Screw tightening monitoring with RFID passive tag

The specific application of monitoring the tightening status of critical screws, e.g., screws for metallic structures which require high reliability, is herein discussed. A solution based on radio frequency identification (RFID) passive tag devices is proposed, and the design of a simple tag for metallic surfaces which allows for detecting the screw relaxing is presented. A tag prototype is manufactured on a 0.5 mm thick FR4 substrate of size 40 mm x 40 mm based on the commercial tag chip Impinj Monza R6 for working within the ultra-high frequency (UHF) FCC band 920.5-924.5 MHz, and measurement results reveal that the screw status can be detected up to a range of 2.5 m.