scholarly journals SnO2-TiO2 and SnO2-MoO3 Based Composite Gas Sensors to Develop an E-nose for Peruvian Pisco Varieties Differentiation

2022 ◽  
Author(s):  
Fabiola Bravo-Hualpa ◽  
Jorge Nelson Trevejo-Pinedo ◽  
Karinna Visurraga ◽  
Angela Pinedo ◽  
Kevin Acuna-Condori ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Gas Sensors ◽  
Sensor Response ◽  
Simple System ◽  
Alcoholic Drink ◽  
Weight Composition ◽  
Response Profile ◽  
Composition Ratios ◽  
Over Time

Abstract There is great interest in the development of a simple system that could identify adulteration or counterfeiting of Peruvian Pisco (a grape-based alcoholic drink). In this study, sensors based on SnO2-TiO2 and SnO2-MoO3 composites with different weight composition ratios were synthesized and characterized. These sensors were tested with aqueous solutions of EtOH/MetOH and Pisco samples of Italia and Quebranta varieties in order to explore their capacity to identify variations in these beverages. The response profile of the most sensitive sensors showed an enhanced response to alcoholic samples with greater content of ethanol up to a concentration of 45%v/v, while the increased content of methanol in the range of 0.1 to 0.3 % v/v diminished the intensity of the sensor response. Differences in the composition of methanol and ethanol in the Pisco varieties studied (Italia and Quebranta) were correlated to the capacity of the composite-based sensors to differentiate them with greater performance. Sensors based on SnO2-TiO2-1/2 composites showed greater reproducibility of their response profile over time in comparison to SnO2-TiO2-1/1 and SnO2-MoO3 composites. The PCA showed that composite sensors were able to differentiate Pisco samples according to their variety.

scholarly journals Short-Time Fourier Transform and Decision Tree-Based Pattern Recognition for Gas Identification Using Temperature Modulated Microhotplate Gas Sensors

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Aixiang He ◽  
Jun Yu ◽  
Guangfen Wei ◽  
Yi Chen ◽  
Hao Wu ◽  
...  
Keyword(s):  
Pattern Recognition ◽  
Fourier Transform ◽  
Decision Tree ◽  
Gas Sensors ◽  
Operating Temperature ◽  
Ambient Air ◽  
Sensor Response ◽  
Short Time Fourier Transform ◽  
Short Time ◽  
Different Gases

Because the sensor response is dependent on its operating temperature, modulated temperature operation is usually applied in gas sensors for the identification of different gases. In this paper, the modulated operating temperature of microhotplate gas sensors combined with a feature extraction method based on Short-Time Fourier Transform (STFT) is introduced. Because the gas concentration in the ambient air usually has high fluctuation, STFT is applied to extract transient features from time-frequency domain, and the relationship between the STFT spectrum and sensor response is further explored. Because of the low thermal time constant, the sufficient discriminatory information of different gases is preserved in the envelope of the response curve. Feature information tends to be contained in the lower frequencies, but not at higher frequencies. Therefore, features are extracted from the STFT amplitude values at the frequencies ranging from 0 Hz to the fundamental frequency to accomplish the identification task. These lower frequency features are extracted and further processed by decision tree-based pattern recognition. The proposed method shows high classification capability by the analysis of different concentration of carbon monoxide, methane, and ethanol.

Synthesis, Structural and Gas Sensing Characterization of W-Doped SnO2 Nanostructures

2017 ◽  
Vol 381 ◽  
pp. 15-19 ◽  
Author(s):  
Mukesh Chander Bhatnagar ◽  
Anima Johari
Keyword(s):  
Low Temperature ◽  
Gas Sensors ◽  
Gas Sensing ◽  
Operating Temperature ◽  
Environmental Pollutants ◽  
Sensor Response ◽  
Gas Content ◽  
Temperature Sensitive ◽  
Oxide Material ◽  
Industry Waste

Tin oxide material has been extensively used for gas sensing application. Due to high operating temperature of metal oxide gas sensors, around 600 K and long term instability, research has been carried out to improve the material properties and reducing operating temperature. nanostructure materials have shown higher sensitivity and better stability towards gas environment. Air pollutants from automobiles and industry waste are the primary sources of environmental pollutants and there is need to develop low temperature, sensitive and selective gas sensors to monitor the gas content. In this paper, we have discussed the effect of Tungsten (W) doping in SnO2 nanostructures on the structural and gas sensing properties. The nanostructures have been synthesized by thermal evaporation process. The structural and surface morphology studies confirm the growth of nanowires on silicon substrates. The corresponding EDX spectra also confirm the doping of W into SnO2 nanowires. The gas sensor response of W-doped SnO2 nanowires was investigated upon exposure to various gases. It has been observed that doping of W enhances the NO2 sensitivity of nanowire based sensors at low temperature and the sensor response improves with increase in gas concentration.

scholarly journals Testing the Reliability of Flexible MOX Gas Sensors under Strain

Proceedings ◽  
2019 ◽  
Vol 14 (1) ◽  
pp. 20
Author(s):  
M. Alvarado ◽  
A. Romero ◽  
J.L. Ramírez ◽  
S. De la Flor ◽  
E. Llobet
Keyword(s):  
Gas Sensors ◽  
Tungsten Trioxide ◽  
Sensor Response ◽  
Bending Test ◽  
Before And After

We present flexible chemo-resistive sensors based on AACVD grown tungsten trioxide (WO3) nanowires. The sensor response to gases, before and after a 50-cycle bending test, is reported. Thus, proving that reliable gas sensors, able to withstand repeated bending, have been achieved. Moreover, their integrity and durability have been tested under harsh bending conditions until break down.

scholarly journals Application of Low-Cost Electrochemical Sensors to Aqueous Systems to Allow Automated Determination of NH3 and H2S in Water

Sensors ◽  
2020 ◽  
Vol 20 (10) ◽  
pp. 2814
Author(s):  
Malcolm Cämmerer ◽  
Thomas Mayer ◽  
Stefanie Penzel ◽  
Mathias Rudolph ◽  
Helko Borsdorf
Keyword(s):  
Mathematical Model ◽  
Gas Sensors ◽  
Water Samples ◽  
Electrochemical Sensors ◽  
Low Cost ◽  
Sensor Response ◽  
Measured Signal ◽  
Gas Streams ◽  
Air Stream ◽  
Low Humidity

Usage of commercially available electrochemical gas sensors is currently limited by both the working range of the sensor with respect to temperature and humidity and the spikes in sensor response caused by sudden changes in temperature or humidity. Using a thermostatically controlled chamber, the sensor response of ammonia and hydrogen sulfide sensors was studied under extreme, rapidly changing levels of humidity with the aim of analyzing nebulized water samples. To protect the sensors from damage, the gas stream was alternated between a saturated gas stream from a Flow Blurring® nebulizer and a dry air stream. When switching between high and low humidity gas streams, the expected current spike was observed and mathematically described. Using this mathematical model, the signal response due to the change in humidity could be subtracted from the measured signal and the sensor response to the target molecule recorded. As the sensor response is determined by the model while the sensor is acclimatizing to the new humid conditions, a result is calculated faster than that by systems that rely on stable humidity. The use of the proposed mathematical model thus widens the scope of electrochemical gas sensors to include saturated gas streams, for example, from nebulized water samples, and gas streams with variable humidity.

Relative Resistance Chemical Sensors Built on Microhotplate Platforms

2007 ◽  
Vol 1052 ◽  
Author(s):  
Joshua L. Hertz ◽  
Christopher B. Montgomery ◽  
David L. Lahr ◽  
Steve Semancik
Keyword(s):  
Gas Sensors ◽  
Chemical Sensors ◽  
Gas Flow ◽  
Gas Flow Rate ◽  
Relative Resistance ◽  
High Reproducibility ◽  
Signal Drift ◽  
Film Forming ◽  
Multiple Sensing ◽  
Over Time

AbstractThe selectivity, sensitivity, and speed of metal oxide conductometric chemical sensors can be improved by integrating them onto micromachined, thermally-controlled platforms (i.e., microhotplates). The improvements largely arise from the richness of signal inherent in arrays of multiple sensing materials and the ability to rapidly pulse and collect data at multiple temperatures. Unfortunately, like their macroscopic counterparts, these sensors can suffer from a lack of repeatability from sample-to-sample and even run-to-run. Here we report on a method to reduce signal drift and increase repeatability that is easily integrated with microhotplate chemical sensors. The method involves passivating one of a pair of identically-formed sensors by coating it with a highly electrically resistive and chemically impermeable film. Relative resistance measurements between the active and passive members of a pair then provide a signal that is reasonably constant over time despite electrical, thermal and gas flow rate fluctuations. Common modes of signal drift, such as microstructural changes within the sensing film, are also removed. The method is demonstrated using SnO2 and TiO2 microhotplate gas sensors, with a thin Al2O3 film forming the passivation layer. It is shown that methanol and acetone at concentrations of 1 µmol/mol, and possibly lower, are sensed with high reproducibility.

scholarly journals Thin Film Gas Sensors Based on Planetary Ball-Milled Zinc Oxide Nanoinks: Effect of Milling Parameters on Sensing Performance

2021 ◽  
Vol 11 (20) ◽  
pp. 9676
Author(s):  
Raju Sapkota ◽  
Pengjun Duan ◽  
Tanay Kumar ◽  
Anusha Venkataraman ◽  
Chris Papadopoulos
Keyword(s):  
Thin Film ◽  
Zinc Oxide ◽  
Gas Sensors ◽  
Zno Nanoparticles ◽  
Food Packaging ◽  
Room Temperature ◽  
Industrial Applications ◽  
Sensor Response ◽  
Particle Sizes ◽  
Zno Nanoparticle

Planetary ball-milled zinc oxide (ZnO) nanoparticle suspensions (nanoinks) were used to produce thin film chemiresistive gas sensors that operate at room temperature. By varying milling or grinding parameters (speed, time, and solvent) different thin film gas sensors with tunable particle sizes and porosity were fabricated and tested with dry air/oxygen against hydrogen, argon, and methane target species, in addition to relative humidity, under ambient light conditions. Grinding speeds of up to 1000 rpm produced particle sizes and RMS thin film roughness below 100 nm, as measured by atomic force and scanning electron microscopy. Raman spectroscopy, photoluminescence, and X-ray analysis confirmed the purity and structure of the resulting ZnO nanoparticles. Gas sensor response at room temperature was found to peak for nanoinks milled at 400 rpm and for 30 min in ethylene glycol and deionized water, which could be correlated to an increased film porosity and enhanced variation in electron concentration resulting from adsorption/desorption of oxygen ions on the surfaces of ZnO nanoparticles. Sensor response and dynamic behavior was found to improve as the temperature was increased, peaking between 100 and 150 °C. This work demonstrates the use of low-cost PBM nanoinks as the active materials for solution-processed thin film gas/humidity sensors for use in environmental, medical, food packaging, laboratory, and industrial applications.

Elaboration of SWNTs-based gas sensors using dispersion techniques: Evaluating the role of the surfactant and its influence on the sensor response

2012 ◽  
Vol 162 (1) ◽  
pp. 95-101 ◽  
Author(s):  
Amadou L. Ndiaye ◽  
Christelle Varenne ◽  
Pierre Bonnet ◽  
Elodie Petit ◽  
Laurent Spinelle ◽  
...  
Keyword(s):  
Gas Sensors ◽  
Sensor Response

scholarly journals Encapsulation Process and Materials Evaluation for E-Textile Gas Sensor

Proceedings ◽  
2019 ◽  
Vol 32 (1) ◽  
pp. 8
Author(s):  
Ashwini Valavan ◽  
Komolafe ◽  
Harris ◽  
Beeby
Keyword(s):  
Carbon Monoxide ◽  
Nitrogen Dioxide ◽  
Gas Sensor ◽  
Gas Sensors ◽  
Sensor Response ◽  
Vehicular Emissions ◽  
Pollution Levels ◽  
Encapsulation Process ◽  
Novel Method ◽  
Exposure Levels

The degree of pollution in the environment increases because of the vehicular emissions such as carbon monoxide (CO) and nitrogen dioxide (NO2) gases. To minimize the exposure levels, it is necessary for individuals to be able to determine for themselves the pollution levels of the environments they are in so that they can take the necessary precautions. Textile-based gas sensors are an emerging solution and this paper furthers the concept by investigating a novel method for encapsulating gas sensors in textiles. While encapsulation is required to improve the durability and lifetime of the sensors, it essential for their operation that the encapsulants do not reduce the sensitivity of the gas sensor. This paper investigates the selectivity of two different flexible and breathable thermoplastic encapsulants (Platilon®U and Zitex G-104) for sensing carbon monoxide by observing the sensor response with and without the encapsulants. Results show that while the encapsulants both enable the sensor to still function, Platilon®U reduces the sensor sensitivity, whereas Zitex G-104 has very little effect.

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