via electromagnetic fields of radio-frequency wavelength.

Some RFID tags must be read by their interrogating sensors at close range (not exceeding a few metres), but battery-powered chips can be read far more remotely and can be interrogated from distances of as much as several hundred metres. A major advantage of RFID technology over barcodes is that objects bearing the tags do not need to be within the direct line of the reader’s ‘vision’.

As they have become more widespread in industry, some civil liberties organisations have raised concerns that they may enable the reading of highly personalised information remotely without their users’ consent or even awareness.



The contemporary RFID device has its origins in ‘The Thing’, an espionage gadget devised by the Soviet inventor Léon Theremin in 1945: upon receiving radio waves, it retransmitted them in audio form and was used to eavesdrop covertly on secret transmissions. The link with modern RFID devices is that, like them, it was essentially “passive” and only became activated via waves from an external source.

By 1948, the radio engineer Harry Stockman had published a seminal paper (“Communication by Means of Reflected Power", Proceedings of the Institute of Radio Engineers, pp. 1196–1204, October 1948) which effectively opened the door to the development of modern RFID technology. At that stage, Stockman was aware that communication (or the sensing of electrical data) by reflected power required considerable technological development to become viable, but the seeds of the essential idea had been sewn.

A passive device demonstrated by its inventor, Mario Cardullo, to the New York Port Authority in 1971 was perhaps the very first genuinely RFID instrument to be developed (Cardullo acquired the patent for it in 1973). It was designed to function as a toll device and comprised a 16-bit memory with a transponder; as early as 1969, while he was developing his device, Cardullo had envisaged such technology being used in a vast range of applications, including: automated tolls, electronic licence plates, vehicle route guidance, electronic banking (such as electronic credit cards and cheque books); monitoring the performance of vehicles, improving security with RFID-tagged personnel; surveillance equipment and medicine in the form of patient history and identification.

In 1983, Charles Walton became the first inventor to have a device patented with the contemporary abbreviation RFID.


Technical aspects

RFID systems identify different objects by means of labels or tags implanted in or fixed to the item; these tags contain electronic information in the form of a tiny RFID chip. Sensors are then used to ‘interrogate’ the chip with radio frequency electromagnetic fields, which are transmitted to the object. Once the transmitted signal reaches the RFID chip, it causes the latter to respond with electromagnetic radio wavelengths which convey identification data. The sensors then “read” this data to identify which object is tagged. 

Broadly, there are three types of RFID chip: a passive chip, which requires the incoming signal transmitted by a sensor to activate its response, an active chip, which utilises a local power source such as a battery to regularly send out its signal, and a battery-assisted active chip which uses a small battery to amplify its response signal when a sensor or reader transmits an electromagnetic field to it. Passive chips are the least expensive.


While some tags are “read only”, meaning that they will only convey fixed identification data about a specific object which cannot be revised, others are designed to be “read-write”. Field operatives can revise the data encoded in these chips so that they can be used for different products. Some are revisable only once, while others can be revised multiple times.

RFID tags contain an RFID chip (integrated circuit) within which the data is stored and which includes a data processor for responding to the interrogator’s signal, as well as a radio frequency signaller and an antenna for picking up the sensor’s incident signal and transmitting a response. Electronically encoded data can be as simple as a unique serial number or as intricate as detailed product information.

Readers fall into one of two broad categories: PRAT (passive reader active tag) readers, which have the longest range at 1,000 – 2,000 feet, and ARPT (active reader passive tag) which activates the tag with its interrogation signal to transmit identifying information. The latter can also be used with battery-assisted tags.

Readers can be hand held or integrated into forklifts and other transportation vehicles or carts.


Product application - where the RFID Chip is used

In the space of the few decades since 1983, RFID technology has ramified through countless applications in industry, commerce, medicine, security services and even libraries. In 2009, for example, the American banking giants Wells Fargo and Bank of America announced that they would henceforth use passive RFID tags to track and identify every item in their data centres. Asset management in general, in fact, has now been transformed by RFID technology.

RFID inventory tracking reduced ‘out-of-stocks’ at the U.S. retail giant Wal-Mart by 30 per cent, and RFID tags are widely used in identification badges, which can be attached to an individual’s clothing or to a vehicle to facilitate automated access to high security areas.

The object to which the tag or RFID chip is attached can be reliably identified according to the stored data, enabling the accurate location of stock in warehouses, the progress of a new automobile along the production line during assembly, the tracking of goods during transportation and even for the identification of pets and livestock (RFID chips are often tiny, barely bigger than a grain of rice, and can be safely injected beneath the animal’s skin). In hazardous working environments such as off-shore oil rigs, safety can be enhanced because personnel can be identified at all times by wearing RFID tags on their clothing.


How the RFID Chip differs from other sensors

Because radio frequency electromagnetic fields are used in this technology for identification, objects with RFID tags do not need to be in the direct line of “vision” of a reader, as with barcode technology, for example. This makes them exceptionally versatile and, especially with passive tags, they are highly economic and can be used in huge numbers at relatively low cost.


Current product advantages and limitations

RFID offers manifest advantages over systems with manual features or use of bar codes. Tags covered by objects can be read if passed near a reader, as can tags that are situated inside containers such as cases, cartons or boxes. Unlike barcodes, RFID tags can also be batch read hundreds at a time.

While active tags have a far greater range than passive tags, they remain considerably more expensive and tend not to be used nearly as widely in industrial, commercial and medical sectors as a consequence.