Temperature sensor tag for passive UHF RFID systems

This paper presents a novel temperature sensor tag for passive UHF RFID systems and discusses a method to perform measurements in practice. The developed sensor tag is fabricated from cost-efficient and commercially available materials. Distilled water is used as the temperature sensitive material instead of the more traditional semi-conducting materials. The tag is fabricated on a FR-4 substrate which provides a rigid backing for the tag. The sensor can be constructed with a commercial passive UHF RFID IC. The temperature sensor tag's measurement range spans from a theoretical low of 0 up to over 74 °C. The read range of the tag, in free space, is over 7 metres.