Chipless RFID and Wireless Metamaterial Sensors
Filippo Costa, University of Pisa, Italy
Etienne Perret, University of Grenoble Alpes, France
Sensors need to be identifiable, easy to use, and potentially low-cost, able to fulfill the pressing need to make objects able to communicate with one another. RFID is becoming an attractive technology for low-cost sensors. RFID sensors are based on an RFID tag loaded with an additional circuit where the sensing component is installed. Even if battery free, these sensors are still based on an electronic circuit. An alternative tough challenging approach to sense the environment wirelessly is to use an entirely passive device without any electronic circuit. In this case the information is embedded in the electromagnetic footprint of a resonator and the sensing is carried out by detecting the changes of the electromagnetic response of the device. Indeed, as every electromagnetic device, the radio frequency response of these tags is dependent on the electric or magnetic changes of nearby substrates or particles and on the variation of external environment. If these variations are opportunely controlled and isolated, an indirect
measurement of several environmental quantities, or mechanical changes, can be extracted from the measured backscattering spectrum. This category of sensors takes the name of chipless RFID sensors or metamaterial wireless sensors. This technology could be very appealing for designing very low cost, green and embedded sensors. The absence of a chip and a battery gives the opportunity to dramatically decrease the cost of the sensor and to achieve infinite lifetime. Given the absence of any electronic circuit, chipless RFID sensors are potentially suitable for hazardous environments.