Low-Cost, Ubiquitous RFID-Tag-Antenna-Based Sensing

TLDR

RFID is a proven technology for track‑and‑trace applications. This work investigates using RFID tags as low‑cost sensors by mapping physical parameter changes to controlled antenna property variations and designing permanent changes for threshold detection. The authors achieve this by altering tag antenna geometry or boundary conditions to create a memory effect, and demonstrate three sensor prototypes for displacement, temperature thresholds, and fluid level. The results indicate that RFID‑tag‑antenna sensing could transform domains requiring inexpensive, durable, ubiquitous sensors.

Abstract

Radio-frequency identification (RFID) has been well established as an effective technology for track and trace applications. In this paper, we go beyond the ID in RFID, and discuss the potential for RFID tags to be used as low-cost sensors by mapping a change in some physical parameter of interest to a controlled change in RFID tag antenna electrical properties. We will also show that it is possible to design the tag antenna to suffer a permanent change in case of violation of a critical threshold in the parameter of interest thereby creating a low-cost threshold sensing mechanism. This can be achieved by inducing controlled changes to the tag antenna geometry parameters or to the antenna boundary conditions, in effect creating a nonelectric memory to monitor state. After identifying the application space for which this class of sensing is well suited, we present details into the design and testing of three different kinds of sensors based on this sensing paradigm. We demonstrate how we use this concept to sense displacements, temperature thresholds, and fluid levels. We will show that RFID-tag-antenna-based sensing has the potential to revolutionize application domains in which there is a need for low-cost, long-lasting, ubiquitous sensors.