Towards a cheap, battery-less, wireless threshold temperature detector

A new method for cold chain logistics validation is presented in this paper. By combining RFID technology and polymer physical properties, a passive UHF RFID tag was designed on a special polymer that irreversibly shrink at certain temperature. With a power of 100 mW transmitted by a RFID UHF reader, the tag responds to 6 cm and after exceeding a threshold temperature, the read range decreases to 1.3 cm, As the tag is still responding but at a lower read range, we can deduce that it was not deliberately degraded and the decrease of read range is due to a temperature variation.