Wireless Ice Detection and Monitoring Using Flexible UHF RFID Tags

Abstract

Owing to its low relative permittivity, very few microwave sensors have been developed for monitoring ice deposition. This paper presents the first use of UHF RFID tags for wireless RF ice sensing applications. Despite its low permittivity, the existence of ice as a superstrate on a planar ultra-thin dipole antenna can lower the resonance frequency of the antenna significantly. The RFID tags, having a measured unloaded range of 9.4 m, were evaluated for remotely detecting the formation of ice in various scenarios up to 10 m from the reader, as well as monitoring the ice thawing, based on the Relative Signal Strength (RSS) in a phase-free approach. In most RSS-based sensing approaches, the tag's read-range is reduced as the RSS decreases in response to the stimulant. However, the proposed sensing mechanism does not reduce the tag's range; the ice superstrate improves the impedance matching of the tags and increases their radar cross section (RCS), resulting in a 10 m loaded read-range with over 12 dB ice-sensitivity, in an echoic multi-path environment. The proposed sensing mechanism achieves an accuracy of 86% for tags positioned between 0.5 and 10.5 m with various obstructions. When subjected to line-of-sight metallic obstruction, the sensor still maintains 80% accuracy. The long range and high sensitivity of the proposed sensing mechanics show that UHF RFID is a promising method for detecting the formation of ice in future smart cities.

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

“…As a result, the other sensors compared in the table such as humidity-sensitive polymers (PEDOT:PSS) [25] and thermal insulators [18] can be used to realize sensors aimed at other applications using the proposed antenna. Finally, while a rigid PCB was used to demonstrate this proof-of-concept, a range of fabrication techniques including screen printing [21] or photolithography on ultra-thin flexible polyimide laminates [11,13] can be used to realize the proposed design on inexpensive flexible or bio-degradable substrates.…”

“…A variety of Ultra-High Frequency (UHF) Rain TM [12], as well as chipless [4], RFID sensors have been realized based on integrating a sensing material that responds to external stimuli such as gases, humidity, or pH within the antenna. The sensor's response can then be read through the tag's received signal strength indicator (RSSI) [13], or in the case of chipless RFID, through the broadband transmission response influenced by the radar crosssection (RCS) [7]; however, using the magnitude of the RSSI introduces channel-dependent interference. Some sensors overcome the magnitude's fluctuations by interrogating the resonant frequency using a broadband threshold power or RSSI measurement [14].…”

“…Some sensors overcome the magnitude's fluctuations by interrogating the resonant frequency using a broadband threshold power or RSSI measurement [14]. Nevertheless, this approach requires a broadband reader that may not be permitted by local spectrum regulations, which limits the interrogation to either the 868 or 915 MHz band, with a bandwidth under 5 MHz; therefore, RSSI-based sensing is the most practical from a regulations point of view [13], as well as for compatibility with existing low-cost RFID readers. In order to overcome the distance-induced variations in the RSSI, a reference tag, not loaded with any sensing elements, is typically required [15].…”

Monitoring snowpack SWE and temperature using RFID tags as wireless sensors

“…Alternatively wet snow might be estimated and corrected for in the future, as already done with techniques for buried GPS or GPR (Schmid et al, 2015;Koch et al, 2019) or for moisture-sensing tags (Occhiuzzi et al, 2013;Caccami and Marrocco, 2018;Pichorim et al, 2018;Wang et al, 2020;Wagih and Shi, 2021).…”

“…on the tags (Nummela et al, 2008). Wagih and Shi (2021) exploited this last influence to sense-in the laboratory-the quantity of frost deposit on the tags antenna. However antenna-based sensing can characterize only the material touching the tag or a few millimeters away, and not the total volume of a snowpack.…”