RFID-Based Temperature Integrity Seal for “Cold Chain” Monitoring

In this work an innovative category of sensors, named “Temperature Integrity Seals” (TIS), designed specifically for Cold Chain monitoring is presented. Their purpose is to carefully ensure the continuous maintenance of low temperatures, with the primary goal of safeguarding the integrity of sensitive products such as food items, pharmaceuticals, and vaccines. The deployment of TIS addresses the crucial requirement for precise temperature control throughout the entire Cold Chain, ultimately guaranteeing the reliability and quality of perishable goods during storage and transportation. The TIS sensor employs innovative organic semiconductors featuring a molecular structure called “Photochromic Torsional Switch” (PTS). These semiconductors become conductive upon exposure to light, transitioning to a low-conductivity state after a specific amount of time. The sensor comprises a standard HF RFID tag partially coated with a layer of PTS compound, simulated numerically as a metal with variable conductivity in CST Microwave Studio. A consistent alteration in the tag input impedance is observed when the PTS compound shifts from ON (high conductivity state) to OFF (low conductivity state), confirming the device effectiveness as a temperature integrity sensor.