Obtaining Highly Selective Responses from a Bulk Tin Oxide Gas Sensor

2013 ◽  
Vol 543 ◽  
pp. 239-242 ◽  
Author(s):  
Faramarz Hossein-Babaei ◽  
Amir Amini
Keyword(s):  
Gas Sensor ◽  
Gas Sensors ◽  
Tin Oxide ◽  
Low Cost ◽  
High Sensitivity ◽  
Thermal Capacity ◽  
Temperature Modulation ◽  
Custom Made ◽  
Metal Oxide Gas Sensors ◽  
Voltage Spike

Generic gas sensors are commonly used for the detection of different airborne contaminants due to their high sensitivity, long life and low cost, but they generally suffer from the variety of drifts and the lack of selectivity. Different techniques have been developed for selectivity enhancement in metal oxide gas sensors, among which operating temperature modulation is well known. It has been observed that sharp pallet temperature changes provide more analyte-related information. Due to the high thermal capacitance of the device, applying step voltage pulses to a bulk tin oxide gas sensor fails to provide step pallet temperature variations. On the other hand, the low thermal capacity of the custom made microheater gas sensors renders them vulnerable to all kinds of thermal noise and agitations. A novel technique is reported for temperature modulation, which facilitates sharp temperature rises of the gas sensitive pallets in generic gas sensors [. In this technique, a sharp heating voltage spike, considerably surpassing the nominal heating voltage, is applied prior to each heating voltage step. The thermal impact of these spikes is adjusted by controlling v2dt for obtaining the closest variations to the ideal temperature profile. Here, the advantages and effectiveness of the technique are demonstrated by differentiating among iso-butanol, tert-butanol, 1-butanol and 2-butanol contaminations in a wide concentration range in air using only a single generic tin oxide gas sensor.

scholarly journals Semiconductor Metal Oxide Nanoparticles: A Review for the Potential of H2S Gas Sensor Application

2020 ◽  
pp. 199-208
Author(s):  
Zaid Hameed Mahmoud ◽  
Omar Dhaa Abdalstar ◽  
Noor Sabah
Keyword(s):  
Metal Oxide ◽  
Gas Sensor ◽  
Gas Sensors ◽  
Low Cost ◽  
Metal Oxide Nanoparticles ◽  
High Sensitivity ◽  
Modern World ◽  
H2s Gas Sensor ◽  
Work Mechanism ◽  
Semiconductor Metal Oxide

In modern world, gas sensors play important role in many fields of technology used for air pollution, breath analysis, public safety and many others. Gas sensor based semiconductor metal oxide is mostly used in these applications because of low cost, ease-to-use, high sensitivity and lower power consumption. This paper gives an overview about the semiconductor metal oxide and reviews why using it as sensing of gases in electrical applications and then it addresses to the work mechanism of a sensor to sensing H2S gas.

scholarly journals A Sensitive Resonant Gas Sensor Based on Multimode Excitation of a Buckled Beam

2019 ◽  
Author(s):  
Amal Z. Hajjaj ◽  
Nizar Jaber ◽  
Nouha Alcheikh ◽  
Mohammad I. Younis
Keyword(s):  
Thermal Conductivity ◽  
Gas Sensor ◽  
Gas Sensors ◽  
Low Cost ◽  
High Sensitivity ◽  
Gas Absorption ◽  
Surface Areas ◽  
Resistance Variation ◽  
Long Lifetime ◽  
Alternative Approaches

Abstract The quest for ultra-sensitive low-cost miniaturized gas sensors in the past few decades has sparked interest to seek alternative approaches other than the conventional gas sensors that need large surface areas and special chemicals for functionalization. MEMS thermal conductivity based gas sensors [1, 2] have been shown to be among the promising candidates since they do not rely on gas absorption or chemical reactions. These sensors show long lifetime and great stability compared to conventional gas sensor. The thermal conductivity based gas sensors rely on the resistance variation of the heated structures due to gas exposure [1]. Typical values of resistance changes are less than few percent. Here, we present a thermal conductivity based gas sensor relying on frequency shifts of an electrothermally heated bridge operated near the buckling point, which leads to ultra-high sensitivity.

scholarly journals Sensitive and Low-Power Metal Oxide Gas Sensors with a Low-Cost Microelectromechanical Heater

ACS Omega ◽  
2021 ◽  
Author(s):  
Yulong Chen ◽  
Mingjie Li ◽  
Wenjun Yan ◽  
Xin Zhuang ◽  
Kar Wei Ng ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Low Power ◽  
Gas Sensors ◽  
Low Cost ◽  
Metal Oxide Gas Sensors

scholarly journals Acetone Sensing and Catalytic Conversion by Pd-Loaded SnO2

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 5921
Author(s):  
Pascal M. Gschwend ◽  
Florian M. Schenk ◽  
Alexander Gogos ◽  
Sotiris E. Pratsinis
Keyword(s):  
Gas Sensors ◽  
Tin Oxide ◽  
Operating Temperature ◽  
Packed Bed ◽  
Sensor Performance ◽  
Response Recovery ◽  
Recovery Times ◽  
Metal Additives ◽  
Metal Oxide Gas Sensors ◽  
Sensing Performance

Noble metal additives are widely used to improve the performance of metal oxide gas sensors, most prominently with palladium on tin oxide. Here, we photodeposit different quantities of Pd (0–3 mol%) onto nanostructured SnO2 and determine their effect on sensing acetone, a critical tracer of lipolysis by breath analysis. We focus on understanding the effect of operating temperature on acetone sensing performance (sensitivity and response/recovery times) and its relationship to catalytic oxidation of acetone through a packed bed of such Pd-loaded SnO2. The addition of Pd can either boost or deteriorate the sensing performance, depending on its loading and operating temperature. The sensor performance is optimal at Pd loadings of less than 0.2 mol% and operating temperatures of 200–262.5 °C, where acetone conversion is around 50%.

scholarly journals SPM—SEM Investigations of Semiconductor Nanowires for Integrated Metal Oxide Gas Sensors

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 701 ◽  
Author(s):  
Verena Leitgeb ◽  
Katrin Fladischer ◽  
Frank Hitzel ◽  
Florentyna Sosada-Ludwikowska ◽  
Johanna Krainer ◽  
...  
Keyword(s):  
Electron Beam ◽  
Metal Oxide ◽  
Gas Sensor ◽  
Gas Sensors ◽  
Semiconductor Nanowires ◽  
Kelvin Probe ◽  
Sensor Applications ◽  
Sensitivity And Selectivity ◽  
Stable Performance ◽  
Metal Oxide Gas Sensors

Integration of metal oxide nanowires in metal oxide gas sensors enables a new generation of gas sensor devices, with increased sensitivity and selectivity. For reproducible and stable performance of next generation sensors, the electric properties of integrated nanowires have to be well understood, since the detection principle of metal oxide gas sensors is based on the change in electrical conductivity during gas exposure. We study two different types of nanowires that show promising properties for gas sensor applications with a Scanning Probe Microscope—Scanning Electron Microscope combination. Electron Beam Induced Current and Kelvin Probe Force Microscopy measurements with a lateral resolution in the nanometer regime are performed. Our work offers new insights into the dependence of the nanowire work function on its composition and size, and into the local interaction between electron beam and semiconductor nanowires.

Engineering Gas Sensors With Aerosol Nanocrystals

2007 ◽  
Author(s):  
Ganhua Lu ◽  
Liying Zhu ◽  
Stephen Hebert ◽  
Edward Jen ◽  
Leonidas Ocola ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Gas Sensors ◽  
Tin Oxide ◽  
Low Cost ◽  
Hydrogen Gas ◽  
Oxide Surface ◽  
Semiconductor Surface ◽  
Oxide Nanoparticles ◽  
Electrostatic Assembly ◽  
Tin Oxide Nanoparticles

Rutile tin oxide (SnO2) is a wide band gap (3.6 eV at 300K [1]) n-type semiconductor material. It is widely used as sensing elements in gas sensors [2]. The sensing mechanism is generally attributed to the significant change in the electrical resistance of the material associated with the adsorption/desorption of oxygen on the semiconductor surface [3]. The formation of oxygen adsorbates (O2− or O−) results in an electron-depletion surface layer due to the electron transfer from the oxide surface to oxygen [4]. Recent studies [5, 6] have shown that use of tin oxide nanocrystals significantly improves the dynamic response and the sensitivity of sensors since the electron depletion may occur in the whole crystallite. Here we report on the fabrication and characterization of a miniaturized gas sensor based on tin oxide nanocrystals. A simple, convenient and low-cost mini-arc plasma source is used to synthesize high-quality tin oxide nanoparticles in aerosol phase at atmospheric pressure. The nanoparticle sensor is then fabricated by electrostatic assembly of product tin oxide nanoparticles onto e-beam lithographically patterned interdigitated electrodes. The microfabricated nanoparticle sensor exhibits good sensitivity and dynamic response to low-concentration ethanol vapor and hydrogen gas diluted in air.

scholarly journals Embedded Transdermal Alcohol Detection via a Finger Using SnO2 Gas Sensors

Sensors ◽  
2021 ◽  
Vol 21 (20) ◽  
pp. 6852
Author(s):  
Fatima Ezahra Annanouch ◽  
Virginie Martini ◽  
Tomas Fiorido ◽  
Bruno Lawson ◽  
Khalifa Aguir ◽  
...  
Keyword(s):  
Gas Sensors ◽  
Tin Dioxide ◽  
Gas Sensing ◽  
Low Cost ◽  
High Sensitivity ◽  
Rf Magnetron Sputtering ◽  
Alcohol Concentration ◽  
Invasive Technique ◽  
Clear Correlation ◽  
Wide Range

In this paper, we report the fabrication and characterization of a portable transdermal alcohol sensing device via a human finger, using tin dioxide (SnO2) chemoresistive gas sensors. Compared to conventional detectors, this non-invasive technique allowed us the continuous monitoring of alcohol with low cost and simple fabrication process. The sensing layers used in this work were fabricated by using the reactive radio frequency (RF) magnetron sputtering technique. Their structure and morphology were investigated by means of X-ray spectroscopy (XRD) and scanning electron microscopy (SEM), respectively. The results indicated that the annealing time has an important impact on the sensor sensitivity. Before performing the transdermal measurements, the sensors were exposed to a wide range of ethanol concentrations and the results displayed good responses with high sensitivity, stability, and a rapid detection time. Moreover, against high relative humidity (50% and 70%), the sensors remained resistant by showing a slight change in their gas sensing performances. A volunteer (an adult researcher from our volunteer group) drank 50 mL of tequila in order to realize the transdermal alcohol monitoring. Fifteen minutes later, the volunteer’s skin started to evacuate alcohol and the sensor resistance began to decline. Simultaneously, breath alcohol measurements were attained using a DRAGER 6820 certified breathalyzer. The results demonstrated a clear correlation between the alcohol concentration in the blood, breath, and via perspiration, which validated the embedded transdermal alcohol device reported in this work.

scholarly journals Low-Cost and Scalable Platform with Multiplexed Microwell Array Biochip for Rapid Diagnosis of COVID-19

Research ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Yang Wang ◽  
Kaiju Li ◽  
Gaolian Xu ◽  
Chuan Chen ◽  
Guiqin Song ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Reverse Transcriptase ◽  
Low Cost ◽  
High Sensitivity ◽  
High Specificity ◽  
Rapid Diagnosis ◽  
Negative Patient ◽  
Microwell Array ◽  
Custom Made ◽  
User Friendly

Sensitive detection of SARS-CoV-2 is of great importance for inhibiting the current pandemic of COVID-19. Here, we report a simple yet efficient platform integrating a portable and low-cost custom-made detector and a novel microwell array biochip for rapid and accurate detection of SARS-CoV-2. The instrument exhibits expedited amplification speed that enables colorimetric read-out within 25 minutes. A polymeric chip with a laser-engraved microwell array was developed to process the reaction between the primers and the respiratory swab RNA extracts, based on reverse transcriptase loop-mediated isothermal amplification (RT-LAMP). To achieve clinically acceptable performance, we synthesized a group of six primers to identify the conserved regions of the ORF1ab gene of SARS-CoV-2. Clinical trials were conducted with 87 PCR-positive and 43 PCR-negative patient samples. The platform demonstrated both high sensitivity (95.40%) and high specificity (95.35%), showing potentials for rapid and user-friendly diagnosis of COVID-19 among many other infectious pathogens.

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