Advances in sensing mechanisms and micro/nanostructured sensing layers for surface acoustic wave-based gas sensors

Li, Xue; Sun, Wei; Fu, Wei; Lu, HF; Zu, Xiaotao; Guo, Yuanjun; Gibson, D. R.; Fu, Yong Qing

doi:10.1039/d2ta10014b

Cited by 24 publications

(6 citation statements)

References 221 publications

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“…15 Specifically, for SAW-based gas sensing applications, the sensitive material or sensing layer, which is coated onto SAW devices, is vital for its performance, as changes of sensing signals are strongly linked to perturbation of the sensing layer. 16 The layered structure is the core part of a SAW device, which typically consists of a piezoelectric substrate and an overlay layer (waveguide layer). Love-type waves are shear waves that can propagate through the waveguide layer, and the wave energy is concentrated on the surface of the layered structure.…”

Section: Introductionmentioning

confidence: 99%

“…Surface acoustic wave (SAW) devices are widely used in several fields such as medicine, dielectric detection, biochemistry, and communication. − The performance of SAW devices is directly influenced by the properties of the waveguide layer, such as piezoelectric films ZnO and AlN . Specifically, for SAW-based gas sensing applications, the sensitive material or sensing layer, which is coated onto SAW devices, is vital for its performance, as changes of sensing signals are strongly linked to perturbation of the sensing layer . The layered structure is the core part of a SAW device, which typically consists of a piezoelectric substrate and an overlay layer (waveguide layer).…”

Section: Introductionmentioning

confidence: 99%

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Piezoelectric Layered Structure with Conductive Polymer Composites as a Waveguide Layer: Swelling Monitoring Based on the Propagation of Love-Type Wave

Wu,

Chen,

et al. 2024

ACS Appl. Polym. Mater.

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Conductive polymer composites (CPCs), characterized by adjustable material parameters and specific responsiveness to external stimuli, exhibit potential utility as waveguide layers on surface acoustic wave (SAW) devices for monitoring applications. In this study, we examine the effect of swelling on the propagation of Love-type waves by subjecting a layered structure composed of a 36°Y-X lithium tantalate (LT) substrate and CPC waveguide layer. Love-type waves are first identified, and the propagation characteristics are analyzed by simulation and experimental comparison on polydimethylsiloxane (PDMS)-based CPC waveguide layers, which are filled with different acetylene carbon black (ACB) mass fractions. The influence of Love-type wave propagation after being subjected to a chemical medium is further explored. The results show that the characteristic frequency shifts of the SAW device are related to the observed swelling response of the ACB/PDMS CPCs. The experimental results are in agreement with simulations, and the frequency shifts with waveguide layer thickness variation are theoretically verified. This study illustrates the use of CPCs as a waveguide layer to modulate the propagation of Love-type waves and explores their application prospects for swelling monitoring.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Piezoelectric Layered Structure with Conductive Polymer Composites as a Waveguide Layer: Swelling Monitoring Based on the Propagation of Love-Type Wave

Wu,

Chen,

et al. 2024

ACS Appl. Polym. Mater.

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“…A large fraction of gas-sensing techniques is based on resistive gas sensors [4][5][6][7][8], the infrared absorption method [9][10][11][12], optical sensors [13][14][15], acoustic sensors [16][17][18][19], etc. Resistive gas sensors are highly praised for their high sensitivity, which can effectively convert changes in the gas sensing environment into unique resistance signals, thus enabling accurate detection of various gases.…”

Section: Introductionmentioning

confidence: 99%

Electrospun SnO2/WO3 Heterostructure Nanocomposite Fiber for Enhanced Acetone Vapor Detection

Lin,

Chang,

Hsieh

et al. 2023

Polymers

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Volatile organic compounds (VOCs), often invisible but potentially harmful, are prevalent in industrial and laboratory settings, posing health risks. Detecting VOCs in real-time with high sensitivity and low detection limits is crucial for human health and safety. The optical sensor, utilizing the gasochromic properties of sensing materials, offers a promising way of achieving rapid responses in ambient environments. In this study, we investigated the heterostructure of SnO2/WO3 nanoparticles and employed it as the primary detection component. Using the electrospinning technique, we fabricated a sensing fiber containing Ag NPs, poly(methyl methacrylate) (PMMA), and SnO2/WO3 (PMMA-Ag-SnO2/WO3) for acetone vapor detection. Following activation via UV/ozone treatment, we observed charge migration between WO3 and SnO2, resulting in a substantial generation of superoxide radicals on SnO2 nanoparticles. This phenomenon facilitates structural deformation of the fiber and alters the oxidation state of tungsten ions, ultimately leading to a significant change in extinction when exposed to acetone vapor. As a result, PMMA-Ag-SnO2/WO3 fiber achieves a detection limit of 100 ppm and a response time of 1.0 min for acetone detection. These findings represent an advancement in the development of sensitive and selective VOC sensing devices.

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“…The target gas absorption in the sensitive film alters the surface acoustic wave speed and accordingly modulates the amplitude or phase of the sensor output signal. The sensitive material significantly influences the sensitivity, response speed, and selectivity of the SAW gas sensor, and is therefore often a key part of SAW gas sensors [ 10 , 11 ].…”

Section: Introductionmentioning

confidence: 99%

A Nanoporous Polymer Modified with Hexafluoroisopropanol to Detect Dimethyl Methylphosphonate

Wang,

Li,

et al. 2023

Nanomaterials

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The increasing threat of nerve agents has prompted the need for gas sensors with fast response, high sensitivity, and good stability. In this work, the hexafluoroisopropanol functional group was modified on a porous aromatic framework material, which served as a sensitive material for detecting dimethyl methylphosphonate. A nerve agent sensor was made by coating sensitive materials on a surface acoustic wave device. Lots of pores in sensitive materials effectively increase the specific surface area and provide channels for diffusion of gas molecules. The introduction of hexafluoroisopropanols enables the sensor to specifically adsorb dimethyl methylphosphonate and improves the selectivity of the sensor. As a result, the developed gas sensor was able to detect dimethyl methylphosphonate at 0.8 ppm with response/recovery times of 29.8/43.8 s, and the detection limit of the gas sensor is about 0.11 ppm. The effects of temperature and humidity on the sensor were studied. The results show that the baseline of the sensor has a linear relationship with temperature and humidity, and the temperature and humidity have a significant effect on the response of the sensor. Furthermore, a device for real-time detection of nerve agent is reported. This work provides a new strategy for developing a gas sensor for detecting nerve agents.

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Advances in sensing mechanisms and micro/nanostructured sensing layers for surface acoustic wave-based gas sensors

Abstract: Surface acoustic wave (SAW) technology has been extensively used in communications and highly sensitive sensing applications. For SAW based gas sensing applications, the sensitive material or sensing layer which is...

Cited by 24 publications

References 221 publications

Piezoelectric Layered Structure with Conductive Polymer Composites as a Waveguide Layer: Swelling Monitoring Based on the Propagation of Love-Type Wave

Piezoelectric Layered Structure with Conductive Polymer Composites as a Waveguide Layer: Swelling Monitoring Based on the Propagation of Love-Type Wave

Electrospun SnO2/WO3 Heterostructure Nanocomposite Fiber for Enhanced Acetone Vapor Detection

A Nanoporous Polymer Modified with Hexafluoroisopropanol to Detect Dimethyl Methylphosphonate

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