| 1. |
- Nguyen, Xuan Thai, et al.
(författare)
-
Gas sensor array based on tin oxide nano structure for volatile organic compounds detection
- 2020
-
Ingår i: Vietnam Journal of Science and Technology. - : Vietnam Academy of Science and Technology. - 2525-2518. ; 58:2, s. 189-196
-
Tidskriftsartikel (refereegranskat)abstract
- The detection of volatile organic compounds (VOCs) is essential in practicalapplication in breath analysis. Thus, gas sensors based on metal oxide have been fabricated, butthey lacked selectivity. One approach to resolve this task is to use an array of highly sensitiveand selective sensors as an electronic nose. Here a gas sensor array based on Tin oxide nanostructurewith temperature modulation techniques was presented. A Platinum micro-heater isaccompanied with the array gas sensor. The gas sensor array was composed of five singlesensors, and that single sensor is located at different site from the micro heater and works atdifferent temperatures. The gas sensing properties of the gas array sensors were investigatedwith VOC gases such as Ethanol, Methanol, Iso-propanol, and Acetone as well as NH3, H2, andH2S. We also confirm the good selectivity of the array sensor for Ethanol, Methanol, Isopropanol,Acetone, NH3, H2, and H2S by using radar graphic method.
|
|
| 2. |
- Thai, Nguyen Xuan, et al.
(författare)
-
Prototype edge-grown nanowire sensor array for the real-time monitoring and classification of multiple gases
- 2020
-
Ingår i: JOURNAL OF SCIENCE-ADVANCED MATERIALS AND DEVICES. - : VIETNAM NATL UNIV. - 2468-2284 .- 2468-2179. ; 5:3, s. 409-416
-
Tidskriftsartikel (refereegranskat)abstract
- The monitoring and classification of different gases using a single resistive semiconductor sensor are challenging because of the similar response characteristics. An array of separated sensors can be used as an electronic nose, but such arrays have a bulky structure and complex fabrication processes. Herein, we easily fabricated a gas-sensor array based on edge-grown SnO2 nanowires for the real-time monitoring and classification of multiple gases. The array comprised four sensors and was designed on a glass substrate. SnO2 nanowires were grown on-chip from the edge of electrodes, made contact together, and acted as sensing elements. This method was advantageous over the post-synthesis technique because the SnO2 nanowires were directly grown from the edge of the electrodes rather than on the surface. Accordingly, damage to the electrode was avoided by alloying Sn with Pt at a high growth temperature. The sensing characteristics of the sensor array were further examined for different gases, including methanol, isopropanol, ethanol, ammonia, hydrogen sulphide and hydrogen. Radar plots were used to improve the selective detection of different gases and enable effective classification. (C) 2020 The Authors. Publishing services by Elsevier B.V. on behalf of Vietnam National University, Hanoi.
|
|
| 3. |
- Thai, Nguyen Xuan, et al.
(författare)
-
Realization of a portable H2S sensing instrument based on SnO2 nanowires
- 2020
-
Ingår i: Journal of Science: Advanced Materials and Devices. - : Elsevier BV. - 2468-2284 .- 2468-2179. ; 5:1, s. 40-47
-
Tidskriftsartikel (refereegranskat)abstract
- Monitoring of toxic gas in air is important because air pollution, especially in developing countries, has rapidly become severe. The high cost of installation and maintenance of a stationary analysis system by using methods such as gas chromatography limits its applications. Low-power, portable devices with relatively low-cost gas sensors are effective for mapping pollution levels in real-time in urban areas and in other living environmentts. Herein, the realization of a portable H2S sensing instrument based on SnO2 nanowires is reported. The sensor chip was prepared by the on-chip growth of SnO2 nanowires directly from the edges of Pt electrodes. The electronic system and software for signal acquisition, data processing, data storage, and output of the instrument were developed. A prototype for zero series of the instrument was also realized. The instrument is capable of monitoring H2S gas in air at ppm level and in biogas production with satisfation.
|
|
| 4. |
- Thai, Nguyen Xuan, et al.
(författare)
-
Multi gas sensors using one nanomaterial, temperature gradient, and machine learning algorithms for discrimination of gases and their concentration
- 2020
-
Ingår i: Analytica Chimica Acta. - : ELSEVIER. - 0003-2670 .- 1873-4324. ; 1124, s. 85-93
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, four identical micro sensors on the same chip with noble metal decorated tin oxide nanowires as gas sensing material were located at different distances from an integrated heater to work at different temperatures. Their responses are combined in highly informative 4D points that can qualitatively (gas recognition) and quantitatively (concentration estimate) discriminate all the tested gases. Two identical chips were fabricated with tin oxide (SnO2) nanowires decorated with different metal nanoparticles: one decorated with Ag nanoparticles and one with Pt nanoparticles. Support Vector Machine was used as the "brain" of the sensing system. The results show that the systems using these multisensor chips were capable of achieving perfect classification (100%) and good estimation of the concentration of tested gases (errors in the range 8-28%). The Ag decorated sensors did not have a preferential gas, while Pt decorated sensors showed a lower error towards acetone, hydrogen and ammonia. Combination of the two sensor chips improved the overall estimation of gas concentrations, but the individual sensor chips were better for some specific target gases. (C) 2020 Elsevier B.V. All rights reserved.
|
|
| 5. |
- Luu, Chinh, et al.
(författare)
-
Framework of Spatial Flood Risk Assessment for a Case Study in Quang Binh Province, Vietnam
- 2020
-
Ingår i: Sustainability. - Switzerland : MDPI. - 2071-1050. ; 12:7, s. 1-17
-
Tidskriftsartikel (refereegranskat)abstract
- Vietnam has been extensively affected by floods, suffering heavy losses in human life andproperty. While the Vietnamese government has focused on structural measures of flood defence such as levees and early warning systems, the country still lacks flood risk assessment methodologies and frameworks at local and national levels. In response to this gap, this study developed a flood risk assessment framework that uses historical flood mark data and a high- resolution digital elevation model to create an inundation map, then combined this map with exposure and vulnerability data to develop a holistic flood risk assessment map. The case study is the October 2010 flood event in Quang Binh province, which caused 74 deaths, 210 injuries, 188,628 flooded properties, 9019 ha of submerged and damaged agricultural land, and widespread damages to canals, levees, and roads. The final flood risk map showed a total inundation area of 64348 ha, in which 8.3% area of low risk, 16.3% area of medium risk, 12.0% area of high risk, 37.1% area of very high risk, and 26.2% area of extremely high risk. The holistic flood risk assessment map of QuangBinh province is a valuable tool and source for flood preparedness activities at the local scale.
|
|
