Highly Sensitive and Stable NO<sub>2</sub> Gas Sensors Based on SWNTs With Exceptional Recovery Time

Chauhan, Sandeep Singh; Kumar, Deepak; Chaturvedi, Poornendu; Rahman, Muneeb-Ur

doi:10.1109/jsen.2019.2937506

Cited by 10 publications

(3 citation statements)

References 45 publications

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“…The assembled CNTs respond differently to the target material based on their distribution form. Aligned CNTs showed a faster response than randomly distributed CNTs [222]. Sensors mostly use mt-SWCNTs or MWCNTs due to their stability and fast response compared with sc-SWCNTs.…”

Section: Sensor Devicesmentioning

confidence: 99%

Dielectrophoretic alignment of carbon nanotubes: theory, applications, and future

2023

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Carbon nanotubes (CNTs) are nominated to be the successor of several semiconductors and metals due to their unique physical and chemical properties. It has been concerning that the anisotropic and low controllability of CNTs impedes their adoption in commercial applications. Dielectrophoresis (DEP) is known as the electrokinetics motion of polarizable nanoparticles under the influence of non-uniform electric fields. The uniqueness of this phenomenon allows DEP to be employed as a novel method to align, assemble, separate, and manipulate CNTs suspended in liquid mediums. This article begins with a brief overview of CNT structure and production, with the emphasize on their electrical properties and response to electric fields. The DEP phenomenon as a CNT alignment method is demonstrated and graphically discussed, along with its theory, procedure, and parameters. We also discussed the side forces that arise in DEP systems and how they negatively or positively affect the CNT alignment. The article concludes with a brief review of CNT-based devices fabricated using DEP, as well as the method’s limitations and future prospects. 

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Section: Sensor Devicesmentioning

confidence: 99%

Dielectrophoretic alignment of carbon nanotubes: theory, applications, and future

2023

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“…Moreover, they also proposed the possibility of using SWNT-based sensors to detect NO 2 , CO 2 , NH 3 , H 2 , CO, H 2 S, etc . Chauhan and his co-workers also fabricated highly sensitive and stable SWNT-based gas sensors successfully for the detection of stable NO 2 with exceptional recovery time …”

Section: Introductionmentioning

confidence: 99%

Density Functional Theory Study of Adsorption and Selection Behavior of Harmful Gas Molecules on the Surface of SWNTs: Implications for Gas Sensing

Tang,

Zhao,

Liang

et al. 2023

ACS Appl. Nano Mater.

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To explore the adsorption and selection behavior of harmful gas molecules on the surface of single-walled nanotubes (SWNTs) within field-effect transistors (FETs), NO 2 , SO 2 , NO, CO 2 , H 2 S, and NH 3 adsorption effects on the electronic character of SWNTs (three different armchair SWNTs with indexes (6,6), (9,9), and (10,10)) were explored theoretically by density functional theory (DFT) calculations in this work. Two factors determining the sensing mechanism of real devices, namely, the electrostatic gate modulation caused by internal carrier mobility within SWNT networks and the interfacial Schottky barrier effects caused by the work function changes of SWNTs, will be examined. Calculated results show that the adsorption process of gas molecules on the surface of SWNTs is exothermic and energetically favored. From the work function results, it is predicted that the interfacial Schottky barrier of the contact between SWNTs and neighboring materials must be affected significantly upon adsorption of different gas molecules, which may lead to distinct electrical resistance changes of SWNT-FETs. Moreover, it is observed that electron density distribution of SWNTs is increased by NH 3 adsorption while it is decreased by other gas adsorptions. It means that the internal carrier mobility of SWNTs must be increased by NH 3 adsorption while it must be decreased by other gas adsorptions with a trend NO 2 > SO 2 > NO > CO 2 > H 2 S. Therefore, it is confirmed that SWNTs should be highly electrically sensitive and responsive to harmful gas molecules, which is favorable for their application in gas sensor areas.

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“…Dielectrophoresis (DEP) has gained attention as an assembly and alignment method for CNTs due to its simple setup and high controllability in placing the CNTs at the desired location [8]. It is important to assemble CNTs across electrodes in an aligned form because CNTs show their best conductivity performance when they are aligned, which is highly desirable in CNT-based transistors, sensors, and biosensors [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Assembly of long carbon nanotube bridges across transparent electrodes using novel thickness‐controlled dielectrophoresis

et al. 2021

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The assembly of carbon nanotubes (CNTs) across planner electrodes using dielectrophoresis (DEP) is one of the standard methods used to fabricate CNT-based devices such as sensors. The medium drag velocity caused by electrokinetic phenomena such as electrothermal and electroosmotic might drive CNTs away from the deposition area. This problem becomes critical at large-scale electrode structures due to the high attenuation of the DEP force. Herein, we simulated and experimentally validated a novel DEP setup that uses a top glass cover to minimize the medium drag velocity. The simulation results showed that the drag velocity can be reduced by 2-3 orders of magnitude compared with the basic DEP setup. The simulation also showed that the optimum channel height to result in a significant drag velocity reduction was between 100 μm and 240 μm. We experimentally report, for the first time, the assembly and alignment of CNT bridges across indium tin oxide (ITO) electrodes with spacing up to 125 μm. We also derived an equation to optimize the CNT's concentration in suspensions based on the electrode gap width and channel height. The deposition of long CNTs across ITO electrodes has potential use in transparent electronics and microfluidic systems.

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Highly Sensitive and Stable NO₂ Gas Sensors Based on SWNTs With Exceptional Recovery Time

Cited by 10 publications

References 45 publications

Dielectrophoretic alignment of carbon nanotubes: theory, applications, and future

Dielectrophoretic alignment of carbon nanotubes: theory, applications, and future

Density Functional Theory Study of Adsorption and Selection Behavior of Harmful Gas Molecules on the Surface of SWNTs: Implications for Gas Sensing

Assembly of long carbon nanotube bridges across transparent electrodes using novel thickness‐controlled dielectrophoresis

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Highly Sensitive and Stable NO2 Gas Sensors Based on SWNTs With Exceptional Recovery Time

Cited by 10 publications

References 45 publications

Dielectrophoretic alignment of carbon nanotubes: theory, applications, and future

Dielectrophoretic alignment of carbon nanotubes: theory, applications, and future

Density Functional Theory Study of Adsorption and Selection Behavior of Harmful Gas Molecules on the Surface of SWNTs: Implications for Gas Sensing

Assembly of long carbon nanotube bridges across transparent electrodes using novel thickness‐controlled dielectrophoresis

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Highly Sensitive and Stable NO₂ Gas Sensors Based on SWNTs With Exceptional Recovery Time