“…The porous alumina substrate from Kyocera (an excellent porous ceramic support for gas sensing experiments [ 24 , 25 ]) was the basis of the transducers, which contain two Au interdigital electrodes (IDE) on the front side, and a Pt heater on the backside (Fig. 1 ).…”
Section: Methodsmentioning
confidence: 99%
“… Fig. 1 Alumina transducer with: a Pt heater on the back side, b Au interdigital electrode (IDE) on the front side [ 25 ] …”
Recently the emissions of volatile organic compounds (VOCs) in the atmosphere have increased dramatically with rapid development of urbanization and industry. This led to a large decline in air quality around the world, which resulted in a heavy impact on human health. Therefore, new/cheap detection devices for VOCs are of high interest. Formaldehyde (FA) is a very toxic VOC, which damages the respiratory system even in the smallest doses and short exposure time. Zinc oxide (ZnO)/nickel oxide (NiO) heterostructures were synthesized using an economical route: firstly, NiO was prepared by liquid exfoliation technique and deposited by dip-coating on alumina ceramic transducers with two interdigital gold (Au) electrodes, followed by low—temperature hydrothermal growth of ZnO. The as-prepared sensors were characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM-EDAX), and X-Ray fluorescence (XRF). The response/recovery of ZnO/NiO heterostructure-based microsensors for formaldehyde was investigated at room temperature, in agreement with modern sensing requirements. The sensor operating voltage was varied between 1.5 and 5.0 V direct current (DC), to achieve the best sensor performance.
“…The porous alumina substrate from Kyocera (an excellent porous ceramic support for gas sensing experiments [ 24 , 25 ]) was the basis of the transducers, which contain two Au interdigital electrodes (IDE) on the front side, and a Pt heater on the backside (Fig. 1 ).…”
Section: Methodsmentioning
confidence: 99%
“… Fig. 1 Alumina transducer with: a Pt heater on the back side, b Au interdigital electrode (IDE) on the front side [ 25 ] …”
Recently the emissions of volatile organic compounds (VOCs) in the atmosphere have increased dramatically with rapid development of urbanization and industry. This led to a large decline in air quality around the world, which resulted in a heavy impact on human health. Therefore, new/cheap detection devices for VOCs are of high interest. Formaldehyde (FA) is a very toxic VOC, which damages the respiratory system even in the smallest doses and short exposure time. Zinc oxide (ZnO)/nickel oxide (NiO) heterostructures were synthesized using an economical route: firstly, NiO was prepared by liquid exfoliation technique and deposited by dip-coating on alumina ceramic transducers with two interdigital gold (Au) electrodes, followed by low—temperature hydrothermal growth of ZnO. The as-prepared sensors were characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM-EDAX), and X-Ray fluorescence (XRF). The response/recovery of ZnO/NiO heterostructure-based microsensors for formaldehyde was investigated at room temperature, in agreement with modern sensing requirements. The sensor operating voltage was varied between 1.5 and 5.0 V direct current (DC), to achieve the best sensor performance.
“…Detective sensors are essential for warning and protecting people from exposure of poisonous gases. A thin film of metal oxide semiconductors can be used as the sensing material [ 111 ], because their conductivity changes after adsorption of certain gases. For example, n-type metal oxides (CuO, SnO 2 , ZnO, and WO 3 ) are often used for conductometer sensors, because their higher carrier mobility than p-type metal oxides [ 112 , 113 ].…”
In the past two decades, we have learned a great deal about self-assembly of dendritic metal oxide structures, partially inspired by the nanostructures mimicking the aesthetic hierarchical structures of ferns and corals. The self-assembly process involves either anisotropic polycondensation or molecular recognition mechanisms. The major driving force for research in this field is due to the wide variety of applications in addition to the unique structures and properties of these dendritic nanostructures. Our purpose of this minireview is twofold: (1) to showcase what we have learned so far about how the self-assembly process occurs; and (2) to encourage people to use this type of material for drug delivery, renewable energy conversion and storage, biomaterials, and electronic noses.
“…It is proposed that a combination of these two concepts makes it possible to achieve better improvements in the manufacture of sensing devices and to enhance current fast-time and accurate responses [35,36].…”
The gas sensitivity of semiconductor metal oxides, such as γ-Fe2O3 and SnO2, is investigated together with the synergistic effects in conjunction with grapheme. Nanoparticles of γ-Fe2O3, γ-Fe2O3/SnO2, and γ-Fe2O3/SnO2/RGO, prepared by two-step fabrication, were assembled in gas-sensing devices to assess their sensitivities; response and recovery times for the detection of ethanol, methanol, isopropanol, formaldehyde, H2S, CO, and NO gases at different temperatures but constant concentrations of 100 particles per million (ppm); and H2S, which underwent the dynamic gas sensitivity test in different concentrations. Each sample’s crystallinity and microscopic morphology was investigated with X-ray diffraction and a scanning electron microscope. In comparative gas sensitivity measurements, the ternary composite of γ-Fe2O3/SnO2/RGO was identified as an ideal candidate, as it responds to all four tested liquids in the gas phase as well as H2S with a response value equal to 162.6. Further, only the ternary composite γ-Fe2O3/SnO2/RGO hybrid nanoparticles responded to NO gas with a sensor response value equal to 4.09 in 12 s. However, only the binary composite γ-Fe2O3/SnO2 responded to CO with a corresponding sensitivity of 1.59 units in 7 s.
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