CO Gas Sensor Research Articles

CO2Gas Sensing Properties of Screen-Printed La2O3/SnO2Thick Film

The present investigation deals with the fabrication of CO2 gas sensor based on La2O3/SnO2 metal-oxide material. In this paper, the sensitive material was prepared by La2O3/SnO2 nanopowder and the addition of 1 wt.% and 3 wt.% platinum (Pt) using high-speed ball milling method. The sensitive film prepared by sensitive powder was printed on alumina (Al2O3) substrate by screen printing method. This film was characterized by X-Ray powder diffraction spectroscopy, and Field-emission scanning electron microscopy. As a result, the prepared 3 wt.% Pt/La2O3/SnO2 thick film sensitive paste exhibits a high sensitivity to increasing the CO2 gas concentration at 225 °C in air atmosphere.

Design of a Gas Sensor Transducer Circuitry With Calibration Ability for CO2 Concentration Detection

In this paper, a gas sensor and the proposed calibration chip are presented. For this paper, a commercially available MG811 CO2 gas sensor is used. The output of the CO2 gas sensor was inputted to the proposed chip, and the output signal of the chip is a pulse stream with its frequency corresponding to gas concentration. All functions of the CO2 gas sensor and the proposed chip have been validated experimentally. After calibration, the concentration range of 426–1359 ppm corresponded to the output frequency range of 285–242 kHz. The measured maximum frequency error was 1.3%.

Characterisation of Nanostructured SnO2 Thin Films Synthesised by Magnetron Sputtering and Application in a Carbon Monoxide Gas Sensor

Tin oxide (SnO2) thin films were deposited onto glass substrates using DC magnetron sputtering system as a CO gas sensor. The dependence of the deposition time on structural, morphological and CO gas sensing properties of SnO2 thin films were investigated. The synthesised SnO2 thin films were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and surface profiler. Also the CO gas sensing properties of SnO2-deposited thin films were performed against a wide range of concentration of CO gas. XRD analysis demonstrated that the degree of crystallinity of the deposited SnO2 thin films strongly depended on the deposition time. Also, SEM and AFM analyses revealed that the size of nanoparticles/agglomerates, and both average and rms surface roughness were enhance with increasing the deposition time. Gas sensors based on these SnO2 nanolayers showed an acceptable response to CO at various concentrations. Also it has been demonstrated that SnO2 sensors are highly suitable for sensing CO gas at comparatively lower operating temperatures.

Pore structure control of activated carbon fiber for CO gas sensor electrode

Pore structure control of activated carbon fiber for CO gas sensor electrode

Comparative Study of Conductivity based Silver Modified ZSM5 & Beta Zeolites as a LPG and CO2 Gas Sensor

Comparative Study of Conductivity based Silver Modified ZSM5 & Beta Zeolites as a LPG and CO2 Gas Sensor

Low concentration CO gas sensing properties of hybrid ZnO architecture

ZnO thin film and nanowire morphologies were employed to fabricate CO gas sensors by using radio frequency magnetron sputtering and chemical vapour deposition growth. The sensing properties were measured at CO gas concentration ranging from 10 to 50ppm at varying operating temperature. The results showed a 5-folded sensitivity and half-reduced response time for the hybrid material based on both thin film and nanowires with respect to thin film only, thus indicating the high potential of morphology tailoring, namely, the surface-to-volume ratio and depletion layer, for the enhancement of ZnO sensing performance.

Sandwiched Long-Period Fiber Grating Fabricated by MEMS Process for CO₂ Gas Detection.

This paper presents an optical fiber gas sensor based on sandwiched long-period fiber grating (SLPFG) that is fabricated via the microelectromechanical systems (MEMS) process and coated with amino silica adsorbent for carbon dioxide (CO2) gas sensing. The amine-modified nanoporous silica foams were coated onto the SLPFG for CO2 adsorption. To characterize the CO2 adsorption of the SLPFG sensor, a gas sensing test was conducted with a mixed gas consisting of 15% CO2 and 85% nitrogen at a flow rate of 0.2 L/min. The results showed that the spectra of the SLPFG were varied with the gas flow within 21 min. After that, the transmission spectra of the SLPFG held steady and exhibited no further change. This phenomenon was caused by the adsorption saturation of the amine-modified nanoporous silica foams which were coated onto the SLPFG. During the absorption process, the transmission was increasing by about 11.27 dB (from −23.11 to −11.84 dB), and the increasing rate of transmission was 0.4598 dB/min. Repeatable adsorption and desorption experiment results showed that the SLPFG CO2 gas sensor exhibited good repeatability and a short response time. The recovery rate for each cycle was about 85%, and the required recovery time was short. Therefore, elaborated SLPFG gas sensor could potentially be used as a gas sensor for monitoring CO2 adsorption in the context of various industrial, agricultural, and household applications.

Silicon microring refractometric sensor for atmospheric CO(2) gas monitoring.

We report a silicon photonic refractometric CO(2) gas sensor operating at room temperature and capable of detecting CO(2) gas at atmospheric concentrations. The sensor uses a novel functional material layer based on a guanidine polymer derivative, which is shown to exhibit reversible refractive index change upon absorption and release of CO(2) gas molecules, and does not require the presence of humidity to operate. By functionalizing a silicon microring resonator with a thin layer of the polymer, we could detect CO(2) gas concentrations in the 0-500ppm range with a sensitivity of 6 × 10(-9) RIU/ppm and a detection limit of 20ppm. The microring transducer provides a potential integrated solution in the development of low-cost and compact CO(2) sensors that can be deployed as part of a sensor network for accurate environmental monitoring of greenhouse gases.

Application of Notched Long-Period Fiber Grating Based Sensor for CO2 Gas Sensing

An inductively coupled plasma etching process to fabricate notched long-period fiber gratings for CO2 gas sensing is proposed in this article. In the gas sensing test, the 15% mixed CO2 gas was used for characterization of CO2 adsorption by the amine-modified nanoporous silica foams of the notched long-period fiber grating sensor. The results shows the spectra were changed with the CO2 gas flow within 13 min. During the absorption process, the transmission of the resonant dip was decreased by 2.884 dB. Therefore, the proposed notched long-period fiber grating gas sensor shows good performance and is suitable as a gas sensor for monitoring the CO2 adsorption process.

The cluster-assembled nanowires based on M12N12 (M = Al and Ga) clusters as potential gas sensors for CO, NO, and NO2 detection.

The advances in cluster-assembled materials where clusters serve as building blocks have opened new opportunities to develop ever more sensitive gas sensors. Here, using density functional theory calculations, the structural and electronic properties of cluster-assembled nanowires based on M12N12 (M = Al and Ga) clusters and their application as gas sensors have been investigated. Our results show that the nanowires can be produced via the coalescence of stable M12N12 fullerene-like clusters. The M12N12-based nanowires have semiconducting electrical properties with direct energy gaps, and are particularly stable at room temperature for long enough to allow for their characterization and applications. Furthermore, we found that the CO, NO, and NO2 molecules are chemisorbed on the M12N12-based nanowires with reasonable adsorption energies and apparent charge transfer. The electronic properties of the M12N12-based nanowires present dramatic changes after the adsorption of the CO, NO, and NO2 molecules, especially their electric conductivity. However, the adsorption of NO2 on the Al12N12-based nanowire is too strong, indicating an impractical recovery time as NO2 sensors. In addition to this, due to reasonable adsorption energies, apparent charge transfer, change in the electric conductivity, and the short recovery time, the Al12N12-based nanowire should be a good CO and NO sensor with quick response as well as short recovery time, while the Ga12N12-based nanowire should be a promising gas sensor for CO, NO, and NO2 detection.

Room Temperature CO Sensing with Metal Oxide Nanoparticles Using work Function Readout

In this work a comparative study of work function readout based CO gas sensing using metal oxide nanoparticles at room temperature is presented. The gas sensing measurements were recorded with the help of Kelvin probe that can measure the change in work function of the sensitive layers when exposed to CO. We detected the enhancement in the CO gas sensing properties of n-type nanocrystalline CeO2 by the introduction of p-type CuO nanoparticles at room temperature. Moreover the inclusion of temperature (T = 100̊C), induced a relatively negative impact in the gas sensing properties of the investigated nanoparticles. The combination of n- and p- type mixed metal oxides has a huge potential to obtain relatively stable gas sensitive layers that can be successfully implied towards low power consuming CO gas sensors.

Highly sensitive and selective CO gas sensor based on a hydrophobic SnO2/CuO bilayer

CO gas sensing mechanism of SnO2/CuO bilayer sensor.

Highly sensitive CO2 sensor based on microrods-like La2O3 thin film electrode

The microrod-like La2O3 thin films are successfully synthesized by chemical bath method for highly sensitive CO2 gas sensor application.

Microwave-assisted hydrolysis preparation of highly crystalline ZnO nanorod array for room temperature photoluminescence-based CO gas sensor

Crystallography plane orientation and surface defect on the nanostructure play an important role in optical gas sensor application due to its peculiar quantum properties. In this paper, we report on a formation of highly oriented (002) plane bounded ZnO nanorods ended with a surface defect hexagonal plane, prepared through microwave assisted hydrolysis within 20s and used as a CO gas detector. A novel photoluminescence-based optical sensor approach was introduced to study the sensor response of the hazardous CO gas as low as 10ppm at room temperature. The effect of ZnO nanorod arrays prepared by microwave-assisted hydrolysis and hydrothermal was studied towards CO gas response. It was found that the ZnO nanorods prepared through a microwave-assisted hydrolysis approach exhibited remarkable response at 81.1% towards 100ppm CO gas exposure and showed an ultrafast recovery time of approximately 2.5min. This provides an excellent sensing approach for operating a low concentration CO gas detection system at room temperature.

Preparation and Characterization of Nanostructured SnO<SUB>2</SUB> Thick Films on Flexible Polyimide Substrates for CO Gas Sensor Application

Preparation and Characterization of Nanostructured SnO<SUB>2</SUB> Thick Films on Flexible Polyimide Substrates for CO Gas Sensor Application

A highly efficient CMOS nanoplasmonic crystal enhanced slow-wave thermal emitter improves infrared gas-sensing devices

The application of plasmonics to thermal emitters is generally assisted by absorptive losses in the metal because Kirchhoff’s law prescribes that only good absorbers make good thermal emitters. Based on a designed plasmonic crystal and exploiting a slow-wave lattice resonance and spontaneous thermal plasmon emission, we engineer a tungsten-based thermal emitter, fabricated in an industrial CMOS process, and demonstrate its markedly improved practical use in a prototype non-dispersive infrared (NDIR) gas-sensing device. We show that the emission intensity of the thermal emitter at the CO2 absorption wavelength is enhanced almost 4-fold compared to a standard non-plasmonic emitter, which enables a proportionate increase in the signal-to-noise ratio of the CO2 gas sensor.

Enhanced CO2 gas-sensing performance of ZnO nanopowder by La loaded during simple hydrothermal method

The use of semiconducting metal oxides to develop highly sensitive CO2 chemi-resistive sensing systems remains an important scientific challenge in the field of gas sensing. In this work, we describe the synthesis, characterization, and application of a very important CO2 gas sensing material ZnO-loaded with different atomic percentages of La prepared by a simple hydrothermal method. Synthesized samples were structurally and thermally characterized. The CO2 sensing characteristics of pure ZnO and La-loaded ZnO were compared using a homemade gas sensing measurement system. The sensitivity, operating temperature, and response/recovery time were systematically investigated based on the change in electrical resistance of the materials in the presence of CO2. Experimental results confirmed that 50at% La-loaded ZnO showed a maximum response to 5000ppm CO2 (65%) at an operating temperature of 400°C. The sensing mechanism of the pure and La-loaded ZnO nanopowders is discussed in detail. We believed that the La-loaded, flower-like ZnO nanopowder offers a potential platform for semiconductor-oxide-based CO2 gas sensors.

The effect of ultraviolet irradiation on the ultra-thin HfO2 based CO gas sensor

In this work, an effort has been made to fabricate ultrathin HfO2/Al2O3 sample by atomic layer deposition method for the fast detection of CO gas at room temperature. The effect of the operating temperature and the UV light on the gas sensing characteristics has been studied. We investigated the optimum operating temperature for the sample by sensing 25 ppm CO and CO2 gases from room temperature to 150 °C for 10 °C steps. The maximum response was obtained at 150 °C for both gases in the measurement temperature range. Also, the photoresponse measurements clearly show the effect of UV light on the sample. At room temperature, sensor showed superior response (14%) for 5 ppm CO gas. The response time of sensor is 6 s to 5 ppm CO gas concentration. The ultrathin HfO2 based sample shows acceptable gas sensitivity for 5 ppm CO gas at room temperature under UV light irradiation.

Effects of Cu addition on CO gas-sensing properties of TiO2 prepared by oxidizing mechanically-synthesized TiN composites

TiN–Cu composites were synthesized in a pressurized N2 atmosphere using a ball milling process. TiO2 sensing materials were added with 0–8at% Cu, which was prepared via oxidation at temperatures of 600 and 800°C. Structural characterization was performed using X-ray diffraction, Field emission scattering electron microscopy (FE-SEM), and Transmission electron microscopy (TEM). Cu addition promoted anatase-to-rutile transformation and grain growth, and the responses of the samples that were oxidized at 600°C with CO gas were enhanced by adding Cu to TiO2 compared with the unmodified TiO2. The TiO2 materials with 4% Cu showed the greatest response to CO of 4.1 at 1000ppm of CO gas, which can be compared to the response value of 1.2 of unmodified TiO2–CO gas under identical conditions. The enhancement of TiO2 sensitivity to CO gas is believed to originate from well-dispersed metallic and Cu oxides, which are known catalysts for the oxidation of CO gas. When the oxidation temperature was increased to 800°C, the strongly bound CuO particles dissociated, and the response changed to p-type. It is proposed that the segregation induces a conduction pathway through CuO.

Microwave assisted synthesis of hierarchical Pd/SnO2 nanostructures for CO gas sensor

In this paper, we present a facile one-step microwave assisted hydrothermal route for the synthesis of the unloaded and Pd-loaded SnO2 nanostructures. The Pd was grown in situ on the SnO2 nanostructure, constructing Pd/SnO2. A gas sensor based on the as-prepared Pd/SnO2 was fabricated and tested for response to carbon monoxide gas. The results indicated that the sensor using 3.0wt% Pd-loaded SnO2 to 100ppm carbon monoxide performed a superior sensing properties compared to 0wt%, 1.5wt%, and 4.5wt% Pd-loaded samples at a relatively low temperature (100°C). Such enhanced gas sensing performances could be attributed to both the contribution of Pd-loaded and the in situ method. In addition, the one-step in situ microwave assisted loading process provides a promising and versatile choice for the preparation of gas sensing materials.