Radio frequency identification (RFID) is an identification system that uses radio waves to send data, and RFID tags or transponders. The first patented RFID device was a passive radio transponder with an integrated memory by Mario Cardullo. At present, the technology has many applications, particularly in the retail industry because of its small size, low power demands and high levels of efficiency offered. The application of RFID is seen as the next generation of the barcode technology that is currently in use.
Types of RFID Tags
RFID tags or transponders come in two variants. The earlier variant of RFID tags is inductively coupled and is comprised of a microprocessor made of silicon, a coil of metal that acts as an antenna and glass or polymer covering. This type of RFID tags did not gain much attention from the retailer market because they were too expensive.
The latter version of RFID tags is capacitively coupled; it was developed in an effort to make RFID technology more affordable. Each capacitively coupled RFID tag is made up of a microprocessor made of silicon, carbon ink (this is conductive) that serves as the antenna and a paper substrate to which the chip is attached and on which the ink is printed. The small and relatively inexpensive materials used in production significantly lowered the price of each RFID tag. They have also made the tags more durable (tags that are capacitively coupled could work even when they are crumpled). The lower price comes at the cost of range, however. RFID tags of this type are limited to working within a few inches of the reader.
How RFID Tags Work
Passive RFID tags work in generally the same way, regardless of type. A reader sends out a radio frequency signal that gives just enough energy to activate the integrated circuit on the tag. Once the tag has been activated by the reader, it begins communicating with the latter. The tag modulates and changes the field (or backscatters the signal being sent out) in order to transfer data between it and the reader.
Active RFID tags work similarly with one exception: they are equipped with their own power source. Active RFID tags actively send out a signal to be picked up by the reader. Active RFID tags are larger than passive tags, but also have a larger range of operation, higher transmission power, better reliability and longer product life.
Research and development by several different entities are still ongoing to develop a cheaper and more effective passive RFID chip. Meanwhile, RFID tags are widely regarded as the next step after barcode technology in tracking and inventorying items. Wal-Mart, for instance, intends to invest in RFID technology.