Remote Moisture Sensing utilizing Ordinary RFID Tags

Inkjet-Printed Humidity Sensor for Passive UHF RFID Systems

“…This type of measurement setup has been successfully used by other researchers working with RFID humidity sensors [25]. The reference tag is carefully designed to exhibit a certain frequency response, and only this tag is intended for this purpose.…”

RFID tag antenna based temperature sensing in the frequency domain

“…For example, Bhattacharyya et al examine the use of RFID tags as displacement and temperature threshold sensors by mapping displacements and temperature threshold violations to changes in the tag backscatter power strength [12], [13] as well as to the threshold transmitted power required from the reader to just turn on the tag IC [12]. Siden et al describe the construction of a humidity sensor based on this paradigm [14], while Marrocco et al discuss how the dielectric permittivity of different media can be monitored using this concept [15]. In [7] and [13], the authors make use of the fact that RFID performance degrades near metals to permanently detune the tag antenna on violation of a critical temperature threshold.…”

“…The RFID tag backscatter signal is also prone to fading and multipath in the environment of deployment, and sensor measurements based on signal amplitude strength are prone to significant noise. Furthermore, tag signal strength amplitude is dependent on the distance between the reader and tag antennas which is why many of the sensor designs [7], [13], [14] make measurements relative to a reference tag. The requirement of having a reference tag on the sensor packaging increases the form factor of these sensors which is undesirable.…”

Compact RFID Enabled Moisture Sensor

“…For seepage detection, RFID sensors can be embedded in walls. In moist surroundings, the difference in the backscattered received signal yields degradation in terms of dielectric losses [10]. Beside other applications, RFID tags are used in the field of agriculture.…”