Radio Frequency Identification
(RFID)
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Is an
automatic identification method, relying on storing and
remotely retrieving data using devices called RFID tags or
transponders. An RFID tag is a small object that can be
attached to or incorporated into a product, animal, or person.
RFID tags contain
silicon chips and
antennas to enable them to receive and respond to
radio-frequency queries from an RFID
transceiver. Passive tags require no internal power source,
whereas active tags require a power source. |
Types of RFID tags
RFID cards are also
known as "proximity" or "proxy" cards and come in three general
varieties: passive, semi-passive (also known as
semi-active), or active.
Passive
Passive RFID tags have
no internal power supply. The minute electrical current induced in the
antenna by the incoming radio frequency signal provides just enough
power for the CMOS integrated circuit (IC) in the tag to power up and
transmit a response. Most passive tags signal by
backscattering the carrier signal from the reader. This means that
the aerial (antenna) has to be designed to both collect power from the
incoming signal and also to transmit the outbound backscatter signal.
The response of a passive RFID tag is not just an ID number (GUID);
the tag chip can contain nonvolatile
EEPROM for storing data. Lack of an onboard power supply means
that the device can be quite small: commercially available products
exist that can be embedded under the skin.
As of 2006, the smallest such devices measured 0.15 mm × 0.15 mm,
and are thinner than a sheet of paper (7.5
micrometers).[4]
The lowest cost
EPC RFID tags which is the chosen standard by
Wal-Mart,
DOD,
Target,
Tesco in the UK and
Metro AG in Germany are available today at a price of
5 Cent each. The addition of the antenna creates a tag that varies
from the size of postage stamp to the size of a post card. Passive
tags have practical read distances ranging from about 10 cm (4 in.) (ISO
14443) up to a few meters (EPC
and
ISO 18000-6) depending on the
chosen radio frequency and antenna design/size. Due to their
simplicity in design they are also suitable for manufacture with a
printing process for the antennas. Passive RFID tags do not require
batteries, can be much smaller, and have an unlimited life span.
Non-silicon tags made from polymer semiconductors are currently being
developed by several companies globally. Simple laboratory printed
polymer tags operating at
13.56 MHz were demonstrated in
2005 by both PolyIC (Germany) and Philips (The Netherlands). If
successfully commercialized, polymer tags will be roll printable, like
a magazine, and much less expensive than silicon-based tags.
Semi-passive
Semi-passive RFID tags
are very similar to passive tags except for the addition of a small
battery. This battery allows the tag IC to be constantly powered,
which removes the need for the aerial to be designed to collect power
from the incoming signal. Aerials can therefore be optimized for the
backscattering signal. Semi-passive RFID tags are thus faster in
response, though less reliable and powerful than active tags.
Active
Unlike passive RFID
tags, active RFID tags have their own internal power source which is
used to power any ICs that generate the outgoing signal. Active tags
are typically much more reliable (e.g. fewer errors) than passive tags
due to the ability for active tags to conduct a "session" with a
reader. Active tags, due to their onboard power supply, also transmit
at higher power levels than passive tags, allowing them to be more
effective in "RF challenged" environments like water (including
humans/cattle, which are mostly water), heavy metal (shipping
containers, vehicles), or at longer distances. Many active tags have
practical ranges of hundreds of meters, and a battery life of up to 10
years. Some active RFID tags include sensors such as temperature
logging which have been used in concrete maturity monitoring or to
monitor the temperature of perishable goods. Other sensors that have
been married with active RFID include humidity, shock/vibration,
light, radiation, temperature and atmospherics like ethylene. Active
tags typically have much longer range (approximately 300 feet) and
larger memories than passive tags, as well as the ability to store
additional information sent by the transceiver. The United States
Department of Defense has successfully used active tags to reduce
logistics costs and improve supply chain visibility for more than 15
years. At present, the smallest active tags are about the size of a
coin and sell for a few dollars.
The RFID system
An RFID system may
consist of several components: tags, tag readers, edge servers,
middleware, and application software.
The purpose of an RFID
system is to enable data to be transmitted by a mobile 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
1932 [used the system identification to identify friendly and
un-friendly planes] . RFID quickly gained attention because of its
ability to track moving objects. As the technology is refined, more
pervasive and possibly invasive uses for RFID tags are in the works.
In a typical RFID
system, individual objects are equipped with a small, inexpensive tag.
The tag 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. The
application software on the host processes the data, often employing
Physical Markup Language (PML).
Take the example of
books in a library. Security gates can detect whether or not a book
has been properly checked out of the library. When users return items,
the security bit is re-set and the item record in the
Integrated library system is automatically updated. In some RFID
solutions a return receipt can be generated. At this point, materials
can be roughly sorted into bins by the return equipment. Inventory
wands provide a finer detail of sorting. This tool can be used to put
books into shelf-ready order.
RFID in inventory
systems
An advanced automatic
identification technology such as the Auto-ID system based on the
Radio Frequency Identification (RFID) technology has two values for
inventory systems. First, the visibility provided by this technology
allows an accurate knowledge on the inventory level by eliminating the
discrepancy between inventory record and physical inventory. Second,
the RFID technology can prevent or reduce the sources of errors.
Benefits of using RFID include the reduction of labor costs, the
simplification of business processes and the reduction of inventory
inaccuracies.
Human implants
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 |
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Hand
with the planned location of the RFID chip |
Just
after the operation to insert the RFID tag was completed |
Implantable RFID chips
designed for animal tagging are now being used in humans. An early
experiment with RFID implants was conducted by British professor of
cybernetics
Kevin Warwick, who implanted a chip in his arm in
1998. Night clubs in
Barcelona,
Spain and in
Rotterdam,
The Netherlands, use an implantable chip to identify their VIP
customers, who in turn use it to pay for drinks .
Regulation and
standardization
Some standards that
have been made regarding RFID technology include:
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ISO 11784 & 11785 - These standards regulate the Radio frequency
identification of animals in regards to Code Structure and Technical
concept
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ISO 14223/1 - Radio frequency identification of Animals,
advanced transponders - Air interface
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ISO 10536
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ISO 14443
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ISO 15693
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ISO 18000
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EPC global - this is the standardization framework that is most
likely to undergo International Standardisation according to ISO
rules as with all sound standards in the world, unless residing with
limited scope, as customs regulations, air-traffic regulations and
others. Currently the big distributors and governmental customers
are pushing EPC heavily as a standard well accepted in their
community, but not yet regarded as for salvation to the rest of the
world.
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