Identification of Humidity Sensing Mechanism in MgAl2O4 by Impedance Spectroscopy as Function of Relative Humidity

Crochemore, G.B.; Ito, Amadeu Rodrigues Pereira; Goulart, Celso Antonio; Souza, D. P. F. de

doi:10.1590/1980-5373-mr-2017-0729

Cited by 13 publications

(3 citation statements)

References 21 publications

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“…Typically, literature reports the results of Hg porosimetry measurements of materials used to make air humidity sensors [27][28][29] , in the form of powders or sintered compacts, even for sensors made using the thick film paste screen printed technique [30]. Unfortunately, with this approach, the contribution of the thick film paste preparation process and additional heating treatment to porosity of the sensory material remains unclear, although two consecutive measurements of the peeled material (powder) from the sensor substrate (after thick film paste preparation procedure and calcinations) can be of great help [31].…”

Section: Mercury Porosimetry Of Powder and Thick Film Samplesmentioning

confidence: 99%

Structural, morphological and textural properties of iron manganite (FeMnO3) thick films applied for humidity sensing

Nikolić

Krstić

Labus

et al. 2020

Materials Science and Engineering: B

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Iron manganite (FeMnO 3 ) powder with a cubic (bixbyite, ̅ ) crystal structure was obtained by a solid state reaction. Thick film paste (powder + organic vehicles) was screen printed on alumina substrate with test interdigitated PdAg electrodes. Significant porosity (60.6%) composed of macropores (larger than 100 nm) was determined by Hg porosimetry, changing only slightly from the first extrusion run indicating a stable pore system. Hg porosimetry evaluation of thick film samples enabled estimation of true textural parameters of the thick film compared to powder. Impedance response of the thick film sensor was monitored in a humidity chamber in the relative humidity range 30-90%, at room temperature (25 o C) and frequency range from 42 Hz to 1 MHz. At 100 Hz the impedance reduced from 10.41 MΩ to 0.68 MΩ for relative humidity of 30 and 90%, respectively. Analysis of complex impedance using an equivalent circuit showed the dominant influence of grain boundaries. The sensor response and recovery was fast (several seconds) and a relatively low hysteresis value of 2.8% was obtained.

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Section: Mercury Porosimetry Of Powder and Thick Film Samplesmentioning

confidence: 99%

Structural, morphological and textural properties of iron manganite (FeMnO3) thick films applied for humidity sensing

Nikolić

Krstić

Labus

et al. 2020

Materials Science and Engineering: B

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“…Some of the most recent relative humidity sensors have employed new materials as moisture-sensitive layers. These materials include porous ceramic oxides [9], [10], polymers [11], [12], and electrolytes [13], [14]. Ceramic oxides can be prepared by conventional or advanced processing, and their extensive use as humidity sensors is due to their hydrophilic nature, so water vapor can easily penetrate through the pore openings.…”

Section: Introductionmentioning

confidence: 99%

The Effect of SnO2 Mixture on a PVA-Based Thick Film Relative Humidity Sensor

Wiranto¹,

Martadi²,

Sulthoni³

et al. 2022

International Journal on Advanced Science, Engineering and Information Technology

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In this research, thick film technology has been used to design and fabricate relative humidity sensors with Polyvinyl Alcohol (PVA) as the sensing layer. The design was optimized to produce an ideal geometry according to the limitations of thick film technology. The sensor fabrication process used screen printing techniques on Alumina (Al2O3) substrate with Silver (Ag) as the electrode material. SnO2 was added to the PVA sensing layer with variations in the composition of 1:1 and 1:2. FTIR analysis showed that the addition of SnO2 did not affect the structure of the PVA, which indicated that there was no chemical reaction between PVA and SnO2. The deposition of the sensing layer was carried out using spin coating method, and the fabricated sensors were then tested by varying 5 humidity points inside a chamber with a hygrometer as a reference. Based on the test results, it was found that the sensors showed responses to humidity variation in the form of changes in resistance values. When the humidity in the chamber increased, the sensor resistance value decreased. The addition of SnO2 could reduce the relatively high resistance value of the PVA-based humidity sensor and also increase the sensor's time response to humidity variation. However, the humidity sensor's sensitivity decreased for the higher composition of SnO2. With this technique, a simple yet stable humidity sensor could be fabricated using thick-film technology with a wide range of potential applications.

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“…As RH continues to increase, water molecules occupy the inter-particle voids forming bridges between grain boundaries assisting ionic conduction through both H + and H3O + hopping [57].…”

Section: Effect Of Humiditymentioning

confidence: 99%

Co-doped ZnO Nanowires for Low Temperature Methane Sensing Operational in Humid Environments

Morrin¹,

Datta²

2020

Preprint

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<p>Sensitive and selective detection of methane is essential due to its role in the greenhouse effect, relevance to industrial safety and recently discovered importance as a biomarker for gastrointestinal health. However, obtaining a reliable response to low concentrations (<100 ppm) of methane at low temperatures, especially in presence of humidity still remains a great challenge. In this work, a metal-oxide based sensor capable of low methane concentration detection and humidity resistance is reported. Chemiresistive sensors based on ZnO nanowire films were grown by a hydrothermal process and doped with Co. In terms of methane detection, Co-doping of the ZnO nanowires enabled the sensor to operate optimally at the low operating temperature of 50<sup>o</sup>C and an improved sensitivity of response (lowest measured concentration: 1 ppm) was observed when compared to that of pure ZnO nanowire films. This increased sensitivity was attributed to an increase in donor-type vacancies and enhanced oxygen adsorption on the surface. A mesoporous silica molecular sieve was further integrated as a moisture filter layer to mitigate the effect of humidity. It is envisaged that based on the sensors’ performance characteristics reported here, that the sensor could be applicable for emerging diagnostic applications tracking methane emissions from the breath. </p>

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Identification of Humidity Sensing Mechanism in MgAl2O4 by Impedance Spectroscopy as Function of Relative Humidity

Cited by 13 publications

References 21 publications

Structural, morphological and textural properties of iron manganite (FeMnO3) thick films applied for humidity sensing

Structural, morphological and textural properties of iron manganite (FeMnO3) thick films applied for humidity sensing

The Effect of SnO2 Mixture on a PVA-Based Thick Film Relative Humidity Sensor

Co-doped ZnO Nanowires for Low Temperature Methane Sensing Operational in Humid Environments

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