Recognizing Physisorption and Chemisorption in Carbon Nanotubes Gas Sensors by Double Exponential Fitting of the Response

Gas sensing continues attracting research communities due to its potential applications in the sectors military, industrial and commercial. A special emphasis is placed on the use of carbon nanomaterials such as carbon nanotubes and graphene, as sensing materials. The chapter will be divided as follows: In the first part, a description of the main topologies and materials (carbon nanomaterials plus polymers, metals, ceramics or combinations between these groups) used to fabricate gas sensors based on graphene and carbon nanotubes that are operated by conductance or resistance electrical, is realized. Next, different mathematical models that can be used to simulate gas sensors based on these materials are presented. In the third part, the impact of the graphene and carbon nanotubes on gas sensors is exemplified with technical advances achieved until now. Finally, it is provided a prospective analysis on the role of the gas sensors based on carbon nanomaterials in the next decades.

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A Review of Carbon Nanotubes-Based Gas Sensors

Journal of Sensors ◽

10.1155/2009/493904 ◽

2009 ◽

Vol 2009 ◽

pp. 1-24 ◽

Cited By ~ 255

Author(s):

Yun Wang ◽

John T. W. Yeow

Keyword(s):

Carbon Nanotubes ◽

Gas Sensors ◽

Gas Sensing ◽

Low Cost ◽

High Surface ◽

Hollow Structure ◽

Volume Ratio ◽

Fast Response ◽

Sensing Technology ◽

Structure Of Nanomaterials

Gas sensors have attracted intensive research interest due to the demand of sensitive, fast response, and stable sensors for industry, environmental monitoring, biomedicine, and so forth. The development of nanotechnology has created huge potential to build highly sensitive, low cost, portable sensors with low power consumption. The extremely high surface-to-volume ratio and hollow structure of nanomaterials is ideal for the adsorption of gas molecules. Particularly, the advent of carbon nanotubes (CNTs) has fuelled the inventions of gas sensors that exploit CNTs' unique geometry, morphology, and material properties. Upon exposure to certain gases, the changes in CNTs' properties can be detected by various methods. Therefore, CNTs-based gas sensors and their mechanisms have been widely studied recently. In this paper, a broad but yet in-depth survey of current CNTs-based gas sensing technology is presented. Both experimental works and theoretical simulations are reviewed. The design, fabrication, and the sensing mechanisms of the CNTs-based gas sensors are discussed. The challenges and perspectives of the research are also addressed in this review.

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Fully Transparent Gas Sensor Based on Carbon Nanotubes

Sensors ◽

10.3390/s19204591 ◽

2019 ◽

Vol 19 (20) ◽

pp. 4591 ◽

Cited By ~ 1

Author(s):

Florin C. Loghin ◽

Aniello Falco ◽

Jose F. Salmeron ◽

Paolo Lugli ◽

Alaa Abdellah ◽

...

Keyword(s):

Carbon Nanotubes ◽

Gas Sensor ◽

Active Layer ◽

Gas Sensors ◽

Spray Deposition ◽

Reference Electrode ◽

Gold Electrodes ◽

Integrated Sensors ◽

Reference Sensor ◽

Higher Sensitivity

In this paper, we demonstrate the feasibility of realization of transparent gas sensors based on carbon nanotubes (CNTs). Both sensing layer and electrodes consist of CNTs deposited by spray deposition. The transparent sensor—with a transmittance higher than 60% in both sensing layer and electrodes—is characterized towards NH3 and CO2 and compared with a reference sensor with the same active layer but evaporated Au electrodes. In particular, the sensitivity towards NH3 is virtually identical for both reference and transparent sensors, whereas the transparent device exhibits higher sensitivity to CO2 than the reference electrode. The effect of the spacing among consecutive electrodes is also studied, demonstrating that a wider spacing in fully CNT based sensors results in a higher sensitivity because of the higher sensing resistance, whereas this effect was not observed in gold electrodes, as their resistance can be neglected with respect to the resistance of the CNT sensing layer. Overall, the transparent sensors show performance comparable—if not superior—to the traditionally realized ones, opening the way for seamlessly integrated sensors, which do not compromise on quality.

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