Highly sensitive chipless wireless relative humidity sensor based on polyvinyl-alcohol film

Abstract

This paper presents a chipless, highly sensitive, low profile, low cost and easily fabricated passive wireless relative humidity (RH) sensor. The sensor consists of a narrow band loop antenna loaded with PVA film coated interdigital capacitor (IDC) at 2.85 GHz. The RH sensor generates an amplitude peak at resonance in the radar cross section (RCS), which changes with different RH. The sensor is interrogated remotely by a reader antenna, and the measurement results show a good sensitivity up to 5.35 MHz/%RH above 50 % RH.

Environmentally-friendly cellulose nanofibre sheets for humidity sensing in microwave frequencies

“…Kapton polyimide and polyvinyl alcohol (PVOH) have been investigated for humidity sensing in RF/microwave frequencies, with the benefits of passive operation as well as integration with RFID technology [7,8]. The key advantage of Kapton is its compatibility with printing technologies [10,11] whereas PVOH has shown high sensitivity performances when used alone or when compared to Kapton [12,13]. A customized polymeric film synthetized from oxidianiline (ODA), m-pyromellitic dianhydride (m-PMDA), and N-methly-2-pyrrolidone (NMP) was also reported [9].…”

“…Only the best performances for each reference have been reported. Various sensing mechanisms have been investigated with PEL paper, Kapton and PVOH including (1) resonant frequency variation of LC-type resonator and stepped-impedance resonator[7,8,[12][13][14], and (2) radiated power variation of a RF integrated circuit connected with parallel plates sandwiching the sensitive substrate[11]. The highest sensitivity reported for PEL paper, Kapton and PVOH is respectively 0.53 MHz/%RH, 1.68 MHz/%RH and 6.75 MHz/%RH.…”

Patterned Ag/PI RFID Tag Integrated with Humidity Sensing by In Situ Metallization

“…RFID integrated with humidity sensors has attracted intensive attention, − which is capable of sensing and identification simultaneously. With the advantages of real-time, wireless, battery-free, and cost-efficient operation, chipless RFID tags with sensing materials are progressively becoming a hot topic. − However, most resonant antennas of chipless RFID tags for humidity sensing are fabricated by a coating and printing process, − which requires expensive equipment or high-quality inks and results in poor adherence. Furthermore, the existence of rigid substrates, such as silicon and glass, hinders their applications as well.…”

A Passive RFID Tag For Biomass Tracking

“…In the last two decades, researchers have been digging out different geometrical structures for chipless RFID tags. This has resulted in a variety of geometrical structures for resonators such as straight-line [11], spiral [12], 'C' and 'U' shape [3][13][14], circular and half-circle [15], elliptical [2], square [16], triangular [17], E-shaped micro strip [18], and ladder-shaped [19].…”