Highly sensitive surface acoustic wave (SAW) humidity sensors based on sol–gel SiO2 films: Investigations on the sensing property and mechanism

Tang, Yongliang; Li, Zhijie; Ma, Jianguo; Wang, Lu; Yang, Jin; Du, Bo; Yu, Qingkai; Zu, Xiaotao

doi:10.1016/j.snb.2015.03.069

Cited by 107 publications

(56 citation statements)

References 30 publications

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“…The core part of such a sensor is a SAW resonator coated with a sensitive film layer to act as frequency-changing component through the adsorption/chemical binding of ammonia molecules. The central frequency of the resonator can alter the conductivity (electric loading), effective mass (mass loading) or elastic modulus/density/viscosity (elastic loading) of the film [26][27][28][29]. Hence, for a good SAW based NH3 sensor, the sensitive film should be sensitive to one or all these variations when exposed to NH3 gas.…”

Section: Introductionmentioning

confidence: 99%

NH3 sensing property and mechanisms of quartz surface acoustic wave sensors deposited with SiO2, TiO2, and SiO2-TiO2 composite films

Tang

et al. 2018

Sensors and Actuators B: Chemical

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Northumbria University has developed Northumbria Research Link (NRL) to enable users to access the University's research output. Copyright © and moral rights for items on NRL are retained by the individual author(s) and/or other copyright owners. Single copies of full items can be reproduced, displayed or performed, and given to third parties in any format or medium for personal research or study, educational, or not-for-profit purposes without prior permission or charge, provided the authors, title and full bibliographic details are given, as well as a hyperlink and/or URL to the original metadata page. The content must not be changed in any way. Full items must not be sold commercially in any format or medium without formal permission of the copyright holder. The full policy is available online: http://nrl.northumbria.ac.uk/policies.html This document may differ from the final, published version of the research and has been made available online in accordance with publisher policies. To read and/or cite from the published version of the research, please visit the publisher's website (a subscription may be required.) This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. and SiO2-TiO2 films showed positive frequency shifts, whereas SiO2 film exhibits a negative frequency shift to NH3 gas. it is believed that the negative frequency shift was mainly caused by the increase of NH3 mass loading on the sensitive film while the positive frequency shift was associated to the condensation of the hydroxyl groups (-OH) on the film making the film stiffer and lighter, when exposed to NH3 gas. It demonstrated that humidity played a significant factor on the sensing performance. Comparative studies exhibited that the sensor based on the composite SiO2-TiO2 film had a much better sensitivity to NH3 at a low concentration level (1 ppm) with a response of 2 KHz, and also showed fast response and recovery, excellent selectivity, stability and reproducibility. Accepted Manuscript

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Section: Introductionmentioning

confidence: 99%

NH3 sensing property and mechanisms of quartz surface acoustic wave sensors deposited with SiO2, TiO2, and SiO2-TiO2 composite films

Tang

et al. 2018

Sensors and Actuators B: Chemical

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“…A number of methods have been developed for humidity detection, including capacitance [39][40][41][42], resistance [14], optic [43], microwave [44], magnetoelastic [17][18][19], surface acoustic wave [45], and quartz crystal microbalance (QCM) techniques [46,47]. In this study, a magnetoelastic sensor was used to detect humidity.…”

Section: Discussionmentioning

confidence: 99%

Magnetoelastic Humidity Sensors with TiO2 Nanotube Sensing Layers

Atalay

İzgi

Kolat

et al. 2020

Sensors

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In this study, TiO2 nanotubes (TiO2-NTs) are coated with a drop-casting method on Fe40Ni38Mo4B18 amorphous ferromagnetic ribbons and the humidity response of the prepared magnetoelastic sensors (MES) is investigated. The synthesis of TiO2-NTs is performed using a hydrothermal process. Sample characterization is carried out using X-ray diffraction and scanning electron microscopy. The results show that the sensors can measure moisture values in the range of 5% to 95% with very high precision and very low hysteresis. The humidity variation between 5% and 95% shows a change in the sensor resonance frequency of ~3180 Hz, which is a significant change compared to many magnetoelastic humidity sensors developed so far.

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“…TEM observations. 19,27 Hence, the response of our SAW humidity sensor is mainly due to the other two types of mechanism including the mass loading effect due to water adsorption and the acoustoelectric effect due to the conductivity alternation. 2b, the crystallographic structure was transformed to cubic NiO with a spacing of 0.210 nm.…”

Section: Characterizationmentioning

confidence: 99%

“…Different nanostructures with large surface-to-volume ratios such as nanoparticles, 5 nanowires, 3,15 nanosheets 16,17 and hierarchical nanostructures [18][19][20] have been extensively fabricated. Different nanostructures with large surface-to-volume ratios such as nanoparticles, 5 nanowires, 3,15 nanosheets 16,17 and hierarchical nanostructures [18][19][20] have been extensively fabricated.…”

Section: Introductionmentioning

confidence: 99%

Enhanced sensitivity of a GHz surface acoustic wave humidity sensor based on Ni(SO₄)_0.3(OH)_1.4 nanobelts and NiO nanoparticles

et al. 2015

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Ni(SO 4 ) 0.3 (OH) 1.4 nanobelts (NSOH NBs) and NiO nanoparticles (NPs) were used as the sensitive layers for a surface acoustic wave (SAW) humidity sensor. A high frequency SAW resonator up to 1.54 GHz was fabricated on a lithium niobate substrate as the sensing platform. The SAW sensors based on the NSOH NBs and the NiO NPs exhibited significantly decreased resonant frequencies with enhanced relative humidity (RH) from 11% to 85%, and the frequency response was found to be :2.95 MHz and :5.81 MHz, respectively. Both sensors showed rapid and reversible responses with excellent repeatability and long-term stability. The response and recovery times for NiO NPs were 23 s and 4 s, respectively. The NiO NP based sensor also showed negligible interference with various gases such as hydrogen and methane, demonstrating good cross-selectivity even while working in the GHz range. The high performance could be ascribed to the enhancement of the resonant frequency and the use of hydrophilic nanomaterials with a high surface-to-volume ratio.

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Highly sensitive surface acoustic wave (SAW) humidity sensors based on sol–gel SiO2 films: Investigations on the sensing property and mechanism

Cited by 107 publications

References 30 publications

NH3 sensing property and mechanisms of quartz surface acoustic wave sensors deposited with SiO2, TiO2, and SiO2-TiO2 composite films

NH3 sensing property and mechanisms of quartz surface acoustic wave sensors deposited with SiO2, TiO2, and SiO2-TiO2 composite films

Magnetoelastic Humidity Sensors with TiO2 Nanotube Sensing Layers

Enhanced sensitivity of a GHz surface acoustic wave humidity sensor based on Ni(SO₄)_0.3(OH)_1.4 nanobelts and NiO nanoparticles

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Highly sensitive surface acoustic wave (SAW) humidity sensors based on sol–gel SiO2 films: Investigations on the sensing property and mechanism

Cited by 107 publications

References 30 publications

NH3 sensing property and mechanisms of quartz surface acoustic wave sensors deposited with SiO2, TiO2, and SiO2-TiO2 composite films

NH3 sensing property and mechanisms of quartz surface acoustic wave sensors deposited with SiO2, TiO2, and SiO2-TiO2 composite films

Magnetoelastic Humidity Sensors with TiO2 Nanotube Sensing Layers

Enhanced sensitivity of a GHz surface acoustic wave humidity sensor based on Ni(SO4)0.3(OH)1.4 nanobelts and NiO nanoparticles

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Enhanced sensitivity of a GHz surface acoustic wave humidity sensor based on Ni(SO₄)_0.3(OH)_1.4 nanobelts and NiO nanoparticles