Passive UHF RFID enabled temperature sensor tag on cork substrate

The design of a fully passive RFID enabled temperature sensor implemented on cork substrate is presented. A passive UHF RFID tag is designed based on a commercial RFID chip and a 3D meandered dipole antenna. The antenna is fabricated by milling the radiating structure on copper tape and gluing it on a cork substrate of rectangular prism shape leading to a low profile design. The matching network of the tag chip is modified to include a thermistor element. It is optimized using electromagnetic simulation to maximize its impedance sensitivity to temperature variations thus successfully implementing a passive antenna based temperature sensor. A variation in temperature leads to a modification of the tag read range in frequency, which can be detected by a reader with frequency or power sweep capability. A UHF prototype is fabricated and measurements are presented demonstrating the sensing operation.