RFID systems essentially perform the same work as commonly used barcodes: providing information about a product, pallet contents, or entire warehouse stocks. The most important feature of RFID is highlighted in its name: Radio Frequency Identification – a technology based on radio waves. Unlike barcodes, information does not need to be read by a laser, which is somewhat labor-intensive. The entire process takes place via radio transmission – instantly, automatically, and without direct physical contact. The basic principle is the same as in anti-theft systems in supermarkets, where labels trigger an alarm when detected by a transceiver located at the store exit.
Very thin transponders
An RFID system usually consists of two components: an RFID transponder, often called a TAG (which can store required information and looks like a credit card or a badge), and a reader with an antenna. The transponder is a combination of a microchip, usually smaller than a fingernail, and an antenna connected to the chip.
A number of different pieces of information can be saved on the chip, for example, those defined by the Electronic Product Code (EPC) standard. According to the EPC standard, we save information in the transponder about the place of origin of the product, its type, and its serial number. In the future, this information will be used to identify labeled objects worldwide.
RFID chips are produced in a read-write version, which means that data stored on the microchip can be easily updated. The transponder, usually integrated into a very thin label, is attached to pallets, packaging, or the products themselves – in other words, it is attached to items that require identification and management.
Reader solutions vary depending on where and how RFID systems are used. These can be small, handheld readers, or large reader gates used in cases of warehouse resource management or toll collection systems. Particularly powerful devices are capable of capturing a large number of chips simultaneously (bulk reading).
Active or passive transponder?
In order to locate radio chips, the reader emits radio waves, thereby generating an electromagnetic field. The tag with the chip reacts to the radio waves emitted by the reader (which is a transmitter, e.g., of radio waves) similar to a radio receiver. The reader registers this reaction and attempts to establish contact. The microchip then checks whether the reader is authorized to control it. Data transfer can only be carried out if the result of such a check is positive. There are two basic types of RFID systems – active and passive transponders. If the system uses passive transponders, the chips can be powered as follows: the transponder can convert the radio waves emitted by the reader into electrical energy, which is used to power the RFID chip, thus enabling it to communicate with the reader. The downside of passive transponders is their limited range, at best within a radius of a few meters. Usually, the reader must be placed as close as possible to locate the RFID chips. Thus, passive systems are better suited for reading company IDs, in anti-theft systems in supermarkets, or at sporting events for ticket control.
Unlike passive transponders, active transponders do not rely on an external power supply. Although they also use radio waves generated by the reader as a power source, these waves serve only for radio communication with the reader. Additionally, they are equipped with a mini-battery, enabling continuous operation of the microchip. This type of radio chip can store much more data than its passive counterpart and can also collect information without contact with a reader.
The chip can collect data about the environment, such as temperature and air pressure. This is particularly useful when dealing with perishable, fast-spoiling products. A good example is the transport of fish – a commodity particularly sensitive to temperature fluctuations. Using RFID technology in their transport, which often takes place over significant distances, allows for tracking the temperature they were exposed to from the moment of catch until delivery to a wholesaler or store, and whether they remained frozen the entire time. The chip can immediately “raise” an alarm if it detects any disruption in the cold chain.
Another beneficial feature of active transponders is their significantly greater range compared to passive ones (the range can reach up to several hundred meters). The negative feature of active chips is their reduced lifespan, to about four years (depending on their load). The reason is the battery power supply. Currently, scientists from the Fraunhofer Institute are working on ways to extend battery life to about ten years. RFID chips are being intensively researched, and experts expect that the first polymer-based chips – that is, not produced using silicon – will enter production before the end of this year.
Article prepared by DHL Express Sp. z o.o.