TOPICAL REVIEW: Recent progress in carbon nanotube-based gas sensors (original) (raw)
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Carbon nanotubes based gas sensor
Carbon nanotube (CNT) based Gas sensors are attracting huge research interest as it gives high sensitivity, quick response, and stable sensors for industry, biomedicine, and more. The development of nanotechnology has opened a new gateway to build highly sensitive, cheap, portable sensors those who have low power consumption. The extremely high surface to volume ratio and the hollow structure of nanomaterials is perfect for the adsorption of gas molecules. Mainly, the advent of carbon nano-tubes has boosted the inventions of gas sensors that exploit CNTs unique morphology, geometry, and properties. Upon exposure to some gases, the changes in carbon nanotubes properties can be determined by many methods. Therefore, carbon nanotube-based gas sensors and their mechanisms are widely studied. In this paper, a broad survey of current carbon nanotubes based gas sensing technology is presented. Few experimental works done are reviewed. The types, fabrication, and the sensing mechanisms of the carbon nanotubes based gas sensors are discussed. The challenges of the research up to some extent are also addressed in this paper.
Carbon nanotubes transistors based Selective Gas sensors : from laboratory to mass production
2011
Carbon NanoTube (CNT) transistors have been known for several years to be extremely sensitive to gases and so to be very good candidate to become very effective sensors. This is the reason why scientists are focused on the gas sensor design, even if their production is still a challenge. In this article, we will present our approach to achieve large-scale production of reproducible devices using CNT mats deposited by a dynamic airbrush technique. After optimizing the CNT based solutions, we will demonstrate that we can fabricate large array of Carbon Nanotubes Field Effect Transistors (CNTFETs) with reproductible characteristics. Wa can obtain Drain/Source current on/off ratio of 1 to 5/6 orders, by controlling precisely the density of CNTs deposed. Thanks to these good transfer characteristics, the detection limit of these devices can be lowered under the ppm, and this for a large range of gases. The major issue for these sensors is their selectivity. To perform it, we have develop...
Carbon nanotubes as new materials for gas sensing applications
Journal of The European Ceramic Society, 2004
Carbon nanotubes (CNTs) deposited by plasma enhanced chemical vapor deposition on Si3N4/Si substrates provided with Pt electrodes have been investigated as resistive gas sensors towards NO2. The electrical response has been measured exposing the films to sub-ppm NO2 concentrations (10–100 ppb in dry air) at different operating temperatures ranging between 25 and 250 °C. The response to NO2 has been found to be at maximum at around 165 °C. Upon exposure to NO2 the electrical resistance of randomly oriented CNTs is found to decrease. The prepared films show reasonable dynamic of the electrical response and high reproducibility of the electrical properties. The resistance decrease of the CNTs when exposed to NO2 gas and the sensor response to concentrations as low as 10 ppb NO2, suggest the possibility to utilize CNTs as new sensors for air-quality monitoring.
Journal of Sensors, 2012
Miniaturized gas-sensing devices that use single-walled carbon nanotubes as active material have been fabricated using two different electrode materials, namely, Au/Cr and NbN. The resistive sensors have been assembled aligning by dielectrophoresis the nanotube bundles between 40 μm spaced Au/Cr or NbN multifinger electrodes. The sensing devices have been tested for detection of the H2S gas, in the concentration range 10–100 ppm, using N2as carrier gas. No resistance changes were detected using sensor fabricated with NbN electrodes, whereas the response of the sensor fabricated with Au/Cr electrodes was characterized by an increase of the resistance upon gas exposure. The main performances of this sensor are a detection limit for H2S of 10 ppm and a recovery time of few minutes. The present study suggests that the mechanism involved in H2S gas detection is not a direct charge transfer between molecules and nanotubes. The hypothesis is that detection occurs through passivation of the...