A Novel RFID sensor with conductive polymer for “cold chain” monitoring

This work introduces Temperature Integrity Seals (TIS) – a novel sensor class designed for Cold Chain monitoring. TIS aims to ensure precise low-temperature maintenance, safeguarding sensitive products like food, pharmaceuticals, and vaccines. The implementation of TIS seeks to address the critical need for precise temperature control throughout the entire Cold Chain, thereby ensuring the reliability and quality of perishable goods during storage and transportation. Implemented with innovative organic semiconductors called "Photochromic Torsional Switch" (PTS), TIS sensors exploits the unique property of these semiconductors to become conductive through light activation, with a subsequent transition to a low-conductivity state after a specific time interval. The sensor consists of a standard HF RFID tag where a portion of one arm is partially replaced with a trace of the PTS compound, numerically modelled as a metal with a variable conductivity in CST Microwave Studio. A consistent variation of the tag input impedance can be observed when the PTS compound changes its state from ON (high conductivity state) to OFF (low conductivity state). This confirms the effectiveness of the device as a temperature integrity sensor.