scholarly journals Fully Transparent Gas Sensor Based on Carbon Nanotubes

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4591 ◽  
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.

Sensing Properties of Sub-ppm Level NO2 Gas Sensor Based on YSZ and WO3 Sensing Electrode

2014 ◽  
Vol 633 ◽  
pp. 512-515
Author(s):  
Xia Sun ◽  
Guo Liang Zhou ◽  
Chuan Long Pan ◽  
Cheng Zhang ◽  
Tao Feng
Keyword(s):  
Gas Sensor ◽  
Gas Sensors ◽  
Electrode Surface ◽  
Reference Electrode ◽  
Mixed Potential ◽  
Response Signal ◽  
Preparation Methods ◽  
Sensing Properties ◽  
Sensitive Electrode ◽  
Ppm Level

In this paper, the gas sensors using WO3 as sensitive electrode, Pt mixed potential as the reference electrode was researched. The structures and preparation methods of the sensors were introduced. Besides, the sensitive materials, the electrode surface and the section morphologies were characterized by means of SEM and EDS. Furthermore, the sensing properties of the as-fabricated sensors were examined under different NOX concentrations and temperatures (500°C, 550°C and 600°C). The results revealed that the response signal become smaller with the temperature increasing, and stronger with the increasing of the NO2 concentration.

Solution-Based Fabrication of Carbon Nanotube Gas Sensor by Using Dielectrophoresis and Spin-Column Chromatography

2013 ◽  
Vol 699 ◽  
pp. 915-920
Author(s):  
Hideaki Watanabe ◽  
Hiroki Komure ◽  
Michihiko Nakano ◽  
Junya Suehiro
Keyword(s):  
Carbon Nanotubes ◽  
Electronic Structure ◽  
Carbon Nanotube ◽  
Gas Sensor ◽  
Column Chromatography ◽  
Gas Sensors ◽  
Single Walled Carbon Nanotubes ◽  
Sensor Response ◽  
Spin Column ◽  
Walled Carbon Nanotubes

Single-walled carbon nanotubes (SWCNTs) gas sensor has attracted a great deal of attention because of their remarkable properties. The sensor response is attribute to the semiconducting CNT whose electronic properties depend on its chirality. The authors have previously found that the sensor response increased by using separated semiconducting SWCNTs from a mixture with metallic one. Since the electronic structure (metallic or semiconducting) of CNTs is governed by their chirality, a chirality-selective fabrication of CNT gas sensor is essential to improve their performance. In this study, we proposed chirality-based separation of semiconducting SWCNTs by using spin-column chromatography. Pristine CNT suspension was separated into three fractions that had different chiralities of semiconducting SWCNTs. Separated semiconducting CNTs of each fraction were used for fabrication of three CNT gas sensors by dielectrophoresis. Comparison of these sensor responses to NO2 revealed that sensor response depended on the chirality.

scholarly journals A computational study of a chemical gas sensor utilizing Pd–rGO composite on SnO2 thin film for the detection of NOx

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
S. Akshya ◽  
A. Vimala Juliet
Keyword(s):  
Thin Film ◽  
Nitrogen Oxides ◽  
Gas Sensor ◽  
Active Layer ◽  
Gas Sensors ◽  
Computational Study ◽  
Active Material ◽  
Sno2 Thin Film ◽  
Active Materials ◽  
Active Layers

AbstractIn this paper we discussed, nitrogen oxides gas sensors are designed and simulated using the MEMS-based tool of COMSOL Multiphysics software. Pd–rGO composite films were designed and their NOx sensing characteristics were investigated in this study by comparing with/without active layers. Transition metal SnO2 deals with four different active materials i.e., Pure SnO2, SnO2–Pd, SnO2–rGO, and SnO2–Pd/rGO film was controlled by altering the active materials during the active layer deposition. The deposition of Pd/rGO active material is integrated into the SnO2 thin film. The response of the nanocomposite materials on the NOx gas sensor at a low temperature below 100 °C was significantly improved. Moreover, we investigate the optimization from different active layer response for NOx by applying power in watt and milliwatt to the interdigitated electrode on the Sn substrate. The determination is tense to finalize the suitable materials that to detect more response for nitrogen oxides i.e., Pd/rGO layer shows better performance when compared with other active layers for the sensing of nitrogen oxides is in proportion to the power in the range of 0.6–4.8 W at (1–8) Voltage range. This advanced research will enable a new class of portable NOx gas sensors to be constructed with millimeter size and microwatt power.

Fabrication of TiO2 Nanotube Arrays and Their Application to a Gas Sensor

2015 ◽  
Vol 15 (10) ◽  
pp. 8161-8165 ◽  
Author(s):  
Wan-Tae Kim ◽  
In-Ho Kim ◽  
Won-Youl Choi
Keyword(s):  
Gas Sensor ◽  
Active Layer ◽  
Metal Oxide Semiconductor ◽  
Oxide Semiconductor ◽  
Gas Detection ◽  
Nanotube Arrays ◽  
Adhesion Layer ◽  
Gas Concentration ◽  
Open Window ◽  
Higher Sensitivity

To improve sensing performance, the metal oxide semiconductor (MOS) gas sensor needs to have amuch bigger specific surface area in the active layer, lower power and higher sensitivity. TiO2 nanotube arrays were used for the active layer of a MOS gas sensor because they are chemically stable and electrically semi conductive. To obtain clean, open window nanotubes, two-step anodic oxidation was conducted. The diameter of the window and length of the nanotubes were 60 nm and 5.5 μm, respectively. TiO2 nanotube arrays were transplanted by the SnO2 adhesion layer. The SnO2 adhesion layer had a nanoparticle diameter of 30 nm and a thickness of 4 μm. The sensitivity increased with the CO gas concentration and was 0.061 at 300 ppm. The response was very quick. A power consumption of 80 mW was measured with an effective gas detection performance.

Metal-oxide based ammonia gas sensors: A review

2020 ◽  
Vol 10 ◽  
Author(s):  
Priya Gupta ◽  
Savita Maurya ◽  
Narendra Kumar Pandey ◽  
Vernica Verma
Keyword(s):  
Metal Oxide ◽  
Metal Oxides ◽  
Gas Sensor ◽  
Gas Sensors ◽  
Review Paper ◽  
Gas Sensing ◽  
Gas Sensitivity ◽  
Ammonia Gas ◽  
Ammonia Sensing ◽  
Ammonia Gas Sensors

: This review paper encompasses a study of metal-oxide and their composite based gas sensors used for the detection of ammonia (NH3) gas. Metal-oxide has come into view as an encouraging choice in the gas sensor industry. This review paper focuses on the ammonia sensing principle of the metal oxides. It also includes various approaches adopted for increasing the gas sensitivity of metal-oxide sensors. Increasing the sensitivity of the ammonia gas sensor includes size effects and doping by metal or other metal oxides which will change the microstructure and morphology of the metal oxides. Different parameters that affect the performances like sensitivity, stability, and selectivity of gas sensors are discussed in this paper. Performances of the most operated metal oxides with strengths and limitations in ammonia gas sensing application are reviewed. The challenges for the development of high sensitive and selective ammonia gas sensor are also discussed.

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 Field Study of Metal Oxide Semiconductor Gas Sensors in Temperature Cycled Operation for Selective VOC Monitoring in Indoor Air

Atmosphere ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 647
Author(s):  
Tobias Baur ◽  
Johannes Amann ◽  
Caroline Schultealbert ◽  
Andreas Schütze
Keyword(s):  
Air Quality ◽  
Metal Oxide ◽  
Gas Sensor ◽  
Gas Sensors ◽  
Indoor Air ◽  
Ambient Air ◽  
Quantitative Agreement ◽  
Metal Oxide Semiconductor ◽  
Oxide Semiconductor ◽  
High Temporal Resolution

More and more metal oxide semiconductor (MOS) gas sensors with digital interfaces are entering the market for indoor air quality (IAQ) monitoring. These sensors are intended to measure volatile organic compounds (VOCs) in indoor air, an important air quality factor. However, their standard operating mode often does not make full use of their true capabilities. More sophisticated operation modes, extensive calibration and advanced data evaluation can significantly improve VOC measurements and, furthermore, achieve selective measurements of single gases or at least types of VOCs. This study provides an overview of the potential and limits of MOS gas sensors for IAQ monitoring using temperature cycled operation (TCO), calibration with randomized exposure and data-based models trained with advanced machine learning. After lab calibration, a commercial digital gas sensor with four different gas-sensitive layers was tested in the field over several weeks. In addition to monitoring normal ambient air, release tests were performed with compounds that were included in the lab calibration, but also with additional VOCs. The tests were accompanied by different analytical systems (GC-MS with Tenax sampling, mobile GC-PID and GC-RCP). The results show quantitative agreement between analytical systems and the MOS gas sensor system. The study shows that MOS sensors are highly suitable for determining the overall VOC concentrations with high temporal resolution and, with some restrictions, also for selective measurements of individual components.

High performance gas sensors with dual response based on organic ambipolar transistors

2021 ◽  
Author(s):  
Xu Zhou ◽  
Zi Wang ◽  
Ruxin Song ◽  
Yadan Zhang ◽  
Lunan Zhu ◽  
...  
Keyword(s):  
Gas Sensor ◽  
Gas Sensors ◽  
High Performance ◽  
Dual Response

A high performance organic ambipolar transistor-based gas sensor was constructed. It demonstrates dual response features and good selectivity.

scholarly journals Decoration of CuO NWs Gas Sensor with ZnO NPs for Improving NO2 Sensing Characteristics

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 2103 ◽  
Author(s):  
Tae-Hee Han ◽  
So-Young Bak ◽  
Sangwoo Kim ◽  
Se Hyeong Lee ◽  
Ye-Ji Han ◽  
...  
Keyword(s):  
Gas Sensor ◽  
Gas Sensors ◽  
Sol Gel ◽  
Oxide Semiconductor ◽  
Zno Nps ◽  
X Ray ◽  
Semiconductor Gas Sensor ◽  
Initial Resistance ◽  
P Type ◽  
Sensing Characteristics

This paper introduces a method for improving the sensitivity to NO2 gas of a p-type metal oxide semiconductor gas sensor. The gas sensor was fabricated using CuO nanowires (NWs) grown through thermal oxidation and decorated with ZnO nanoparticles (NPs) using a sol-gel method. The CuO gas sensor with a ZnO heterojunction exhibited better sensitivity to NO2 gas than the pristine CuO gas sensor. The heterojunction in CuO/ZnO gas sensors caused a decrease in the width of the hole accumulation layer (HAL) and an increase in the initial resistance. The possibility to influence the width of the HAL helped improve the NO2 sensing characteristics of the gas sensor. The growth morphology, atomic composition, and crystal structure of the gas sensors were analyzed using field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy, and X-ray diffraction, respectively.

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