scholarly journals Growth of Defect-Induced Carbon Nanotubes for Low-Temperature Fruit Monitoring Sensor

Chemosensors ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 131
Author(s):  
Nagih M. Shaalan ◽  
Osama Saber ◽  
Faheem Ahmed ◽  
Abdullah Aljaafari ◽  
Shalendra Kumar
Keyword(s):  
Carbon Nanotubes ◽  
Low Temperature ◽  
Recovery Time ◽  
Smooth Surface ◽  
Operating Temperature ◽  
Sensor Response ◽  
Time Constants ◽  
Gas Concentration ◽  
Low Intensity ◽  
Response And Recovery

Herein, a carbon nanotubes-based sensor has been grown for the purpose of ethylene detection. The prepared CNTs had a crystalline structure with a smooth surface of 11.0 nm in diameter and 10.0 µm in length. The low-intensity graphite peak (G-band) as compared to the peak of the defect (D-band) characterizes the defects in the CNTs. An MWNTs-gas sensor was fabricated for monitoring the ethylene gas. The highest response was recorded at a low operating temperature of 30 °C. The sensor was also examined at 300 ppb up to 10 ppm and it showed a response of 2% up to 28%. The sensor response and recovery time constants were varied from 60 to 300 s, depending on the gas concentration. The results that were obtained for the synthetic ethylene gas were also compared with the real measurements for banana ripening. The results confirmed that the sensor is appropriate for the monitoring of fruit ripening.

Preparation and Property of Lanthanum Ferrite Formaldehyde Gas Sensor Modified by Carbon Nanotubes and Silver

2013 ◽  
Vol 320 ◽  
pp. 554-557 ◽  
Author(s):  
Yu Min Zhang ◽  
Yu Tao Lin ◽  
Jin Zhang ◽  
Zhong Qi Zhu ◽  
Qiang Liu ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Synthesis ◽  
Recovery Time ◽  
Gas Sensing ◽  
Operating Temperature ◽  
Sol Gel ◽  
Lanthanum Ferrite ◽  
Gas Sensing Properties ◽  
Response And Recovery ◽  
Sensitive Property

Our previous study revealed that the gas sensitive property of Silver-modified Lanthanum Ferrite (Ag-LaFeO3) is well, but the operating temperature is still high and the sensitivity also needs to be improved. This work based on our previous study. Ag-LaFeO3 was further modified by the Carbon nanoTubes (CNTs). The Ag-LaFeO3 powder modified with CNTs (CNTs-Ag-LaFeO3) was prepared by a sol-gel method combined with microwave chemical synthesis. The structure and gas-sensing properties were investigated. The results show that the structure of CNTs-Ag-LaFeO3 is of orthogonal perovskite. The sensitivity of 0.75% CNTs-Ag-LaFeO3 powder for 1 ppm formaldehyde is 13 at 86°C. The response and recovery time are 100s and 60s, respectively. Moreover, the sensor also has an obvious response for 1ppm formaldehyde at 58°C.

Synthesis, Structural and Gas Sensing Characterization of W-Doped SnO2 Nanostructures

2017 ◽  
Vol 381 ◽  
pp. 15-19 ◽  
Author(s):  
Mukesh Chander Bhatnagar ◽  
Anima Johari
Keyword(s):  
Low Temperature ◽  
Gas Sensors ◽  
Gas Sensing ◽  
Operating Temperature ◽  
Environmental Pollutants ◽  
Sensor Response ◽  
Gas Content ◽  
Temperature Sensitive ◽  
Oxide Material ◽  
Industry Waste

Tin oxide material has been extensively used for gas sensing application. Due to high operating temperature of metal oxide gas sensors, around 600 K and long term instability, research has been carried out to improve the material properties and reducing operating temperature. nanostructure materials have shown higher sensitivity and better stability towards gas environment. Air pollutants from automobiles and industry waste are the primary sources of environmental pollutants and there is need to develop low temperature, sensitive and selective gas sensors to monitor the gas content. In this paper, we have discussed the effect of Tungsten (W) doping in SnO2 nanostructures on the structural and gas sensing properties. The nanostructures have been synthesized by thermal evaporation process. The structural and surface morphology studies confirm the growth of nanowires on silicon substrates. The corresponding EDX spectra also confirm the doping of W into SnO2 nanowires. The gas sensor response of W-doped SnO2 nanowires was investigated upon exposure to various gases. It has been observed that doping of W enhances the NO2 sensitivity of nanowire based sensors at low temperature and the sensor response improves with increase in gas concentration.

scholarly journals 2D SnS2—A Material for Impedance-Based Low Temperature NOx Sensing?

Proceedings ◽  
2017 ◽  
Vol 1 (4) ◽  
pp. 455
Author(s):  
Daniela Schönauer-Kamin ◽  
Yongxiang Li ◽  
Wojtek Wlodarski ◽  
Samuel Ippolito ◽  
Ralf Moos
Keyword(s):  
Low Temperature ◽  
Operating Temperature ◽  
Total Concentration ◽  
Group Iv ◽  
Sensor Response ◽  
Two Dimensional ◽  
Sensor Signal ◽  
Tin Disulfide ◽  
Conductometric Transducer ◽  
Ppm Level

The sensor signal of tin disulfide (SnS2), a two-dimensional (2D) group-IV dichalcogenide, deposited as a film on a conductometric transducer is investigated at 130 °C. The focus is on the detection of the total NOx concentration. Therefore, the sensor response to NO and NO2 at ppm- and sub-ppm level at low operating temperature is determined. The results show that the sensing device provides a high sensor signal to NO and NO2 even at concentrations of only 390 ppb NOx. Both nitrous components, NO and NO2, yield the same signal, which offers the opportunity to sense the total concentration of NOx.

Thermal, optical and gas sensing properties of ZnO films prepared by different techniques

2018 ◽  
Vol 81 (1) ◽  
pp. 10101 ◽  
Author(s):  
Sonik Bhatia ◽  
Neha Verma ◽  
Munish Aggarwal
Keyword(s):  
Gas Sensor ◽  
Recovery Time ◽  
Gas Sensing ◽  
Operating Temperature ◽  
Sol Gel ◽  
Hexagonal Wurtzite Structure ◽  
Effect Of Temperature ◽  
Zno Films ◽  
Sensing Properties ◽  
Response And Recovery

Nowadays, for environmental protection, the use of portable gas sensor is essential to detect toxic gases. To control this problem of hazardous gases, metal oxide based sensors plays a vital role. In this recent study, Indium (2 at.wt.%) doped ZnO films has been prepared by sol gel spin coating and thermal evaporation techniques on glass substrates. To enhance the sensing properties, indium (In) was used as dopant and their annealing effect of temperature was observed. Thermal properties have shown the fruitful result that prepared films are useful for the fabrication of solar cell. Electrical properties revealed that capacitance and dielectric constant decreases with increase in frequency. X-ray Diffraction showed hexagonal wurtzite structure highly oriented along (1 0 1) plane. Field emission scanning electron microscope of these synthesis films prepared by different have shown the morphology as nanospheres having size of the order of 40–60 nm. 2.0 at.% of indium as modifier resulted in highest response and selectivity towards 5 ppm of NO2 gas at different operating temperature (50–200 °C). Highest sensitivity was obtained at operating temperature of 150 °C. Prepared films have quick response and recovery time in the range of 14–27 s and 67–63 s. The highest response and recovery time of gas sensor was explained by valence ion mechanism.

scholarly journals Enhancement of Gas Sensing Characteristics of Multiwalled Carbon Nanotubes by CF4Plasma Treatment for SF6Decomposition Component Detection

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Xiaoxing Zhang ◽  
Xiaoqing Wu ◽  
Bing Yang ◽  
Hanyan Xiao
Keyword(s):  
Carbon Nanotubes ◽  
Multiwalled Carbon Nanotubes ◽  
Recovery Time ◽  
Treatment Time ◽  
Gas Sensing ◽  
Gas Sensitivity ◽  
Multiwalled Carbon ◽  
State Evaluation ◽  
Response And Recovery ◽  
Sensing Characteristics

H2S and SO2are important gas components of decomposed SF6of partial discharge generated by insulation defects in gas-insulated switchgear (GIS). Therefore, H2S and SO2detection is important in the state evaluation and fault diagnosis of GIS. In this study, dielectric barrier discharge was used to generate CF4plasma and modify multiwalled carbon nanotubes (MWNTs). The nanotubes were plasma-treated at optimum discharge conditions under different treatment times (0.5, 1, 2, 5, 8, 10, and 12 min). Pristine and treated MWNTs were used as gas sensors to detect H2S and SO2. The effects of treatment time on gas sensitivity were analyzed. Results showed that the sensitivity, response, and recovery time of modified MWNTs to H2S were improved, but the recovery time of SO2was almost unchanged. At 10 min treatment time, the MWNTs showed good stability and reproducibility with better gas sensing properties compared with the other nanotubes.

Non-Linear Modeling of the Dynamic Response of Single-Wall Carbon Nanotube SWNT Composites to NO2 Gas in Air

2017 ◽  
Vol 886 ◽  
pp. 91-96
Author(s):  
Enas Abdulhay ◽  
Arwa Abdelhay ◽  
Borhan Aldeen Albiss ◽  
Rami Oweis
Keyword(s):  
Experimental Data ◽  
Carbon Nanotube ◽  
Operating Temperature ◽  
Sensor Response ◽  
Mathematical Equation ◽  
Linear Modeling ◽  
Single Wall Carbon Nanotube ◽  
Single Wall Carbon ◽  
Gas Concentration ◽  
Non Linear

The objective of this study is to develop a mathematical model, which can describe the response of a single-wall carbon nanotube (SWNT) as a resistive NO2 sensor, based on the acquired experimental data. The obtained non-linear regression attempts to simulate and predict the sensor response taking into account the effect of different variables such as NO2 concentration and operating temperature. The results show that the developed mathematical equation expresses the sensor response as a function of time, gas concentration, and temperature with an R-squared value ranging between 0.65 and 0.97.

scholarly journals NO2 Sensing with SWCNT Decorated by Nanoparticles in Temperature Pulsed Mode: Modeling and Characterization

Sensors ◽  
2020 ◽  
Vol 20 (17) ◽  
pp. 4729
Author(s):  
Enza Panzardi ◽  
Anna Lo Grasso ◽  
Valerio Vignoli ◽  
Marco Mugnaini ◽  
Pietro Lupetti ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Adsorption Kinetics ◽  
Gas Sensors ◽  
Variable Temperature ◽  
Surface Adsorption ◽  
Sensor Response ◽  
Single Wall Carbon Nanotubes ◽  
Gas Concentration ◽  
Pulsed Mode ◽  
Temperature Mode

In this paper, NO2 sensing by means of single-wall carbon nanotubes (SWCNT) networks, decorated with nanoparticles of TiO2 and Au, is proposed. In particular, it is shown that the performance of these materials can be enhanced using pulsed temperature mode. This sensing strategy effectiveness is theoretically and experimentally assessed. In this paper, in fact, a dynamic model for conductive gas sensors formed by networks of nanowires, considering the junctions between different wires as the main contribution to sensor conductance, and in the presence of the target gas, is presented and validated. The model accounts for variable temperature and gas concentration and sheds some light on the mechanisms leading to the sensor response improvement related to temperature pulsed working mode. It is also shown how the addition of a different material can be modeled through different surface adsorption kinetics.

Carbon Nanotube Gas Sensor Fabricated on Anodic Aluminum Oxide

2007 ◽  
Vol 124-126 ◽  
pp. 1309-1312
Author(s):  
Nguyen Duc Hoa ◽  
Nguyen Van Quy ◽  
Gyu Seok Choi ◽  
You Suk Cho ◽  
Se Young Jeong ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Gas Sensor ◽  
Chemical Vapor ◽  
Fast Response ◽  
Device Fabrication ◽  
Alumina Oxide ◽  
Response And Recovery ◽  
New Type ◽  
P Type

A new type of gas sensor was realized by directly depositing carbon nanotube on nano channels of the anodic alumina oxide (AAO) fabricated on p-type silicon substrate. The carbon nanotubes were synthesized by thermal chemical vapor deposition at a very high temperature of 1200 oC to improve the crystallinity. The device fabrication process was also developed. The contact of carbon nanotubes and p-type Si substrate showed a Schottky behavior, and the Schottky barrier height increased with exposure to gases while the overall conductivity decreased. The sensors showed fast response and recovery to ammonia gas upon the filling (400 mTorr) and evacuation.

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