scholarly journals Ethanol Gas Sensitivity Sensor Based on Roughened POF Taper of Modified Polypyrrole Films

Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 989 ◽  
Author(s):  
Wenyi Liu ◽  
Yanjun Hu ◽  
Yulong Hou
Keyword(s):  
Low Cost ◽  
High Sensitivity ◽  
Chemical Oxidation ◽  
Gas Sensitivity ◽  
Polypyrrole Films ◽  
Shape Structure ◽  
Recovery Times ◽  
Bending Radius ◽  
Response And Recovery ◽  
Gas Response

The three polypyrrole (PPy) films with different mixture ratios, namely PPy1, PPy2, and PPy3, were synthesized by chemical oxidation with pyrrole and ferric chloride (FeCl3). The roughened plastic optical fiber (POF) taper assembled PPy films (POF-PPy1, POF-PPy2, and POF-PPy3) were facilely prepared and bent U shape structure for testing ethanol gas at room temperature. The morphologies of the PPy films and the roughened POF taper were studied using electron microscopy. The effect of the three PPy films on the gas response was investigated and the results showed that the POF-PPy2 exhibited a high sensitivity of 5.08 × 10−5 dB/ppm. The detection limit of the sensor was 140 ppm and its response and recovery times were 5 s and 8 s, respectively. The results also showed that as the bending radius decreased, the response and recovery times gradually shortened, while the output power increased. In addition, the proposed sensor has advantages of a low cost and simple structure.

scholarly journals Tin Disulfide-Coated Microfiber for Humidity Sensing with Fast Response and High Sensitivity

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 648
Author(s):  
Aijie Liang ◽  
Jingyuan Ming ◽  
Wenguo Zhu ◽  
Heyuan Guan ◽  
Xinyang Han ◽  
...  
Keyword(s):  
Humidity Sensor ◽  
Small Diameter ◽  
High Sensitivity ◽  
Large Change ◽  
Small Variation ◽  
Response Speed ◽  
Fast Response ◽  
Tin Disulfide ◽  
Recovery Times ◽  
Response And Recovery

Breath monitoring is significant in assessing human body conditions, such as cardiac and pulmonary symptoms. Optical fiber-based sensors have attracted much attention since they are immune to electromagnetic radiation, thus are safe for patients. Here, a microfiber (MF) humidity sensor is fabricated by coating tin disulfide (SnS2) nanosheets onto the surface of MF. The small diameter (~8 μm) and the long length (~5 mm) of the MF promise strong interaction between guiding light and SnS2. Thus, a small variation in the relative humidity (RH) will lead to a large change in optical transmitted power. A high RH sensitivity of 0.57 dB/%RH is therefore achieved. The response and recovery times are estimated to be 0.08 and 0.28 s, respectively. The high sensitivity and fast response speed enable our SnS2-MF sensor to monitor human breath in real time.

scholarly journals Gas-sensing features of nanostructured tellurium thin films

2020 ◽  
Vol 11 ◽  
pp. 1010-1018
Author(s):  
Dumitru Tsiulyanu
Keyword(s):  
Thin Films ◽  
Gas Sensing ◽  
Operating Temperature ◽  
Active Surface ◽  
Active Surface Area ◽  
Gas Sensitivity ◽  
Nanocrystalline And Amorphous ◽  
Recovery Times ◽  
Order Of Magnitude ◽  
Response And Recovery

Nanocrystalline and amorphous nanostructured tellurium (Te) thin films were grown and their gas-sensing properties were investigated at different operating temperatures with respect to scanning electron microscopy and X-ray diffraction analyses. It was shown that both types of films interacted with nitrogen dioxide, which resulted in a decrease of electrical conductivity. The gas sensitivity, as well as the response and recovery times, differed between these two nanostructured films. It is worth mentioning that these properties also depend on the operating temperature and the applied gas concentration on the films. An increase in the operating temperature decreased not only the response and recovery times but also the gas sensitivity of the nanocrystalline films. This shortcoming could be solved by using the amorphous nanostructured Te films which, even at 22 °C, exhibited higher gas sensitivity and shorter response and recovery times by more than one order of magnitude in comparison to the nanocrystalline Te films. These results were interpreted in terms of an increase in disorder (amorphization), leading to an increase in the surface chemical activity of chalcogenides, as well as an increase in the active surface area due to substrate porosity.

Gas Sensing Properties of Porous ZnO Nano-Platelet Films

2007 ◽  
Vol 1035 ◽  
Author(s):  
Amandeep Saluja ◽  
Jie Pan ◽  
Lei Kerr ◽  
Eunjung Cho ◽  
Seth Hubbard
Keyword(s):  
Gas Flow ◽  
Room Temperature ◽  
Gas Sensing ◽  
Electrode Spacing ◽  
Porous Films ◽  
Gas Sensitivity ◽  
Gas Sensing Properties ◽  
Recovery Times ◽  
Response And Recovery ◽  
Carrier Gas Flow

AbstractIn this work, various ZnO nanostructures were synthesized and a detailed study on the effect of different process parameters such as temperature, carrier gas flow, inter-electrode spacing, gas concentration and material properties on gas sensitivity was conducted. Initial ZnO nanoparticles were prepared by a simple solution chemical process and characterized by Secondary Electron Microscopy (SEM) and Brunauer, Emmet and Teller (BET) Sorptometer to demonstrate the morphology and surface area respectively. Sensitivity of nano-platelets and porous films was measured for different concentrations of the analytes (H2, CO). High response was observed at room temperature for H2 gas with sensitivities in excess 80% for 60ppm and about 55% for 80ppm of H2 gas at room temperature were observed for the nano-platelets and the porous films respectively with short response and recovery times of about 200 seconds. The sensitivity of the nano-platelets to CO gas was also measured and found to be about near 90% for 80 ppm CO at operating temperatures of 200 °C.

Enhanced Gas Sensing of Tin Dioxide Based Sensor for Indoor Formaldehyde Application

2021 ◽  
Vol 16 (2) ◽  
pp. 337-342
Author(s):  
Gaoqi Zhang ◽  
Fan Zhang ◽  
Kaifang Wang ◽  
Shanyu Liu ◽  
Ying Wang ◽  
...  
Keyword(s):  
Gas Sensors ◽  
Tin Dioxide ◽  
Gas Sensing ◽  
Fast Response ◽  
Sensing Material ◽  
Gas Sensing Properties ◽  
Recovery Times ◽  
Response And Recovery ◽  
Formaldehyde Sensing ◽  
Gas Response

Indoor formaldehyde detection is of great important at present. Using efficient solvothermal method, nanosheet-constructed and nanorod-constructed hierarchical tin dioxide (SnO2) microspheres were successfully synthesized in this work and used for the gas sensing material for indoor formaldehyde application. The as-prepared two kinds of SnO2 gas sensing materials were applied to fabricate the gas sensors and formaldehyde gas sensing experiments were carried out. The HCHO gas sensing tests indicate that the gas response of the nanosheet-constructed SnO2 microspheres is about 1.7 times higher than that of the nanorod-constructed SnO2 microspheres. In addition, both of the two SnO2 based gas sensors show almost fast response and recovery time to HCHO gas. For the nanosheet-constructed microspheres, the response value is estimated to be 32.0 at 350 °C to 60 ppm formaldehyde gas, while the response and recovery times are 7 and 5 s, respectively. The simple and efficient preparation method and improved gas sensing properties show that the as-synthesized hierarchical SnO2 microsphere that is constructed by a large amount of nanosheets exhibits significant potential application for the indoor formaldehyde sensing.

scholarly journals High Sensitivity of Ammonia Sensor through 2D Black Phosphorus/Polyaniline Nanocomposite

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3026
Author(s):  
Zuquan Wu ◽  
Lei Liang ◽  
Shibu Zhu ◽  
Yifan Guo ◽  
Yao Yao ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Low Cost ◽  
Oxidative Polymerization ◽  
High Sensitivity ◽  
Fast Response ◽  
Experimental Result ◽  
Conjugation System ◽  
Detection Range ◽  
Sensing Material ◽  
Response And Recovery

Recently, as a two-dimensional (2D) material, black phosphorous (BP) has attracted more and more attention. However, few efforts have been made to investigate the BP/polyaniline (PANI) nanocomposite for ammonia (NH3) gas sensors. In this work, the BP/PANI nanocomposite as a novel sensing material for NH3 detection, has been synthesized via in situ chemical oxidative polymerization, which is then fabricated onto the interdigitated transducer (IDTs). The electrical properties of the BP/PANI thin film are studied in a large detection range from 1 to 4000 ppm, such as conduction mechanism, response, reproducibility, and selectivity. The experimental result indicates that the BP/PANI sensor shows higher sensitivity and larger detection range than that of PANI. The BP added into PANI, that may enlarge the specific surface area, obtain the special trough structure for gas channels, and form the p–π conjugation system and p–p isotype heterojunctions, which are beneficial to increase the response of BP/PANI to NH3 sensing. Meanwhile, in order to support the discussion result, the structure and morphology of the BP/PANI are respectively measured by Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV−vis), transmission electron microscopy (TEM), and field emissions scanning electron microscopy (SEM). Moreover, the sensor shows good reproducibility, and fast response and recovery behavior, on NH3 sensing. In addition, this route may offer the advantages of an NH3 sensor, which are of simple structure, low cost, easy to assemble, and operate at room temperature.

High sensitivity and fast response and recovery times in a ZnO nanorod array/p-Si self-powered ultraviolet detector

2012 ◽  
Vol 101 (26) ◽  
pp. 261108 ◽  
Author(s):  
J. J. Hassan ◽  
M. A. Mahdi ◽  
S. J. Kasim ◽  
Naser M. Ahmed ◽  
H. Abu Hassan ◽  
...  
Keyword(s):  
High Sensitivity ◽  
Nanorod Array ◽  
Fast Response ◽  
Zno Nanorod ◽  
Ultraviolet Detector ◽  
Recovery Times ◽  
Response And Recovery ◽  
Zno Nanorod Array ◽  
Self Powered

scholarly journals Fabrication of Cr2O3: ZnO Nanostructure Thin Film Prepared by PLD Technique as NH3 Gas Sensor

2021 ◽  
pp. 2176-2187
Author(s):  
S.M. AbdulKareem ◽  
M.H. Suhail ◽  
I. K. Adehmash
Keyword(s):  
Response Time ◽  
Operating Temperature ◽  
Average Crystallite Size ◽  
X Ray Diffraction ◽  
Gas Sensitivity ◽  
Force Microscopy ◽  
Zno Nanostructure ◽  
Atomic Force ◽  
Recovery Times ◽  
Response And Recovery

     Chromium oxide (Cr2O3) doped ZnO nanoparticles were prepared by pulsed laser deposition (PLD) technique at different concentration ratios (0, 3, 5, 7 and 9 wt %) of ZnO on glass substrate. The effects of ZnO dopant on the average crystallite size of the synthesized nanoparticles was examined By X-ray diffraction. The morphological features were detected using atomic force microscopy (AFM). The optical band gap value was observed to range between 2.78 to 2.50 eV by UV-Vis absorption spectroscopy, with longer wavelength shifted in comparison with that of the bulk Cr2O3 (~3eV). Gas sensitivity, response, and recovery times of the sensor in the presence of NH3 gas were studied and discussed. In the present work, we found that the sensitivity was increased upon increasing the concentration ratio from 3 to 5%wt of ZnO, whereas it was decreased again over that value. Also, we found that the sensitivity was increased when increasing operating temperature, while the response time was decreased. The optimum concentrations ratio for NH3 gas sensitivity at 5%wt ZnO revealed sensitivity of 66.67% and response time of 14s at operating temperature of 300oC and 700mJ PLD energy.

A Flexible Humidity Sensor Based on Co3O4 Nanoneedles with High Sensitivity and Quick Response

2020 ◽  
Vol 15 (7) ◽  
pp. 870-874
Author(s):  
Qi Qi ◽  
Qi Wang ◽  
Nanliu Liu ◽  
Xiaoping Zheng ◽  
Xiongjie Ding ◽  
...  
Keyword(s):  
Humidity Sensor ◽  
High Sensitivity ◽  
Current Sensor ◽  
Quick Response ◽  
Bending Tests ◽  
Humidity Sensing ◽  
Recovery Times ◽  
Response And Recovery ◽  
Sensing Performance ◽  
Semilogarithmic Scale

A flexible humidity sensor has been realized based on Co3O4 nanoneedles via a deposition technique. High humidity sensing and excellent flexible properties are observed in the tests. The impedance of the as-prepared sensor decreases by nearly three orders of magnitude with increasing relative humidity (RH) from 11% to 95% on a semilogarithmic scale. The response and recovery times are about 3 and 6 s respectively. The maximum hysteresis is less than 4% under 80% RH. No obvious changes for the sensing performance can be obtained after 100 bending/extending cycles and bending tests. These performances make the current sensor a good candidate for flexible humidity detection.

scholarly journals Effect of Pd and Au Sensitization of Bath Deposited Flowerlike TiO2Thin Films on CO Sensing and Photocatalytic Properties

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Ashok K. Singh ◽  
S. B. Patil ◽  
Umesh T. Nakate ◽  
K. V. Gurav
Keyword(s):  
Thin Films ◽  
Gas Sensing ◽  
Anatase Phase ◽  
Xrd Analysis ◽  
Gas Sensitivity ◽  
Recovery Times ◽  
Response And Recovery ◽  
Cbd Method ◽  
Effect Of Pd ◽  
Degradation Properties

TiO2thin films having flower structure with nanopetals are deposited by chemical bath deposition (CBD) method. Deposited TiO2films are formed in pure anatase phase as confirmed by X-ray diffraction (XRD) analysis. Deposited films are used for detection of environmental hazardous carbon monoxide (CO) gas and photocatalytic (PC) degradation of malachite green (MG) dye. Effect of Pd and Au catalysts sensitization on gas sensing as well as PC degradation properties is investigated. The use of catalyst led to enhancement in the gas sensitivity and reduction in the operating temperature as well as response and recovery times. The Au sensitized film showed better CO sensing performance and PC efficiency in comparison to unsensitized and Pd sensitized TiO2thin films. For Au sensitized film, gas sensitivity, response time, and recovery time are found to be 32% (14% for TiO2), 80 s, and 100 s, respectively, and PC efficiency is found to be 26.6% (16.9% for TiO2).

scholarly journals Study of Two Vanadium Based Materials as Working Electrode for Developing A Selective Mixed-Potential Ammonia Sensor

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 770
Author(s):  
Gita Nematbakhsh Abkenar ◽  
Jean-Paul Viricelle ◽  
Mathilde Rieu ◽  
Philippe Breuil
Keyword(s):  
Reference Electrode ◽  
High Sensitivity ◽  
Fast Response ◽  
Mixed Potential ◽  
Ammonia Sensor ◽  
Ammonia Gas ◽  
Recovery Times ◽  
Response And Recovery ◽  
Increasing Temperature ◽  
Ammonia Gas Sensors

Mixed potential ammonia gas sensors were fabricated by using two sensing materials of Ni3V2O8 and Au-V2O5 as working electrodes, YSZ as electrolyte and platinum as reference electrode. The results have shown that the Ni3V2O8 sensors show cross-sensitivity toward NO gas. However, Au-V2O5 working electrodes displayed a high sensitivity to NH3 as well as fast response and recovery times at high temperatures. Furthermore, the results indicate that the selectivity of Au-V2O5 sensors increases by increasing temperature.

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