Temperature Sensing with Passive Ceramic RFID Tag

Radio frequency identification is a wireless technology that allows contactless readout of data from a passive device through time-modulated backscattering. High epsilon ceramic resonators, capable of shrinking interaction volumes by orders of magnitude, open new possibilities for developing long-range compact tags. Here we demonstrate that this technology also allows for accurate tracking after environmental temperature changes without an additional sensing circuit. Several material platforms, demonstrating significant permittivity temperature dependence, were explored and demonstrated less than a 1<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">○</sup>C sensitivity. Specifically, the passive tag, based on BaTiO3 with ε=500 and interrogated from a 4-meter distance, was demonstrated. Equipping high-index ceramic RFID tags with additional capabilities apart from their long reading ranges further promotes this technology in application to the Internet of Small Things, where small low-cost low-resource entities are foreseen to perform multiple functions.