Battery-Free Wireless Light-Sensing Tag Based on a Long-Range Dual-Port Dual-Polarized RFID Platform

Abstract

Radio frequency identification (RFID) represents an emerging platform for passive RF-powered wireless sensing. Differential Multi-port RFID systems are widely used to enable multiple independent measurands to be gathered, or to overcome channel variations. This paper presents a dual-port/dual-integrated circuit (IC) RFID sensing tag based on a shared aperture dual-polarized microstrip antenna. The tag can be loaded with different sensors where the received signal strength indicator (RSSI) of one IC is modulated using a sensor, and the other acts as a measurand-insensitive reference, for differential sensing. The 868 MHz tag maintains a minimum unloaded read range of 14 m insensitive to deployment on metals or lossy objects, which represents the longest reported range of a multi-port RFID sensing tag. The tag is loaded with a light-dependent resistor (LDR) to demonstrate its functionality as a battery-less wireless RFID light sensor. Following detailed RF characterization of the LDR, it is shown that the impedance, and consequently the RSSI, of the sensing tag are modulated by changing the light intensity, whereas the reference port maintains a mostly unchanged response for a correlated channel. The proposed tag shows the potential for channel variations-tolerant differential RFID sensing platforms based on polarization-diversity antennas.

Wide-range soft anisotropic thermistor with a direct wireless radio frequency interface

“…dielectric changes due to soil moisture variation or ice accumulation 21 , 22 , or vital signs using wearable antennas 23 . Moreover, RF sensor readout has been widely used based on additional functional sensors including 2D materials 24 , conductive polymers 25 , 26 , inorganic sensitive materials 27 , lumped sensors 28 , and even bacterial cultures 29 . For gas sensing, it was shown that reading the response of resistive sensors at kHz frequencies can improve their linearity and sensitivity 30 .…”

UHF RFID and NFC Point-of-Care—Architecture, Security, and Implementation

“…Changes were made to this version by the publisher prior to publication. The final version of record is available at http://dx.doi.org/10.1109/JRFID.2023.3268422 body phenomena, including variations of temperature [12], humidity [22], pressure [23] and light [24]. Table I reports examples of the most assessed sensing helpful for PoCs that can be categorized into three types: i) physical, ii) behavioural, and iii) chemical.…”

RFID-Enabled Energy Harvesting using Unidirectional Electrically-Small Rectenna Arrays

“…RFID sensing has the advantage of relying on a single low-cost RFID IC for providing the unique ID of the backscattered RF signal that is amplitude-modulated by the measurand. RFID sensing has been incorporated in various applications ranging from vital signs monitoring using textile antennas [2], supply chain security [3], [4], wireless ice detection [5], as well as loaded by sensors for on-body temperature sensing [6] or indoor light intensity monitoring [7].…”