RFID tag antenna based temperature sensing

Temperature monitoring is important in a number of fields, particularly cold supply chain applications. Most commercial wireless temperature sensors consist of transceivers, memory and batteries to maintain a temperature time history but this is expensive and allows for limited sensor deployment. In this paper, we propose a low cost temperature sensor based on the paradigm of passive RFID tag antenna based sensing. A simple mechanical method to permanently induce changes in RFID tag power characteristics upon exposure to temperatures greater than a threshold is presented. Critical temperature threshold violations can then be detected by monitoring received backscatter signal strength at a reader. The feasibility of the proposed hypothesis is examined via theoretical and experimental means. It will be shown that this sensing paradigm has the potential to greatly increase the pervasiveness of temperature sensing nodes and improve supply chain visibility and performance.