A Novel Passive RFID Temperature Sensor Using Liquid Crystal Elastomers

A passive RFID temperature sensor is presented. This sensor design utilizes a patch antenna integrated with a customized slot. Using a novel Liquid Crystal Elastomer (LCE) switch, the slot is shorted when the temperature reaches a specified threshold. When the temperature decreases below this threshold, the switch retracts to the original position. As a result, the antenna operates at one of two states corresponding to a controlled shift in frequency within the RFID band. Additionally, a single impedance matching network is designed to accommodate a favorable match between the two antenna states and the RFID IC.