scholarly journals Surface Modification of Carbon Nanotube Networked Films with Au Nanoclusters for Enhanced Gas Sensing Applications

2008 ◽  
Vol 2008 ◽  
pp. 1-8 ◽  
Author(s):  
M. Penza ◽  
R. Rossi ◽  
M. Alvisi ◽  
G. Cassano ◽  
M. A. Signore ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Gas Sensing ◽  
Chemical Vapor ◽  
Gas Sensitivity ◽  
Multiwalled Carbon ◽  
Sensing Applications ◽  
Sensor Temperature ◽  
P Type ◽  
Gas Response ◽  
Ppm Level

Multiwalled carbon nanotube (MWCNT) films have been deposited by using plasma-enhanced chemical vapor deposition (PECVD) system onto alumina substrates, provided with 6 nm thick cobalt (Co) growth catalyst for remarkably improved gas sensing, at working temperature in the range of 100–. Functionalization of the MWCNTs with nanoclusters of gold (Au) sputtering has been performed to modify the surface of carbon nanotube networked films for enhanced and specific gas detection up to sub-ppm level. It is demonstrated that the gas sensitivity of the MWCNT-based sensors depends on Au-loading used as surface-catalyst. The gas response of MWCNT-based chemiresistor is attributed top-typeconductivity in the Au-modified semiconducting MWCNTs with a very good short-term repeatability and faster recovery. The sensor temperature of maximum sensitivity of the Au-functionalized MWCNTs is found to decrease with increasing Au-loading on their surface, and continuous gas monitoring at ppb level of is effectively performed with Au-modified MWCNT chemiresistors.

Enhancement of the gas sensing performance of carbon nanotube networked films based on their electrophoretic functionalization with gold nanoparticles

2015 ◽  
Vol 1786 ◽  
pp. 37-42 ◽  
Author(s):  
E. Dilonardo ◽  
M. Penza ◽  
M. Alvisi ◽  
C. Di Franco ◽  
D. Suriano ◽  
...  
Keyword(s):  
Gas Sensors ◽  
Gas Sensing ◽  
Gas Sensitivity ◽  
Sensing Applications ◽  
Active Layers ◽  
Resistive Gas Sensors ◽  
Ppm Level ◽  
Fine Tune ◽  
Pollutant Gases ◽  
Higher Sensitivity

ABSTRACTControlled amounts of colloidal Au nanoparticles (NPs), electrochemically pre-synthesized, were directly deposited on MWCNTs sensor devices by electrophoresis. Pristine and Au-functionalized MWCNT networked films were tested as active layers in resistive gas sensors for detection of pollutant gases. Au-modified CNT-chemiresistor demonstrated higher sensitivity to NO2 detecting up to sub-ppm level compared to pristine one. The investigation of the cross-sensitivity towards other pollutant gases revealed the decrease of the sensitivity to NO2 with the increase of Au content, and, on the other side, the increase of that to H2S; therefore the fine tune of the metal loading on CNTs has allowed to control not only the gas sensitivity but also the selectivity towards a specific gaseous analyte. Finally, the sensing properties of Au-decorated CNT sensor seem to be promising in environmental and automotive gas sensing applications, based on low power consumption and moderate operating temperature.

scholarly journals Optimizing Paste Formulation for Improving the Performances of CMOS-Based MOx Chemiresistors Prepared by Ink-Jet Printing

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 774 ◽  
Author(s):  
Claudio Zuliani ◽  
Lisa Jerg ◽  
Alison Hart ◽  
Wolfram Simmendinger ◽  
Malick Camara ◽  
...  
Keyword(s):  
Gas Sensing ◽  
High Volume ◽  
Gas Sensitivity ◽  
Ink Jet Printing ◽  
Baseline Drift ◽  
Sensing Applications ◽  
Ink Jet ◽  
High Volume Production ◽  
Jet Printing ◽  
Gas Response

CMOS-based devices and the control of the materials properties by nanotechnology enabled significant progresses in the field of metal chemiresistors for gas sensing applications both in terms of miniaturization and performances (e.g., gas sensitivity). In this regard, ink-jet printing is a powerful technique to achieve high-volume production and meet the emerging consumer market demands. The paste formulation is an obvious aspect to consider for achieving a viscosity range suitable for ink-jet printing. More importantly, it is often an underestimated task which impacts the gas response of the resulting chemiresistors in terms of sensitivity, cross-sensitivity and baseline drift. In this manuscript, the effects on the film morphology and gas response upon removing ethyl-cellulose from the paste formulation is reported. Improvements in terms of sensitivity and baseline drift were observed.

scholarly journals The Effect of CH4 and CO2 Exposure on Carbon Nanotubes Electrical Resistance

2011 ◽  
Vol 214 ◽  
pp. 655-661 ◽  
Author(s):  
Amin Firouzi ◽  
Shafreeza Sobri ◽  
Faizah Mohd Yasin ◽  
Fakhru'l Razi Ahmadun
Keyword(s):  
Carbon Nanotubes ◽  
Electrical Resistance ◽  
Gas Sensing ◽  
Quartz Substrate ◽  
Chemical Vapor ◽  
High Sensitivity ◽  
Sensing Applications ◽  
Type Semiconductor ◽  
Adsorption Of Co2 ◽  
P Type

This research was carried out to monitor and investigate the gas sensing effects on carbon nanotubes (CNTs) by a systematic study of the variations in the electrical resistance as sensor signal induced by adsorption of CO2 and CH4 gaseous molecules. The CNTs were synthesized by Floating Catalyst Chemical Vapor Deposition (FC-CVD) method on quartz substrate under benzene bubble at temperature of 700°C. Then, they were tested for gas sensing applications operating at room temperature. Upon exposure to gaseous molecules, the electrical resistance of CNTs dramatically increased for both CO2 and CH4 gases with short response time and high sensitivity. It was also observed that the CNTs device behaves as a p-type semiconductor when exposed to gaseous molecules. In addition, the recovery of the sensors and mechanism of gas sensing procedure are discussed.

Property of NOx Gas Sensor Using Carbon Nanotube Prepared by Thermal CVD Method

2007 ◽  
Vol 124-126 ◽  
pp. 1253-1256 ◽  
Author(s):  
Tsuyoshi Ueda ◽  
Md. Mosharaf Hossain Bhuiyan ◽  
H. Norimatsu ◽  
S. Katsuki ◽  
Tomoaki Ikegami
Keyword(s):  
Carbon Nanotube ◽  
Gas Sensor ◽  
Gas Sensing ◽  
Chemical Vapor ◽  
Gas Concentration ◽  
Thermal Cvd ◽  
Cvd Method ◽  
Pt Electrodes ◽  
Measured Resistance ◽  
Sensor Temperature

Carbon nanotube (CNT) gas sensors for NOx gas detection were prepared. CNTs were grown on an Al2O3 substrate with interdigital Pt-electrodes (Al2O3 ceramic substrate) using both pulsed laser deposition (PLD) and thermal chemical vapor deposition (CVD) method. In this method, Al buffer layer and Fe catalytic thin film were prepared on the substrate by PLD method and then CNTs were grown by thermal CVD method. Surface images of CNTs on the substrates were observed by SEM, and the gas sensing property specific to NO gas was measured. Resistance of the prepared CNTs gas sensor decreased with increase of sensor temperature, and it decreased with increase of NO gas concentration at room temperature.

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.

scholarly journals A Review: Carbon Nanotube-Based Piezoresistive Strain Sensors

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Waris Obitayo ◽  
Tao Liu
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Composite Films ◽  
Strain Sensors ◽  
Voltage Response ◽  
Strain Sensing ◽  
Multiwalled Carbon ◽  
Sensing Applications ◽  
Mechanical Deformations ◽  
Electrical Resistivities

The use of carbon nanotubes for piezoresistive strain sensors has acquired significant attention due to its unique electromechanical properties. In this comprehensive review paper, we discussed some important aspects of carbon nanotubes for strain sensing at both the nanoscale and macroscale. Carbon nanotubes undergo changes in their band structures when subjected to mechanical deformations. This phenomenon makes them applicable for strain sensing applications. This paper signifies the type of carbon nanotubes best suitable for piezoresistive strain sensors. The electrical resistivities of carbon nanotube thin film increase linearly with strain, making it an ideal material for a piezoresistive strain sensor. Carbon nanotube composite films, which are usually fabricated by mixing small amounts of single-walled or multiwalled carbon nanotubes with selected polymers, have shown promising characteristics of piezoresistive strain sensors. Studies also show that carbon nanotubes display a stable and predictable voltage response as a function of temperature.

scholarly journals Room-temperature synthesis and CO2-gas sensitivity of bismuth oxide nanosensors

RSC Advances ◽  
2020 ◽  
Vol 10 (29) ◽  
pp. 17217-17227 ◽  
Author(s):  
Pritamkumar V. Shinde ◽  
Nanasaheb M. Shinde ◽  
Shoyebmohamad F. Shaikh ◽  
Damin Lee ◽  
Je Moon Yun ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Bismuth Oxide ◽  
Room Temperature ◽  
Gas Sensing ◽  
Deposition Method ◽  
Gas Sensitivity ◽  
Temperature Synthesis ◽  
Co2 Gas ◽  
Surface Areas ◽  
Sensing Applications

Room-temperature (27 °C) synthesis and carbon dioxide (CO2)-gas-sensing applications of bismuth oxide (Bi2O3) nanosensors obtained via a direct and superfast chemical-bath-deposition method (CBD) with different surface areas and structures.

A Strategy to Improve O2 Gas Response of La-SnO2 Nanofibers Based Sensor through Temperature Modulation

2019 ◽  
Vol 944 ◽  
pp. 657-665
Author(s):  
Ya Xiong ◽  
Hui Li ◽  
Tian Chao Guo ◽  
Qing Zhong Xue
Keyword(s):  
Gas Sensors ◽  
Gas Sensing ◽  
Operation Mode ◽  
Temperature Modulation ◽  
Oxide Semiconductors ◽  
Oxygen Ions ◽  
Isothermal Test ◽  
Sensor Temperature ◽  
Heating Energy Consumption ◽  
Gas Response

Generally sensing mechanisms of gas sensors based on metal-oxide semiconductors greatly depend on temperature, suggesting temperature modulation can be applied as a vital method to effectively enhance the sensor response. In this paper, we reported a strategy of quick-cooling operating temperature mode in the course of gas sensing process to elevate the O2 gas response while maintaining low heating energy consumption. La-SnO2 nanofibers synthesized by electrospinning were chosen as gas sensing materials. The O2 gas responses by employing quick-cooling operation mode are significantly improved compared with those obtained by traditional isothermal test. The improved O2 response is contributed to a higher coverage of negatively charged oxygen ions as a result of quick cooling. Our research offers a facile route to detect gas at low temperature with high response. More importantly, the strategy demonstrated here could also be extended to other gas sensor as long as its gas response is related to the sensor temperature.

Laser-Doped SiC as Wireless Remote Gas Sensor Based on Semiconductor Optics

2012 ◽  
Vol 717-720 ◽  
pp. 1195-1198
Author(s):  
Geunsik Lim ◽  
Tariq Manzur ◽  
Aravinda Kar
Keyword(s):  
Valence Band ◽  
Energy Gap ◽  
Gas Sensing ◽  
Optical Signal ◽  
Acceptor Level ◽  
Spectral Bands ◽  
Sensing Applications ◽  
Electro Optic ◽  
Midwave Infrared ◽  
P Type

An uncooled SiC-based electro-optic device is developed for gas sensing applications. P-type dopants Ga, Sc, P and Al are incorporated into an n-type crystalline 6H-SiC substrate by a laser doping technique for sensing CO2, CO, NO2 and NO gases, respectively. Each dopant creates an acceptor energy level within the bandgap of the substrate so that the energy gap between this acceptor level and the valence band matches the quantum of energy emitted by the gas of interest. The photons of the gas excite electrons from the valence band to the acceptor level, which alters the electron density in these two states. Consequently, the refractive index of the substrate changes, which, in turn, modifies the reflectivity of the substrate. This change in reflectivity represents the optical signal of the sensor, which is probed remotely with a laser such as a helium-neon laser. Although the midwave infrared (3-5 mm) band is studied in this paper, the approach is applicable to other spectral bands.

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