Effects of Preparing Conditions on NO2-Sensing Properties of Sputtered WO3 Nano-Films

WO3 nano-films were deposited on Al2O3 substrate by dc reactive magnetron sputtering method. The effects of preparing conditions, such as the discharge gas ratio (Ar:O2), working pressure, sputtering time and annealing temperature on microstructure, crystalline state and NO2-sensing properties of WO3 nano-films were investigated by orthogonal trial experiment method. The optimum technological conditions were determined by orthogonal test and extreme difference analysis. The crystallization, morphology and composition of WO3 thin film obtained at the optimal parameters were studied by XRD, SEM and XPS. The gas sensing mechanism was also studied. WO3 nano-film shows high sensitivity, fast response, good selectivity at the best operating temperature 200°C.

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Polyaniline/SnO2 Nanocomposite Sensor for NO2 Gas Sensing at Low Operating Temperature

International Journal of Nanoscience ◽

10.1142/s0219581x15500118 ◽

2015 ◽

Vol 14 (04) ◽

pp. 1550011 ◽

Cited By ~ 8

Author(s):

A. Sharma ◽

M. Tomar ◽

V. Gupta ◽

A. Badola ◽

N. Goswami

Keyword(s):

Thin Films ◽

Gas Sensing ◽

High Sensitivity ◽

Morphological Properties ◽

X Ray Diffraction ◽

Chemical Route ◽

Sensing Properties ◽

Response Recovery ◽

Transmission Electron ◽

Gas Sensing Properties

In this paper gas sensing properties of 0.5–3% polyaniline (PAni) doped SnO 2 thin films sensors prepared by chemical route have been studied towards the trace level detection of NO 2 gas. The structural, optical and surface morphological properties of the PAni doped SnO 2 thin films were investigated by performing X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Raman spectroscopy measurements. A good correlation has been identified between the microstructural and gas sensing properties of these prepared sensors. Out of these films, 1% PAni doped SnO 2 sensor showed high sensitivity towards NO 2 gas along with a sensitivity of 3.01 × 102 at 40°C for 10 ppm of gas. On exposure to NO 2 gas, resistance of all sensors increased to a large extent, even greater than three orders of magnitude. These changes in resistance upon removal of NO 2 gas are found to be reversible in nature and the prepared composite film sensors showed good sensitivity with relatively faster response/recovery speeds.

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MWCNT Devices Fabricated by Dielectrophoresis: Study of Their Electrical Behavior Related to Deposited Nanotube Amount for Gas Sensing Applications

Journal of Integrated Circuits and Systems ◽

10.29292/jics.v10i1.400 ◽

2015 ◽

Vol 10 (1) ◽

pp. 13-20

Author(s):

Elisabete Galeazzo ◽

Marcos C. Moraes ◽

Henrique E. M. Peres ◽

Michel O. S. Dantas ◽

Victor G. C. Lobo ◽

...

Keyword(s):

Carbon Nanotubes ◽

Gas Sensing ◽

High Sensitivity ◽

Cost Effective ◽

Adsorbed Water ◽

Fast Response ◽

Process Time ◽

Electrical Behavior ◽

Glass Substrates ◽

Sensing Applications

Intensive research has been focused on investigating new sensing materials, such as carbon nanotubes (CNT) because of their promising characteristics. However, there are challenges related to their application in commercial devices such as sensitivity, compatibility, and complexity of miniaturization, among others. We report the study of the electrical behavior of devices composed by multi-walled carbon nanotubes (MWCNT) deposited between aluminum electrodes on glass substrates by means of dielectrophoresis (DEP), which is a simple and cost-effective method. The devices were fabricated by varying the DEP process time. Remarkable changes in their electric resistance were noticed depending on the MWCNT quantities deposited. Other electrical properties of devices such as high sensitivity, fast response time and stability are also characterized in humid environment. A humidity sensing mechanism is proposed on the basis of charge transfer between adsorbed water molecules and the MWNTC surface or between water and the glass surface.

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A Novel Type Room Temperature Surface Photovoltage Gas Sensor Device

10.20944/preprints201807.0572.v1 ◽

2018 ◽

Author(s):

Monika Kwoka ◽

Michal A. Borysiewicz ◽

Pawel Tomkiewicz ◽

Anna Piotrowska ◽

Jacek Szuber

Keyword(s):

Gas Sensor ◽

Room Temperature ◽

Gas Sensing ◽

Signal To Noise Ratio ◽

High Sensitivity ◽

Fast Response ◽

Surface Photovoltage ◽

Kelvin Probe ◽

Sensor Device ◽

Developed Surface

In this paper a novel type of a highly sensitive gas sensor device based on the surface photovoltage effect is described. The developed surface photovoltage gas sensor is based on a reverse Kelvin probe approach. As the active gas sensing electrode the porous ZnO nanostructured thin films are used deposited by the direct current (DC) reactive magnetron sputtering method exhibiting the nanocoral surface morphology combined with an evident surface nonstoichiometry related to the unintentional surface carbon and water vapor contaminations. Among others, the demonstrated SPV gas sensor device exhibits a high sensitivity of 1 ppm to NO2 with a signal to noise ratio of about 50 and a fast response time of several seconds under the room temperature conditions.

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Pd-Loaded In2O3 Hollow Spheres with Enhanced Formaldehyde Sensing at Low Temperature

NANO ◽

10.1142/s1793292021500065 ◽

2020 ◽

pp. 2150006

Author(s):

Xiaohua Liu ◽

Hong Wang ◽

Ruisong Yang ◽

Di Liu ◽

Jiawei Wan ◽

...

Keyword(s):

Gas Sensing ◽

Hollow Spheres ◽

Hollow Structure ◽

Average Diameter ◽

Fast Response ◽

Test Methods ◽

Step Method ◽

Sensing Properties ◽

Calcination Temperatures ◽

Working Temperature

The porous Pd-loaded In2O3 hollow spheres were successfully prepared by simple one-step method with the template of carbon spheres. The effect of calcination temperatures on morphology, composition and gas sensing performance of the as-obtained products was discussed by a series of test methods. The sample calcined at 550∘C showed uniform porous hollow spheres with an average diameter of 100[Formula: see text]nm. Gas-sensing results exhibited that the Pd-In2O3 hollow spheres-based sensor possessed excellent sensing properties to formaldehyde, which include high response value (33), low working temperature (180∘C) and fast response and recovery time (12[Formula: see text]s and 22[Formula: see text]s). The enhanced HCHO-sensing properties of Pd-In2O3 composites were attributed to the special porous and hollow structure, abundant oxygen vacancies and the catalysis of palladium. Pd-loaded In2O3 hollow spheres had been proved to be an ideal material for detecting HCHO at a low working temperature.

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Locally Controlled Sensing Properties of Stretchable Pressure Sensors Enabled by Micro-Patterned Piezoresistive Device Architecture

Sensors ◽

10.3390/s20226588 ◽

2020 ◽

Vol 20 (22) ◽

pp. 6588

Author(s):

Jun Ho Lee ◽

Jae Sang Heo ◽

Keon Woo Lee ◽

Jae Cheol Shin ◽

Jeong-Wan Jo ◽

...

Keyword(s):

Pressure Sensor ◽

Silver Nanowires ◽

Pressure Sensors ◽

High Sensitivity ◽

Fast Response ◽

Large Area ◽

Site Specific ◽

Sensing Properties ◽

Sensing Range ◽

Wide Range

For wearable health monitoring systems and soft robotics, stretchable/flexible pressure sensors have continuously drawn attention owing to a wide range of potential applications such as the detection of human physiological and activity signals, and electronic skin (e-skin). Here, we demonstrated a highly stretchable pressure sensor using silver nanowires (AgNWs) and photo-patternable polyurethane acrylate (PUA). In particular, the characteristics of the pressure sensors could be moderately controlled through a micro-patterned hole structure in the PUA spacer and size-designs of the patterned hole area. With the structural-tuning strategies, adequate control of the site-specific sensitivity in the range of 47~83 kPa−1 and in the sensing range from 0.1 to 20 kPa was achieved. Moreover, stacked AgNW/PUA/AgNW (APA) structural designed pressure sensors with mixed hole sizes of 10/200 µm and spacer thickness of 800 µm exhibited high sensitivity (~171.5 kPa−1) in the pressure sensing range of 0~20 kPa, fast response (100~110 ms), and high stretchability (40%). From the results, we envision that the effective structural-tuning strategy capable of controlling the sensing properties of the APA pressure sensor would be employed in a large-area stretchable pressure sensor system, which needs site-specific sensing properties, providing monolithic implementation by simply arranging appropriate micro-patterned hole architectures.

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Discriminable Sensing Response Behavior to Homogeneous Gases Based on n-ZnO/p-NiO Composites

Nanomaterials ◽

10.3390/nano10040785 ◽

2020 ◽

Vol 10 (4) ◽

pp. 785 ◽

Cited By ~ 24

Author(s):

Wen-Dong Zhou ◽

Davoud Dastan ◽

Jing Li ◽

Xi-Tao Yin ◽

Qi Wang

Keyword(s):

Gas Sensors ◽

Gas Sensing ◽

Sol Gel ◽

High Sensitivity ◽

Oxide Semiconductor ◽

Sensing Properties ◽

Gas Sensing Properties ◽

P Type ◽

Type Response ◽

Properties Of Composites

Metal oxide semiconductor (MOS) gas sensors have the advantages of high sensitivity, short response-recovery time and long-term stability. However, the shortcoming of poor discriminability of homogeneous gases limits their applications in gas sensors. It is well-known that the MOS materials have similar gas sensing responses to homogeneous gases such as CO and H2, so it is difficult for these gas sensors to distinguish the two gases. In this paper, simple sol–gel method was employed to obtain the ZnO–xNiO composites. Gas sensing performance results illustrated that the gas sensing properties of composites with x > 0.425 showed a p-type response to both CO and H2, while the gas sensing properties of composites with x < 0.425 showed an n-type response to both CO and H2. However, it was interesting that ZnO–0.425NiO showed a p-type response to CO but an discriminable response (n-type) to H2, which indicated that modulating the p-type or n-type semiconductor concentration in p-n composites could be an effective method with which to improve the discriminability of this type of gas sensor regarding CO and H2. The phenomenon of the special gas sensing behavior of ZnO–0.425NiO was explained based on the experimental observations and a range of characterization techniques, including XRD, HRTEM and XPS, in detail.

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Development of a High Stability Pd-Ni Alloy Thin-Film Coated SAW Device for Sensing Hydrogen

Sensors ◽

10.3390/s19163560 ◽

2019 ◽

Vol 19 (16) ◽

pp. 3560 ◽

Cited By ~ 3

Author(s):

Wen Wang ◽

Xueli Liu ◽

Shengchao Mei ◽

Mengwei Liu ◽

Chao Lu ◽

...

Keyword(s):

Thin Film ◽

High Sensitivity ◽

Hydrogen Sensor ◽

Fast Response ◽

Propagation Path ◽

Alloy Thin Film ◽

Optimal Parameters ◽

Ni Alloy ◽

Oscillation Loop ◽

Coated Surface

A Pd-Ni alloy thin-film coated surface acoustic wave (SAW) device is proposed for sensing hydrogen. The Pd-Ni thin-film was sputtered onto the SAW propagation path of a SAW device with a delay line pattern to build the chip-sized hydrogen sensor. The prepared sensor chip was characterized by employing a differential oscillation loop. The effect of the Pd-Ni film thickness on sensing performance was also evaluated, and optimal parameters were determined, allowing for fast response and high sensitivity. Excellent working stability (detection error of 3.7% in half a year), high sensitivity (21.3 kHz/%), and fast response (less than 10 s) were achieved from the 40 nm Pd-Ni alloy thin-film coated sensing device.

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MOFs-Derived Porous NiFe2O4 Nano-Octahedrons with Hollow Interiors for an Excellent Toluene Gas Sensor

Nanomaterials ◽

10.3390/nano9081059 ◽

2019 ◽

Vol 9 (8) ◽

pp. 1059 ◽

Cited By ~ 4

Author(s):

Yanlin Zhang ◽

Chaowei Jia ◽

Qiuyue Wang ◽

Quan Kong ◽

Gang Chen ◽

...

Keyword(s):

Gas Sensing ◽

Metal Organic Framework ◽

Fast Response ◽

Sensing Properties ◽

Gas Sensing Properties ◽

Metal Organic ◽

Response And Recovery ◽

Nife2o4 Nanoparticles ◽

Gas Molecules ◽

Ppm Level

Toluene is extensively used in many industrial products, which needs to be effectively detected by sensitive gas sensors even at low-ppm-level concentrations. Here, NiFe2O4 nano-octahedrons were calcinated from NiFe-bimetallic metal-organic framework (MOFs) octahedrons synthesized by a facile refluxing method. The co-existence of p-Phthalic acid (PTA) and 3,3-diaminobenzidine (DAB) promotes the formation of smooth NiFe-bimetallic MOFs octahedrons. After subsequent thermal treatment, a big weight loss (about 85%) transformed NiFe2O4 nanoparticles (30 nm) into NiFe2O4 porous nano-octahedrons with hollow interiors. The NiFe2O4 nano-octahedron based sensor exhibited excellent gas sensing properties for toluene with a nice stability, fast response, and recovery time (25 s/40 s to 100 ppm toluene), and a lower detection limitation (1 ppm) at 260 °C. The excellent toluene-sensing properties can not only be derived from the hollow interiors combined with porous nano-octahedrons to favor the diffusion of gas molecules, but also from the efficient catalytic activity of NiFe2O4 nanoparticles.

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Gas Sensing Properties of TiO2 and SnO2 Nanopowders Obtained through Gel Combustion

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.45.1828 ◽

2006 ◽

Vol 45 ◽

pp. 1828-1833

Author(s):

Fabio A. Deorsola ◽

P. Mossino ◽

Ignazio Amato ◽

Bruno DeBenedetti ◽

A. Bonavita ◽

...

Keyword(s):

Response Time ◽

Metal Oxides ◽

Gas Sensing ◽

Low Cost ◽

High Sensitivity ◽

Fast Response ◽

High Specific Surface Area ◽

Research Field ◽

Wide Range ◽

Gel Combustion

Nanostructured semiconductor metal oxides have played a central role in the gas sensing research field, because of their high sensitivity, selectivity and low response time. Among all the processes, developed for the synthesis of nanostructured metal oxides, gel combustion seems to be the most promising route due to low-cost precursors and simplicity of the process. It combines chemical gelation and combustion, involving the formation of a gel from an acqueous solution and an exothermic redox reaction, yielding to very porous and softly agglomerated nanopowders. In this work, nanostructured tin oxide, SnO2, and titanium oxide, TiO2, have been synthesized through gel combustion. Powders showed nanometric particle size and high specific surface area. The so-obtained TiO2 and SnO2 nanopowders have been used as sensitive element of resistive λ sensor and ethanol sensor respectively, realized depositing films of nanopowders dispersed in water onto alumina substrates provided with Pt contacts and heater. TiO2-based sensors showed at high temperature good response, fast response time, linearity in a wide range of O2 concentration and long-term stability. SnO2-based sensors have shown high sensitivity to low concentrations of ethanol at moderate temperature.

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