A modified inter-digital capacitive (IDC) transducer for relative humidity (RH) measurement is fabricated by coating a thick film of polyvinyl alcohol (PVA) on the structure. The effective capacitance of the sensor, measured at 1MHz, increases with RH at room temperature. The RH sensing characteristics of PVA coated IDC transducer are analysed in terms of its sensitivity, dynamic range, frequency response, repeatability and recovery time. It is found that the stability of such a PVA based RH transducer improves remarkably by diffusing nanoparticles of CoFe2O4 in the PVA layer. A standard deviation of ± 0.05 and ± 0.01 for a sensitive layer with pure PVA and PVA-CoFe2O4 combination respectively results in a measurement error of ± 0.005 and ± 0.003.
BauskarDKaleBBPatilP (2012) Synthesis and humidity sensing properties of ZnSnO3 cubic crystallites. Sensors and Actuators B: Chemical161(1): 396–400.
2.
BlankTAEksperiandovaLPBelikovKN (2016) Recent trends of ceramic humidity sensors development: A review. Sensors and Actuators B: Chemical228: 416–442.
3.
BulaiGRusuOCazacuMM, et al. (2018) Structural, magnetic and humidity sensing properties of rare earth doped cobalt ferrite thin films synthesized by pulsed laser deposition. Journal of Ovonic Research Vol14(2): 119–128.
4.
ChenZLuC (2005) Humidity sensors: A review of materials and mechanisms. Sensor Letters3(4): 274–295.
5.
DelapierreGGrangeHChambaB, et al. (1983) Polymer-based capacitive humidity sensor: characteristics and experimental results. Sensors and Actuators4: 97–104.
6.
DeshkulkarniBViannieLRGanachariSV, et al. (2018) Humidity sensing using polyaniline/polyvinyl alcohol nanocomposite blend. In: IOP Conference Series: Materials Science and Engineering376(1): 012063.
7.
FangFFutterJMarkwitzAKennedyJ (2009) UV and humidity sensing properties of ZnO nanorods prepared by the arc discharge method. Nanotechnology20(24): 245502.
8.
FarahaniHWagiranRHamidonM (2014) Humidity sensors principle, mechanism, and fabrication technologies: A comprehensive review. Sensors14(5): 7881–7939.
9.
FengZSChenXJChenJJ, et al. (2012) A novel humidity sensor based on alumina nanowire films. Journal of Physics D: Applied Physics45(22): 225305.
10.
GinsonTJPhilipJ (2008) An inter-digital capacitive electrode modified as a pressure sensor. Sensors & Transducers Journal99(12): 25–32.
11.
HeYZhangTZhengW, et al. (2010) Humidity sensing properties of BaTiO3 nanofiber prepared via electro spinning. Sensors and Actuators B: Chemical146(1): 98–102.
12.
KimCHMyungYChoYJ, et al. (2009) Electronic structure of vertically aligned Mn-doped CoFe2O4 nanowires and their application as humidity sensors and photodetectors. The Journal of Physical Chemistry C113(17): 7085–7090.
13.
KotnalaRKShahJGuptaR (2013) Colossal humidoresistance in ceria added magnesium ferrite thin film by pulsed laser deposition. Sensors and Actuators B: Chemical181: 402–409.
14.
KuangQLaoCWangZL, et al. (2007) High-sensitivity humidity sensor based on a single SnO2 nanowire. Journal of the American Chemical Society129(19): 6070–6071.
15.
KumarYSharmaAShiragePM (2017) Shape-controlled CoFe2O4 nanoparticles as an excellent material for humidity sensing. RSC Advances7: 55778–55785.
16.
KumarYSharmaAShiragePM (2019) Impact of different morphologies of CoFe2O4 nanoparticles for tuning of structural, optical and magnetic properties. Journal of Alloys and Compounds778: 398–409.
17.
KurianMThankachanSNairDS, et al. (2015) Structural, magnetic, and acidic properties of cobalt ferrite nanoparticles synthesised by wet chemical methods. Journal of Advanced Ceramics4(3): 199–205.
18.
LiYYangMJCamaioniNCasalbore-MiceliG (2001) Humidity sensors based on polymer solid electrolytes: Investigation on the capacitive and resistive devices construction. Sensors and Actuators B: Chemical77(3): 625–631.
19.
LuYWangZYuanS, et al. (2013) Microwave-hydrothermal synthesis and humidity sensing behavior of ZrO 2 nanorods. RSC Advances3(29): 11707–11714.
20.
MamishevAVSundara-RajanKYangF, et al. (2004) Interdigital sensors and transducers. Proceedings of the IEEE92(5): 808–845.
21.
ManikandanVSikarwarSYadavBC, et al. (2018) Fabrication of tin substituted nickel ferrite (Sn-NiFe2O4) thin film and its application as opto-electronic humidity sensor. Sensors and Actuators A: Physical272: 267–273.
22.
NairDSKurianM (2017) Heterogeneous catalytic oxidation of persistent chlorinated organics over cobalt substituted zinc ferrite nanoparticles at mild conditions: Reaction kinetics and catalyst reusability studies. Journal of Environmental Chemical Engineering5(1): 964–974.
23.
PatilSNPawarAMTilekarSK, et al. (2016) Investigation of magnesium substituted nano particle zinc ferrites for relative humidity sensors. Sensors and Actuators A: Physical244: 35–43.
24.
PaulJPhilipJ (2017) Design optimization of a modified inter-digital capacitive transducer for non-invasive human body proximity sensing. Journal of Instrument Society of India47(3): 87–90.
25.
PenzaMCassanoG (2000) Relative humidity sensing by PVA-coated dual resonator SAW oscillator. Sensors and Actuators B: Chemical68(1–3): 300–306.
26.
ReddyLBMeghaRPrakashHR, et al. (2019) Copper ferrite-yttrium oxide (CFYO) nanocomposite as remarkable humidity sensor. Inorganic Chemistry Communications99: 180–188.
27.
SinghMYadavBCRanjanA, et al. (2017) Detection of liquefied petroleum gas below lowest explosion limit (LEL) using nanostructured hexagonal strontium ferrite thin film. Sensors and Actuators B: Chemical249: 96–104.
28.
UrbiztondoMPellejeroIRodriguezA, et al. (2011) Zeolite-coated interdigital capacitors for humidity sensing. Sensors and Actuators B: Chemical157(2): 450–459.
29.
VenturaIAZhouJLubineauG (2015) Investigating the inter-tube conduction mechanism in polycarbonate nanocomposites prepared with conductive polymer-coated carbon nanotubes. Nanoscale Research Letters10(1): 485.
30.
WangQPanYZHuangSS, et al. (2010) Resistive and capacitive response of nitrogen-doped TiO2 nanotubes film humidity sensor. Nanotechnology22(2): 025501.
31.
YangMRChenKS (1998) Humidity sensors using polyvinyl alcohol mixed with electrolytes. Sensors and Actuators B: Chemical49(3): 240–247.
Supplementary Material
Please find the following supplemental material available below.
For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.
For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.
