Development of a chipless RFID temperature sensor using cascaded spiral resonators

In this paper a fully printable low cost chipless RFID temperature sensor is presented. The chipless RFID comprises of multiresonator spirals coupled with a microstrip line. Each spiral represents a single data bit and the number of cascaded spirals corresponds to the number of bits it can store. The integration of temperature sensing is performed by utilizing the resonant frequency of a specific spiral of the tag. Unlike earlier reported works on chipless RFID temperature sensor our proposed sensor does not require any external circuitry or semiconductor chip for sensing environment temperature. Rather, it performs real time temperature sensing using the dielectric property of temperature dependent high K polyamides. Introducing high K dielectric material changes the equivalent capacitance of the LC resonator which varies with environment temperature. Results verify that a dedicated resonator can perform the sensing whereas the other cascaded resonators resemble the ID of the tag.