Application of Polyvinylidene Fluoride Interdigital Capacitors as Parasitic Temperature-Sensing Loads in Passive HF RFID Transponders

摘要

In this work, the introduction of small variations in the electrical impedance of HF (High Frequency) RFID (Radio Frequency Identification) tags has been exploited in the proximity sensing of temperature by applying Polyvinylidene Fluoride (PVDF) interdigital capacitive sensors as a modification of the transponder's circuitry. The adopted electrical parasitic sensing load introduces a shift in the primary resonance peak of the tag. The impedance spectra have been acquired by a dedicated laboratory setup allowing to apply simultaneously thermal forcing and RF signals to the transponder itself. The sensitivity of the modified tag has been assessed after taking into account the thermal response of the transponder chip which is relevant in the formulation of thermal-sensing transponders.