Humidity Sensing by Polymer-Loaded UHF RFID Antennas

Abstract

Abstract-Passive ultra high-frequency radio frequency identification tags, besides item labeling, are also able to exploit capability to sense the physical state of the tagged object as well as of the surrounding environment. Here, a new family of polymer-doped tags are proposed and fully characterized for the detection of ambient humidity. A sensitive chemical species based on PEDOT:PSS is used to load a shaped slot, carved into a foldedlike patch tag. The communication and sensing capabilities of the resulting radio-sensor are investigated by means of simulation and measurements that show how to control and balance above opposite requirements by a proper deposition of the sensitive material. The device could have interesting applications in the assessment of the air quality within living and controlled rooms, in the monitoring of the conservation state of foods, in the preservation of walls, and even in the medical field, e.g., to monitor the healing of wounds.

RFID Technology for IoT-Based Personal Healthcare in Smart Spaces

“…Several CIM species have been experimented for applications to RFID sensors, mostly aimed at detecting humidity and ammonia by using carbon nano structures (CNTs), [3] conducting or insulating polymers [4]- [6] and even a simple blotting paper [7].…”

“…A change of 1% in the RH produces a 0.5 dB change in the backscattered power received by the reader. ground plane, the tag is suited to application over walls as well as over foods or drugs [4].…”

“…The estimated SAR is compliant even with the most restrictive European constraint for a distance roughly longer than from the reader which is fully compatible with the concept of remote monitoring. 4 More information available at: http://www.radio6ense.com/ProductsServices/night-care. 5 European Recommendations [33] impose the following rms limit to electric field emission in the UHF range:…”

Passive UHF RFID antennas for sensing applications: Principles, methods, and classifcations

“…The material used in this work is the commercial species Clevios PH 500, a dispersion for conductive coatings with PEDOT and PSS. Like other polymers containing sulfonic acid groups, PE-DOT:PSS is strongly hygroscopic and takes up moisture when handled under ambient conditions and consequently changes the Tag's radiation performances [46].…”

RFID antenna humidity sensor co-design for USN applications

“…RFID faces several critical challenges of cost, reliability and eco-friendliness when evaluating, planning and implementing it for most exciting unfolding era of Ubiquitous Sensor Networks (USN). However, the present sensor-enabled RFID solutions downgrade their effectiveness on account of extra cost [1] by employing additional components or materials [2,3,4] to achieve sensor module. Likewise, the vast fated implementation of sensor nodes demands a design with the capability of customizable calibration function in order to replicate it without additional costs.…”