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Sembodo, Shafanda Nabil, Nazrul Effendy, Kenny Dwiantoro, and Nidlom Muddin. "Radial basis network estimator of oxygen content in the flue gas of debutanizer reboiler." International Journal of Electrical and Computer Engineering (IJECE) 12, no. 3 (2022): 3044. http://dx.doi.org/10.11591/ijece.v12i3.pp3044-3050.
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<span>The energy efficiency in the debutanizer reboiler combustion can be monitored from the oxygen content of the flue gas of the reboiler. The measurement of the oxygen content can be conducted in situ using an oxygen sensor. However, soot that may appear around the sensor due to the combustion process in the debutanizer reboiler can obstruct the sensor’s function. In-situ redundancy sensors’ unavailability is a significant problem when the sensor is damaged, so measures must be made directly by workers using portable devices. On the other hand, worker safety is a primary concern when working in high-risk work areas. In this paper, we propose a software-based measurement or soft sensor to overcome the problems. The radial basis function network model makes soft sensors adapt to data updates because of their advantage as a universal approximator. The estimation of oxygen content with a soft sensor has been successfully carried out. The soft sensor generates an estimated mean square error of 0.216% with a standard deviation of 0.0242%. Stochastics gradient descent algorithm with momentum acceleration and dimension reduction using principal component analysis successfully improves the soft sensors’ performance.</span>
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Zhang, Mao Lin, Tao Ning, and Yu Hong Yang. "Gas Response Properties of Noble Metal Modified TiO2 Gas Sensor." Advanced Materials Research 706-708 (June 2013): 126–29. http://dx.doi.org/10.4028/www.scientific.net/amr.706-708.126.
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The response characteristics of noble metal (platinum and palladium) modified TiO2 gas sensors were investigated, respectively. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to characterize the sensing films. In addition, the resistance of sensors response to oxygen partial pressure was discussed by Kroger–Vink model. The response properties indicated that Pt modified TiO2 was providing excellent response properties when the sensor exposed to hydrogen and oxygen. The response mechanism was suggested to arise from the activation energy (E) of the modified sensing films.
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Duan, Chao, Lejun Zhang, Zhaoxi Wu, Xu Wang, Meng Meng, and Maolin Zhang. "Study on the Deterioration Mechanism of Pb on TiO2 Oxygen Sensor." Micromachines 14, no. 1 (2023): 156. http://dx.doi.org/10.3390/mi14010156.
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Previous studies have shown that the pollutants in exhaust gas can cause performance deterioration in air-fuel oxygen sensors. Although the content of Pb in fuel oil is as low as 5 mg/L, the effect of long-term Pb accumulation on TiO2 oxygen sensors is still unclear. In this paper, the influence mechanism of Pb-containing additives in automobile exhaust gas on the response characteristics of TiO2 oxygen sensors was simulated and studied by depositing Pb-containing pollutants on the surface of a TiO2 sensitive film. It was found that the accumulation of Pb changed the surface gas adsorption state and reduced the activation energy of TiO2, thus affecting the steady-state response voltage and response speed of the TiO2-based oxygen sensor.
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Sun, Jingxia, Aimin Zhang, Guoqiang Gong, and Jian Jiang. "Study on calibration period of Gas Sensor in exercise Pulmonary Function instrument." Modern Electronic Technology 2, no. 3 (2018): 66. http://dx.doi.org/10.26549/met.v2i3.1133.
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Objective: to study the calibration period of the main motor pulmonary function instrument sensor. Methods: A matched control group was used, one was calibrated periodically and the other was not calibrated. The calibration values of oxygen sensor and carbondioxide sensor were compared. Results: the oxygen sensor of electrochemical type was most sensitive to the change of time and environment, and the carbon dioxide sensor of infrared type was more sensitive to the change of time and environment. Conclusion: oxygen sensors of electrochemical type and carbon dioxide sensors of infrared type should be calibrated before each use.
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Liu, Jianqiao, Wanqiu Wang, Zhaoxia Zhai, et al. "Influence of Oxygen Vacancy Behaviors in Cooling Process on Semiconductor Gas Sensors: A Numerical Analysis." Sensors 18, no. 11 (2018): 3929. http://dx.doi.org/10.3390/s18113929.
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The influence of oxygen vacancy behaviors during a cooling process in semiconductor gas sensors is discussed by the numerical analysis method based on the gradient-distributed oxygen vacancy model. A diffusion equation is established to describe the behaviors of oxygen vacancies, which follows the effects of diffusion and exclusion in the cooling process. Numerical analysis is introduced to find the accurate solutions of the diffusion equation. The solutions illustrate the oxygen vacancy distribution profiles, which are dependent on the cooling rate as well as the temperature interval of the cooling process. The gas-sensing characteristics of reduced resistance and response are calculated. Both of them, together with oxygen vacancy distribution, show the grain size effects and the re-annealing effect. It is found that the properties of gas sensors can be controlled or adjusted by the designed cooling process. The proposed model provides a possibility for sensor characteristics simulations, which may be beneficial for the design of gas sensors. A quantitative interpretation on the gas-sensing mechanism of semiconductors has been contributed.
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Russ, Tamara, Joseph R. Stetter, David Peaslee, Vinay Patel, Firouzeh Mohadjerani, and Edward F. Stetter. "RTILs as Electrolytes in Electrochemical Gas Sensors for O2 and Other Gases." ECS Meeting Abstracts MA2023-01, no. 52 (2023): 2603. http://dx.doi.org/10.1149/ma2023-01522603mtgabs.
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Oxygen is the third-most abundant element on this planet and is essential to life, the lifestyle of humans and virtually all sentient life. We need O2 to live and additionally use it for both heating and transportation. Since O2 is so essential in our everyday life, there are several applications where the oxygen levels need to be controlled or maintained within a certain range. To make sure that the O2 level is within the necessary range, devices are needed that can monitor and feedback/communicate O2 levels continuously. There are several types of chemical gas sensors for O2 which include chemoresistive gas sensors and electrochemical gas sensors. The Clark-type electrochemical sensor is the oldest and probably the most used sensor for oxygen especially in medical applications. One of the most well-known industrial applications for gas-phase oxygen sensors is probably the control of oxygen levels in combustion engines with the help of a Lambda probe, a solid-state electrochemical cell operated in amperometric and potentiometric modes. Electrochemical sensors have evolved over the past decades. By finding the suitable combination of electrolyte, electrode material, cell design and operation conditions, electrochemical sensors are tunable to meet the specific requirements of the many different applications. For example, by changing the electrode material from gold to platinum while keeping everything else the same, you can reduce the response to CO by orders of magnitude improving the selectivity in low level measurements. Further, by adjusting the thermodynamic voltage of the sensing electrode, the electrochemical reactivity is adjusted to maximize the sensor’s selectivity for the target analyte. While these developments have occurred over time, recent work implements room temperature ionic liquids (RTILs) as electrolytes. This idea has some serious merit to it for multiple reasons. Firstly, many electrochemical sensors have aqueous electrolytes which freeze at low temperatures and rapidly evaporate at elevated temperatures. Additionally, aqueous electrolytes can change in real time with variations in background humidity levels. To be more exact, aqueous electrolytes dry out when operated in low humidity backgrounds and significantly increase in volume (swell) in high humidity background levels. While drying out is an issue because this leads to poor ionic conductivities, swelling is an issue because the electrolyte needs expansion room in the sensor, typically an extensive cavity within the cell body. RTILs have shown promise because they can extend the operating temperature range as well as lead to new sensor designs operatable over a wider range of environmental conditions. The implementation of RTILs might even allow for smaller sensor designs due to a smaller volume change of the electrolyte in dependence of changing humidity levels. Several research groups have investigated the oxygen sensing capabilities of RTILs in electrochemical devices. Silvester et al. investigated the oxygen solubility in several different imidazolium cations combined with [bis(trifluoromethylsulfonyl)imide] ([NTf2]-) anions and found a high oxygen solubility in 3-butyl-1-methyl imidazolium [NTf2]- [1]. They further investigated the influence of humidity on the oxygen reduction reaction and found the most stable behavior for [3-etyhl-1-methyl imidiazolium] [NTf2]- over a broad range of different humidity levels [2]. Yin et al. investigated 1-butyl-1-methylpyrrolidinium [NTf2]- as an electrolyte in oxygen sensors and found good linear correlation of the sensor output to the oxygen concentration [3]. In this work, we investigated different RTILs, including the before mentioned 1-butyl-1-methylpyrrolidinium [NTf2]- and 3-butyl-1-methyl imidazolium [NTf2]-, regarding their suitability for thin layer electrochemical oxygen sensors in a background of mostly nitrogen. The performance was investigated using CV (cyclic voltammetry) and other time dependent voltametric techniques. The ability to detect oxygen of sensors with different RTILs as electrolyte was compared to that of aqueous H2SO4. [1] S. Doblinger, D.S. Silvester, M. Costa Gomes, Functionalized Imidazolium Bis(trifluoromethylsulfonyl)-imide Ionic Liquids for Gas Sensors: Solubility of H2, O2 and SO2, Fluid Phase Equilib. 549 (2021). https://doi.org/10.1016/j.fluid.2021.113211. [2] S. Doblinger, J. Lee, D.S. Silvester, Effect of Ionic Liquid Structure on the Oxygen Reduction Reaction under Humidified Conditions, Journal of Physical Chemistry C. 123 (2019) 10727–10737. https://doi.org/10.1021/acs.jpcc.8b12123. [3] H. Yin, H. Wan, L. Lin, X. Zeng, A.J. Mason, Miniaturized Planar RTIL-based Electrochemical Gas Sensor for Real-Time Point-of-Exposure Monitoring, 2016 IEEE Healthcare Innovation Point-Of-Care Technologies Conference (HI-POCT). (2016) 85–88. https://doi.org/10.1109/HIC.2016.7797703.
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Agustinur, Satya Cantika, Khaled Issa Khalifa, Meta Yantidewi, and Utama Alan Deta. "Literature Review: Air Oxygen Level Monitoring System." International Journal of Research and Community Empowerment 1, no. 2 (2023): 62–70. http://dx.doi.org/10.58706/ijorce.v1n2.p62-70.
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Oxygen is a very important gas for humans. The need for oxygen around the plant is very low because the exhaust gas from various factories often becomes pollutants, one of which is the cement industry. The oxygen content needs to be known so that the level of vigilance of workers and the community is higher. For this reason, it is necessary to make a monitoring device for oxygen content. In this view will be discussed several gas sensors, especially oxygen sensors. In addition, Arduino microcontrollers and Raspberry Pi microprocessors were also discussed. The goal is to be able to determine the type of oxygen sensor as a detector of oxygen levels in the air. The discussion of microcontrollers and microprocessors is also a determinant of the motherboard connected to the oxygen sensor. Thus, the explanation of this review can be used to develop a monitoring system for oxygen content in the air. The research method used is in the form of literature studies. Literature study is the process of finding research data or information by reading scientific journals, reference books, and articles about oxygen content monitoring devices. This tool functions as a gas analyzer by choosing the MQ-135 sensor as an oxygen sensor because it is more affordable and easy to obtain which is supported by the Raspberry Pi device.
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Vasiliev, Alexey, Alexey Shaposhnik, Oleg Kul, and Artem Mokrushin. "The Role of Convection and Size Effects in Microhotplate Heat Exchange: Semiconductor and Thermomagnetic Gas Sensors." Sensors 25, no. 9 (2025): 2830. https://doi.org/10.3390/s25092830.
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The analysis of the influence of microhotplate size on the convective heat exchange of gas sensors is presented. Usually, the role of convection in the heat exchange of gas sensors is not considered in thermal simulation models because of the complexity of the convection process. As a result, the contribution of this process to the overall heat loss of sensors remains without detailed analysis. We analyzed convection issues in two groups of gas sensors: semiconductor and thermocatalytic (calorimetric) sensors and, on the other hand, in the oxygen sensors of the thermomagnetic type. It is demonstrated that there is a critical size leading to the formation of convective heat exchange flow. Below this critical value, only thermal conductivity of ambient air, IR (infrared) radiation from the heated microhotplate surface, and thermal conductivity of the microhotplate-supporting elements should be considered as channels for heat dissipation by the microhotplate, and the contribution of free convection can be neglected. The expression for the critical size contains only fundamental constants of air, dcr~4·ν·Dg3, where ν is the kinematic viscosity of air, D is the diffusion coefficient, and g is the acceleration of free fall, dcr~0.5 cm. Therefore, if the size of the microhotplate d <<dcr, the influence of convection heat exchange can be neglected. Similar results were obtained in the analysis of the behavior of thermal magnetic sensors of oxygen, which use paramagnetic properties of molecular oxygen for the determination of O2 concentration. In this case, the critical size of the sensor is also of significance; if the size of the magnetic sensor is much below this value, the oxygen concentration value measured with such a device is independent of the orientation of the sensor element. The results of the simulation were compared with the measurement of heat loss in micromachined gas sensors. The optimal dimensions of the sensor microhotplate are given as a result of these simulations and measurements.
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Shafanda, Nabil Sembodo, Effendy Nazrul, Dwiantoro Kenny, and Muddin Nidlom. "Radial basis network estimator of oxygen content in the flue gas of debutanizer reboiler." International Journal of Electrical and Computer Engineering (IJECE) 12, no. 3 (2022): 3044–50. https://doi.org/10.11591/ijece.v12i3.pp3044-3050.
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The energy efficiency in the debutanizer reboiler combustion can be monitored from the oxygen content of the flue gas of the reboiler. The measurement of the oxygen content can be conducted in situ using an oxygen sensor. However, soot that may appear around the sensor due to the combustion process in the debutanizer reboiler can obstruct the sensor’s function. In-situ redundancy sensors’ unavailability is a significant problem when the sensor is damaged, so measures must be made directly by workers using portable devices. On the other hand, worker safety is a primary concern when working in high-risk work areas. In this paper, we propose a software-based measurement or soft sensor to overcome the problems. The radial basis function network model makes soft sensors adapt to data updates because of their advantage as a universal approximator. The estimation of oxygen content with a soft sensor has been successfully carried out. The soft sensor generates an estimated mean square error of 0.216% with a standard deviation of 0.0242%. Stochastics gradient descent algorithm with momentum acceleration and dimension reduction using principal component analysis successfully improves the soft sensors’ performance.
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Maskell, W. C., and B. C. H. Steele. "Solid state potentiometric oxygen gas sensors." Journal of Applied Electrochemistry 16, no. 4 (1986): 475–89. http://dx.doi.org/10.1007/bf01006843.
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Tutunea, Dragos, Ilie Dumitru, Oana Victoria Oţăt, Laurentiu Racila, Ionuţ Daniel Geonea, and Claudia Cristina Rotea. "Oxygen Sensor Testing for Automotive Applications." Applied Mechanics and Materials 896 (February 2020): 249–54. http://dx.doi.org/10.4028/www.scientific.net/amm.896.249.
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During the operation of internal combustion engines the air-fuel ratio (A/F) is an important parameter which affects fuel consumption and pollutant emissions. The automotive oxygen sensor (Lambda) measures the quantity of residual oxygen in the combustion gases. Sensor degradation in time due to the exposure to high temperatures causes a distortion in controlling the A/F with the increase in gas emissions. In this paper an experimental stand is designed to test oxygen sensor degradation in laboratory condition. Four oxygen sensors were tested function of temperature and time recording their variation in resistance and voltage. The results showed similar values in the curves for all sensors tested.
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Shu, Lin, Xuemin Wang, Dawei Yan, Long Fan, and Weidong Wu. "The Investigation of High-Temperature SAW Oxygen Sensor Based on ZnO Films." Materials 12, no. 8 (2019): 1235. http://dx.doi.org/10.3390/ma12081235.
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In this paper, a wireless oxygen sensor based on a surface acoustic wave (SAW) was reported. For high-temperature applications, novel Al2O3/ZnO/Pt multilayered conductive film was deposited on langasite substrate as the electrodes, and ZnO film obtained by the pulse laser deposition (PLD) method was used as the sensitive film. The measurements of X-ray diffraction (XRD) and a scanning electron microscope (SEM) showed that the c-axis orientation of the ZnO grains and the surface morphology of the films were regulated by the deposition temperature. Meanwhile, the gas response of the sensor was strongly dependent on the surface morphology of the ZnO film. The experimental results showed that the oxygen gas sensor could operate at a high-temperature environment up to 850 °C with good stability for a long period. The max frequency shift of the sensors reaches 310 kHz, when exposed to 40% O2 gas at 850 °C. The calculated standard error of the sensors in a high-temperature measurement process is within 3%. Additionally, no significant signal degradation could be observed in the long-term experimental period. The prepared SAW oxygen gas sensor has potential applications in high-temperature sensing systems.
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Hendryani, Atika, Vita Nurdinawati, and Nashrul Dharma. "Design of Manifold with Pressure Controller for Automatic Exchange of Oxygen Gas Cylinders in Hospital." TEKNIK 42, no. 1 (2021): 45–51. http://dx.doi.org/10.14710/teknik.v42i1.33127.
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The regulation and supply of oxygen as one of the medical gases in the hospital is important to ensure the availability of these gases for the survival of patients. The regulation of oxygen gas in hospitals usually uses a piping system with manifolds. The manifold will monitor the oxygen gas pressure on each tube. Manifold systems that are widely used in general can only monitor pressure but cannot perform an automatic exchange on gas cylinders if the pressure is under the permissible conditions. The manifold system design developed is equipped with pressure monitoring for automatic exchange of oxygen gas cylinders using pressure sensors and microprocessors. The test results of the system using regulator and barometer comparisons showed the percentage value of sensor pressure accuracy of 96.92 percent and 97.16 percent. At pressure below the limit of 285 KPa manifold can perform the exchange of active gas cylinders automatically. These results show the manifold design built can work quite well.
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Torkamani Cheriani, Mahmoud, and Ali Mirzaei. "Plasma-Treated Nanostructured Resistive Gas Sensors: A Review." Sensors 25, no. 7 (2025): 2307. https://doi.org/10.3390/s25072307.
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Resistive gas sensors are among the most widely used sensors for the detection of various gases. In this type of gas sensor, the gas sensing capability is linked to the surface properties of the sensing layer, and accordingly, modification of the sensing surface is of importance to improve the sensing output. Plasma treatment is a promising way to modify the surface properties of gas sensors, mainly by changing the amounts of oxygen ions, which have a central role in gas sensing reactions. In this review paper, we focus on the role of plasma treatment in the gas sensing features of resistive gas sensors. After an introduction to air pollution, toxic gases, and resistive gas sensors, the main concepts regarding plasma are presented. Then, the impact of plasma treatment on the sensing characteristics of various sensing materials is discussed. As the gas sensing field is an interdisciplinary field, we believe that the present review paper will be of significant interest to researchers with various backgrounds who are working on gas sensors.
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Sricharoen, C., T. Waritananta, N. Wattanavicheana, R. Jaisuthi, and T. Osotchan. "Flow dependence of handheld breath analyzer for body fuel utilization monitoring." Journal of Physics: Conference Series 2431, no. 1 (2023): 012017. http://dx.doi.org/10.1088/1742-6596/2431/1/012017.
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Abstract Home healthcare medical technologies have been gaining popularity and are more affordable in recent years. Exhaled breath analysis has potential in this field. The development of gas sensor technology has enabled us to build a small affable breath analysis device with the electronic nose concept. In this work, a handheld breath analyzer was developed for monitoring body fuel utilization. A hybrid gas sensor array, including electrochemical and photoacoustic gas sensors, was used to accurately measure oxygen and carbon dioxide in exhaled breath. The bypass configuration volume flow measurement method was developed to fit a small portable device. The experiment shows that both oxygen and carbon dioxide sensors are flow-dependent due to the slow response time of each sensor type. The response of the photoacoustic sensor is relatively slower than those of other sensor types. Thus, a mathematical model was developed to correct the individual sensor value to get a more accurate value of body fuel utilization. The comparison protocol of known concentrations of the oxygen and carbon gases with various flow conditions was conducted, and the mathematical model for reconstructing the original gas concentration was proposed. The result shows that the device is able to detect the RER change of humans after having a high carbohydrate content meal and after exercise
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Stetter, Joseph R., and Tamara Russ. "(Invited) Past, Present and Future for Electrochemical Gas Sensors in Energy Applications." ECS Meeting Abstracts MA2024-01, no. 51 (2024): 2750. http://dx.doi.org/10.1149/ma2024-01512750mtgabs.
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The markets for modern low-cost electrochemical gas sensors have been growing for longer than sensors have been around. Energy markets for gas sensors include the oil, gas and electricity industries as well as the new developing and fast growing green energy sectors. The primary gases to detect include combustible hydrocarbons, oxygen, and toxic gases. Specifically, we are interested in methane (blue and green), ammonia, and H2 for the renewable energy sectors but include hydrocarbon fuels and CO2 as a greenhouse gas emission. The reasons for monitoring crosscut all areas of the energy business and include applications in production, transport, storage and use. Primary sensor uses include: 1) health and safety (people and assets), 2) leak detection and isolation to help mitigate product losses, 3) monitoring to protect the environment and 4) measurements for process control and efficacy. Each of these areas of sensing have special requirements and demand cost-effective and time efficient sensor performance in many and varied real world scenarios. Electrochemical gas sensors have a long and rich history starting with the commercialization of the first practical potentiometric CO2 gas sensor by Severinghaus in 1954 and the O2 amperometric sensor by Clark in 1956 that launched the modern blood gas analysis industry. Additional milestones include the introduction of the “diffusion electrode” in 1968 creating the modern amperometric sensor which has produced a large array of sensors for toxic and hazardous gases including H2, ammonia, and other energy gases. Progress has been made in the field of electrochemical gas sensors, not only in improving performance, sensitivity, selectivity, response time, and stability, but also in logistical properties including miniaturization, lower power consumption, low cost as well as communication and computation to make automated-operational systems. New high-volume production has contributed to lower costs commensurate with a chip-based sensor mentality. The evolution of one of the gas sensor technologies is given below (the room temperature AGS or amperometric gas sensor) and similar progress has been seen in mixed potential and solid state gas sensors. The growing understanding of the sensor’s fundamental electrocatalytic reactions has led to tailored designs of electrode-electrolyte combinations and packages for the various applications. Often ignored in sensor publications of performance, the fundamental electrocatalytic studies are poised to make significant advances in energy gas sensor selectivity and sensitivity. The additional implementation of intelligent algorithms (AI/ML) to make “smart” sensors and sensor arrays complements advanced nano-materials and designs for improving sensor performance. One major improvement is our understanding of the sensor response mechanisms at the electrocatalytic level. This new research will enable new electrochemical sensor advances that are poised to impact the health and wellbeing of both people and the planet. Ideas and concepts that significantly contribute to the safe and efficient rollout of the newest green energy platforms are presented. Figure 1
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Nalimova, Svetlana, Zamir Shomakhov, Anton Bobkov, and Vyaсheslav Moshnikov. "Sacrificial Doping as an Approach to Controlling the Energy Properties of Adsorption Sites in Gas-Sensitive ZnO Nanowires." Micro 3, no. 2 (2023): 591–601. http://dx.doi.org/10.3390/micro3020040.
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Currently, devices for environmental gas analyses are required in many areas of application. Among such devices, semiconductor-resistive gas sensors differ advantageously. However, their characteristics need further improvement. The development of methods for controlling the surface properties of nanostructured metal oxides for their use as gas sensors is of great interest. In this paper, a method involving the sacrificial doping of ZnO nanowires to control the content of their surface defects (oxygen vacancies) was proposed. Zinc oxide nanowires were synthesized using the hydrothermal method with sodium iodide or bromide as an additional precursor. The surface composition was studied using X-ray photoelectron spectroscopy. The sensor properties of the isopropyl alcohol vapors at 150 °C were studied. It was shown that a higher concentration of oxygen vacancies/hydroxyl groups was observed on the surfaces of the samples synthesized with the addition of iodine and bromine precursors compared to the pure zinc oxide nanowires. It was also found out that these samples were more sensitive to isopropyl alcohol vapors. A model was proposed to explain the appearance of additional oxygen vacancies in the subsurface layer of the zinc oxide nanowires when sodium iodide or sodium bromide was added to the initial solution. The roles of oxygen vacancies and surface hydroxyl groups in providing the samples with an increased sensitivity were explained. Thus, a method involving the sacrificial doping of zinc oxide nanowires has been developed, which led to an improvement in their gas sensor characteristics due to an increase in the concentration of oxygen vacancies on their surface. The results are promising for percolation gas sensors equipped with additional water vapor traps that work stably in a high humidity.
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Sharif, Niloufar, and Ardemis Anoush Boghossian. "Carbon Nanotube-Based Sensors for Intelligent Packaging." ECS Meeting Abstracts MA2023-01, no. 10 (2023): 1225. http://dx.doi.org/10.1149/ma2023-01101225mtgabs.
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Aim: The aim of this project is to develop a gas-phase optical sensor for oxygen detection in intelligent packaging. The optical sensor will be based on near-infrared light that can penetrate through visibly opaque materials, including plastics, paper, and cardboard. An automated near-infrared camera will be used to precisely and quickly inform the user of any change in the integrity of packages that are vacuum-sealed or atmospherically modified. Method: The optical sensor is based on near-infrared fluorescence that is emitted from carbon nanotubes (CNTs). CNTs exhibit a sensitive and photostable fluorescence that is well suited for sensing applications. The CNTs are wrapped by one of two types of DNA, AT(15) and GT(15), through sonication. These wrappings control the responsivity of the CNTs to different gases while also solubilizing them for further processing. The resulting solutions are then drop-casted into a film. We subsequently investigate the response of the film in the presence of the target gas, oxygen, at different concentrations. Finally, we evaluate the selectivity of the sensor in the presence other gases including carbon dioxide, ethylene, and ammonia. Results: Our results reveal that the fluorescence intensity of the AT(15) and GT(15)-wrapped CNTs quenches upon the exposure of oxygen. Interestingly, we observe that the different CNT chiralities respond distinctly to the presence of oxygen. In particular, whereas some chiralities undergo an irreversible loss in fluorescence after several oxygen exposure cycles, the (8,6) chirality demonstrates stability over multiple cycles for both AT(15) and GT(15)-wrapped CNTs. Finally, our results show a concentration-dependent and selective response of both the AT(15)- or GT(15)-wrapped CNT sensors to the oxygen, as we observed no significant response to the other studied gases. Conclusion: We developed an optical, gas-phase sensor based on CNT fluorescence for intelligent food packaging. The sensor is selective to oxygen and demonstrates reversibility over multiple oxygen exposure cycles. These sensors can be used to monitor the integrity of packages that are vacuum-sealed or otherwise atmospherically modified. This technology can thus provide consumers and manufactures a means of preventing early spoilage and ensuring food quality.
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Paz Alpuche, Emilio, Pascal Gröger, Xuetao Wang, Thomas Kroyer, and Stefanos Fasoulas. "Influence of the Sputtering Technique and Thermal Annealing on YSZ Thin Films for Oxygen Sensing Applications." Coatings 11, no. 10 (2021): 1165. http://dx.doi.org/10.3390/coatings11101165.
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Yttria-stabilized zirconia (YSZ) thin films were deposited using direct current (reactive and metallic) and radio frequency magnetron sputtering. The effect of the deposition technique and annealing treatment on the microstructure and crystallinity of the thin films was assessed. Using the films produced in this work, oxygen gas sensors were built and their performance under vacuum conditions was evaluated. All the films exhibited a cubic crystalline structure after a post-deposition thermal treatment, regardless of the sputtering technique. When the annealing treatment surpassed 1000 °C, impurities were detected on the thin film surface. The oxygen gas sensors employing the reactive and oxide-sputtered YSZ thin films displayed a proportional increase in the sensor current as the oxygen partial pressure was increased in the evaluated pressure range (5 × 10−6 to 2 × 10−3 mbar). The sensors which employed the metallic-deposited YSZ films suffered from electronic conductivity at low partial pressures.
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Liang, Meihua, Yong Yan, Jiaxuan Yang, et al. "In Situ-Derived N-Doped ZnO from ZIF-8 for Enhanced Ethanol Sensing in ZnO/MEMS Devices." Molecules 29, no. 8 (2024): 1703. http://dx.doi.org/10.3390/molecules29081703.
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Microelectromechanical systems (MEMS) gas sensors have numerous advantages such as compact size, low power consumption, ease of integration, etc., while encountering challenges in sensitivity and high resistance because of their low sintering temperature. This work utilizes the in situ growth of Zeolitic Imidazolate Framework-8 (ZIF-8) followed by its conversion to N-doped ZnO. The results obtained from scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicate that the in situ derivation of ZIF-8 facilitates the adhesion of ZnO particles, forming an island-like structure and significantly reducing the interfaces between these particles. Furthermore, powder X-ray diffraction (XRD) analysis, elemental mapping, and X-ray photoelectron spectroscopy (XPS) analysis confirm the conversion of ZIF-8 to ZnO, the successful incorporation of N atoms into the ZnO lattice, and the creation of more oxygen vacancies. The ZIF-8-derived N-doped ZnO/MEMS sensor (ZIF (3)-ZnO/MEMS) exhibits remarkable gas sensitivity for ethanol detection. At an operating temperature of 290 °C, it delivers a substantial response value of 80 towards 25 ppm ethanol, a 13-fold enhancement compared with pristine ZnO/MEMS sensors. The sensor also exhibits an ultra-low theoretical detection limit of 11.5 ppb to ethanol, showcasing its excellent selectivity. The enhanced performance is attributed to the incorporation of N-doped ZnO, which generates abundant oxygen vacancies on the sensor’s surface, leading to enhanced interaction with ethanol molecules. Additionally, a substantial two-order-of-magnitude decrease in the resistance of the gas-sensitive film is observed. Overall, this study provides valuable insights into the design and fabrication strategies applicable to high-performance MEMS gas sensors in a broader range of gas sensing.
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Pan, Hongyin, Chenyu Wang, Zexu Zhang, et al. "Oxygen vacancy-enriched ALD NiO sub-50 nm thin films for enhanced triethylamine detection." Applied Physics Letters 121, no. 11 (2022): 111603. http://dx.doi.org/10.1063/5.0104480.
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p-type metal oxide semiconductors have received significant interest in the field of gas sensors; however, it is quite challenging to achieve high sensor response because of inferior surface and electronic properties. Herein, we report a high-performance gas sensor fabricated by plasma-etching an NiO thin film deposited by atomic layer deposition. Ar plasma treatment is found to introduce a large number of oxygen vacancies, which effectively adjusts the electronic and chemical characteristics of the p-type NiO films to afford improved response to toxic triethylamine. The effects of the thickness of the sensing layer on sensor properties are also studied, which reveals that the NiO film with a thickness of 40 nm has the greatest gas sensing performance. After Ar plasma treatment, the response of the NiO thin films is significantly enhanced to enable an excellent limit of detection of 27.4 ppb, which is much lower than the threshold limit of 1 ppm proposed by American Conference of Governmental Industrial Hygienists. The demonstrated strategy and excellent sensor properties suggest a pathway to high performance gas sensors.
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Huang, Qingwu, Jinjin Wu, Dawen Zeng, and Peng Zhou. "Graphene-Wrapped ZnO Nanocomposite with Enhanced Room-Temperature Photo-Activated Toluene Sensing Properties." Materials 17, no. 5 (2024): 1009. http://dx.doi.org/10.3390/ma17051009.
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Graphene-wrapped ZnO nanocomposites were fabricated by a simple solvothermal technology with a one-pot route. The structure and morphology of these as-fabricated samples were systematically characterized. The adding of graphene enhanced the content of the oxygen vacancy defect of the sample. All gas-sensing performances of sensors based on as-prepared samples were thoroughly studied. Sensors displayed an ultrahigh response and exceptional selectivity at room temperature under blue light irradiation. This excellent and enhanced toluene gas-sensing property was principally attributed to the synergistic impacts of the oxygen vacancy defect and the wrapped graphene in the composite sensor. The photo-activated graphene-wrapped ZnO sensor illustrated potential application in the practical detection of low concentrations of toluene under explosive environments.
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Müller, Gerhard, and Giorgio Sberveglieri. "Origin of Baseline Drift in Metal Oxide Gas Sensors: Effects of Bulk Equilibration." Chemosensors 10, no. 5 (2022): 171. http://dx.doi.org/10.3390/chemosensors10050171.
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Metal oxide (MOX) gas sensors and gas sensor arrays are widely used to detect toxic, combustible, and corrosive gases and gas mixtures inside ambient air. Important but poorly researched effects counteracting reliable detection are the phenomena of sensor baseline drift and changes in gas response upon long-term operation of MOX gas sensors. In this paper, it is shown that baseline drift is not limited to materials with poor crystallinity, but that this phenomenon principally also occurs in materials with almost perfect crystalline order. Building on this result, a theoretical framework for the analysis of such phenomena is developed. This analysis indicates that sensor drift is caused by the slow annealing of quenched-in non-equilibrium oxygen-vacancy donors as MOX gas sensors are operated at moderate temperatures for prolonged periods of time. Most interestingly, our analysis predicts that sensor drift in n-type MOX materials can potentially be mitigated or even suppressed by doping with metal impurities with chemical valences higher than those of the core metal constituents of the host crystals.
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Moos, Ralf, Noriya Izu, Frank Rettig, Sebastian Reiß, Woosuck Shin, and Ichiro Matsubara. "Resistive Oxygen Gas Sensors for Harsh Environments." Sensors 11, no. 4 (2011): 3439–65. http://dx.doi.org/10.3390/s110403439.
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Plata, Desirée L., Yadira J. Briones, Rebecca L. Wolfe, et al. "Aerogel-platform optical sensors for oxygen gas." Journal of Non-Crystalline Solids 350 (December 2004): 326–35. http://dx.doi.org/10.1016/j.jnoncrysol.2004.06.046.
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Suematsu, Kouichi, Takanori Honda, Masayoshi Yuasa, Tetsuya Kida, Kengo Shimanoe, and Noboru Yamazoe. "Effect of Foreign Metal Doping on the Gas Sensing Behaviors of SnO2-Based Gas Sensor." Advanced Materials Research 47-50 (June 2008): 1502–5. http://dx.doi.org/10.4028/www.scientific.net/amr.47-50.1502.
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Recently, we have proposed some theoretical models, power laws and effect of particle shape and size, for semiconductor gas sensors. The models show that a depletion theory of semiconductor can be combined with the dynamics of adsorption and/or reactions of gases on the surface. In the case of SnO2, the relative resistance (R/R0) is proportional to PO 2 n, where n is a constant value (n=1/2) on oxygen partial pressure. In addition, carrier concentration in SnO2 influences depth of the depletion. In this study, to experimentally reveal such effects, we tried to control the carrier concentration in SnO2 by foreign doping and examined their electrical resistance and sensor response. Correlations between doping concentration, crystalline size, and partial pressures of oxygen and H2 on the electric resistance are discussed to reveal the material design for semiconductor gas sensors.
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Cervera Gómez, Javier, Jose Pelegri-Sebastia, and Rafael Lajara. "Circuit Topologies for MOS-Type Gas Sensor." Electronics 9, no. 3 (2020): 525. http://dx.doi.org/10.3390/electronics9030525.
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Metal Oxide Semiconductor or MOS-type gas sensors are resistive sensors which can detect different reducible or volatile gases in atmospheres with oxygen. These gas sensors have been used in different areas such as food and drink industries or healthcare, among others. In this type of sensor, the resistance value changes when it detects certain types of gases. Due to the electrical characteristics, the sensors need a conditioning circuit to transform and acquire the data. Four different electronic topologies, two different MOS-type gas sensors, and different concentrations of a gas substance are presented and compared in this paper. The study and experimental analysis of the properties of each of the designed topology allows designers to make a choice of the best circuit for a specific application depending on the situation, considering the required power, noise, linearity, and number of sensors to be used. This study will give more freedom of choice, the more adequate electronic conditioning topology for different applications where MOS-type sensors are used, obtaining the best accuracy.
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van, den Heever TS, L. Hardie G., and J. Perold W. "Zno Nanowire Gas Sensor ith Uv-Light for Improved Sensitivity." International Journal of Nano Studies & Technology 2, no. 1 (2013): 12–16. https://doi.org/10.19070/2167- 8685-130003.
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ZnO nanowires are synthesised on a patterned substrate in order to see the response to different gases. Under ambient conditions the sensor shows very little response to any gas. A UV-light source is used to increase the sensitivity of the sensor by increasing the conductivity of the ZnO nanowires. The UV-light decreases the number of oxygen ions present on the surface of the ZnO nanowires which leads to better sensitivity. The sensor, with the aid of the laser, can distinguish between the different gases that were used, argon, oxygen, carbon dioxide and nitrogen. When a mixture of two gases was used the response fell in between the response of the individual gases. The obtained results are repeatable and consistent over different sensors.
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Ahn, Sanghoon, Kang Woo Chun, and Changkyoo Park. "Long-Term Stability Test for Femtosecond Laser-Irradiated SnO2-Nanowire Gas Sensor for C7H8 Gas Sensing." Photonics 11, no. 6 (2024): 550. http://dx.doi.org/10.3390/photonics11060550.
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In this study, femtosecond (FS) laser irradiation with different laser energy densities of 138, 276, and 414 mJ/cm2 is applied to SnO2-nanowire (NW) gas sensors, and the effect of the FS laser irradiation on the gas sensor response toward toluene (C7H8) gas is investigated. The FS laser irradiation causes oxygen deficiency in the SnO2 NWs and forms SnO and SnOx. Moreover, an embossing surface with multiple nano-sized bumps is created on the SnO2 NW surface because of the FS laser irradiation. The FS laser-irradiated SnO2-NW gas sensor exhibits superior sensing performance compared with the pristine SnO2-NW gas sensor. Moreover, the FS laser energy density significantly affects gas-sensing performance, and the highest sensor response is achieved by the gas sensor irradiated at 138 mJ/cm2. The long-term stability test of the laser-irradiated SnO2-NW gas sensor is performed by comparing fresh and 6-month-old gas sensors in different gas concentrations and relative humidity levels. Comparable gas-sensing behaviors are examined between the fresh and 6-month-old gas sensor, and this verifies the robustness of the laser-irradiated SnO2-NW gas sensor.
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Lin, Liyang, Susu Chen, Tao Deng, and Wen Zeng. "Oxygen-Deficient Stannic Oxide/Graphene for Ultrahigh-Performance Supercapacitors and Gas Sensors." Nanomaterials 11, no. 2 (2021): 372. http://dx.doi.org/10.3390/nano11020372.
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The metal oxides/graphene nanocomposites have great application prospects in the fields of electrochemical energy storage and gas sensing detection. However, rational synthesis of such materials with good conductivity and electrochemical activity is the topical challenge for high-performance devices. Here, SnO2/graphene nanocomposite is taken as a typical example and develops a universal synthesis method that overcome these challenges and prepares the oxygen-deficient SnO2 hollow nanospheres/graphene (r-SnO2/GN) nanocomposite with excellent performance for supercapacitors and gas sensors. The electrode r-SnO2/GN exhibits specific capacitance of 947.4 F g−1 at a current density of 2 mA cm−2 and of 640.0 F g−1 even at 20 mA cm−2, showing remarkable rate capability. For gas-sensing application, the sensor r-SnO2/GN showed good sensitivity (~13.8 under 500 ppm) and short response/recovering time toward methane gas. These performance features make r-SnO2/GN nanocomposite a promising candidate for high-performance energy storage devices and gas sensors.
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Herrmann, Julia, Gunter Hagen, Jaroslaw Kita, Frank Noack, Dirk Bleicker, and Ralf Moos. "Multi-gas sensor to detect simultaneously nitrogen oxides and oxygen." Journal of Sensors and Sensor Systems 9, no. 2 (2020): 327–35. http://dx.doi.org/10.5194/jsss-9-327-2020.
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Abstract. Due to tightened emission limits, the efficiency of exhaust gas aftertreatment systems has to be further enhanced. Therefore, inexpensive and robust NOx sensors are required to be installed not only in automotive exhausts, but also in any other kind of combustion-based application. In this contribution, an impedimetric NOx sensor is presented. The impedance of a functional thick film (KMnO4, manufactured in a screen-printing technique on planar alumina substrates) depends selectively on the NOx concentration in the exhaust but shows a dependency on the oxygen concentration. Therefore, an additional temperature-independent resistive oxygen sensor structure was integrated on the same sensor platform. BFAT (BaFe0.74Al0.01Ta0.25O3−δ (BaFe0.74Al0.01Ta0.25O3−δ) was used for this purpose, and the measurement was conducted in the dc resistance mode. It serves not only to determine the oxygen concentration in the exhaust, but also to correct the oxygen dependency of the NOx sensor.
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Nazrul, Effendy, David Kurniawan Eko, Dwiantoro Kenny, Arif Agus, and Muddin Nidlom. "The prediction of the oxygen content of the flue gas in a gas-fired boiler system using neural networks and rand." International Journal of Artificial Intelligence (IJ-AI) 11, no. 3 (2022): 923–29. https://doi.org/10.11591/ijai.v11.i3.pp923-929.
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The oxygen content of the gas-fired boiler flue gas is used to monitor boiler combustion efficiency. Conventionally, this oxygen content is measured using an oxygen content sensor. However, because it operates in extreme conditions, this oxygen sensor tends to have the disadvantage of high maintenance costs. In addition, the absence of other sensors as an element of redundancy and when there is damage to the sensor causes manual handling by workers. It is dangerous for these workers, considering environmental conditions with high-risk hazards. We propose an artificial neural network (ANN) and random forest-based soft sensor to predict the oxygen content to overcome the problems. The prediction is made by utilizing measured data on the power plant’s boiler, consisting of 19 process variables from a distributed control system. The research has proved that the proposed soft sensor successfully predicts the oxygen content. Research using random forest shows better performance results than ANN. The random forest prediction errors are mean absolute error (MAE) of 0.0486, mean squared error (MSE) of 0.0052, root-mean-square error (RMSE) of 0.0718, and Std Error of 0.0719. While the errors using ANN are MAE of 0.0715, MSE of 0.0087, RMSE of 0.0935, and Std Error of 0.0935.
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Miyata, Shigeru. "Universal Exhaust Gas Oxygen Sensor and Other Sensors for Engine Control." Journal of The Japan Institute of Marine Engineering 39, no. 11 (2004): 759–64. http://dx.doi.org/10.5988/jime.39.759.
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Kim, Seongyul, Sunil Pal, Pulickel M. Ajayan, Theodorian Borca-Tasciuc, and Nikhil Koratkar. "Electrical Breakdown Gas Detector Featuring Carbon Nanotube Array Electrodes." Journal of Nanoscience and Nanotechnology 8, no. 1 (2008): 416–19. http://dx.doi.org/10.1166/jnn.2008.187.
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We demonstrate here detection of dichloro-difluoro-methane and oxygen in mixtures with helium using a carbon nanotube electrical breakdown sensor device. The sensor is comprised of an aligned array of multiwalled carbon nanotubes deposited on a nickel based super-alloy (Inconel 600) as the anode; the counter electrode is a planar nickel sheet. By monitoring the electrical breakdown characteristics of oxygen and dichloro-difluoro-methane in a background of helium, we find that the detection limit for dichloro-difluoro-methane is ∼0.1% and the corresponding limit for oxygen is ∼1%. A phenomenologigal model is proposed to describe the trends observed in detection of the two mixtures. These results indicate that carbon nanotube based electrical breakdown sensors show potential as end detectors in gas-chromatography devices.
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Palmeira, J., L. Lopes, A. J. Silva, P. A. S. Jorge, and A. Oliva. "Optimization of Ormosil Glasses for Luminescence Based Dissolved Oxygen Sensors." Solid State Phenomena 161 (June 2010): 1–11. http://dx.doi.org/10.4028/www.scientific.net/ssp.161.1.
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In the recent years, sol-gel films have been intensively used in optical sensors configurations. Due to its hydrophobic nature, ormosil films have been reported to be a promising supporting matrix for oxygen sensing dyes for measurements in aqueous media. In this work, the impact of the sol-gel host fabrication parameters in the characteristics of the resulting oxygen sensing membranes is thoroughly evaluated. Different combinations of organic-inorganic precursors, with different aging times, were tested as oxygen sensors. All the solution were doped with ruthenium complex Ru(II)-tris(4,7-diphenyl-1,10-phenanthroline) to introduce oxygen sensitivity. Thin films were produced by dip coating of glass slides. The oxygen sensitive films were tested in aqueous phase in equilibrium with different oxygen gas compositions, using a phase-modulation technique. Sensor performance parameters such as Stern-Volmer constant, quenching efficiency and lifetime response are reported. The data obtained clearly indicates that increased aging times and longer organic groups produce sensors with the highest sensitivity to dissolved oxygen. From all sol-gel films produced, the BTEOS:TEOS (1:1) mixture is the most promising for sensor construction.
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Iswanto, Iswanto, Alfian Ma’arif, Bilah Kebenaran, and Prisma Megantoro. "Design of gas concentration measurement and monitoring system for biogas power plant." Indonesian Journal of Electrical Engineering and Computer Science 22, no. 2 (2021): 726. http://dx.doi.org/10.11591/ijeecs.v22.i2.pp726-732.
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Biogas is a gas obtained from the breakdown of organic matter (such as animal waste, human waste, and plants) by methanogenic bacteria in an oxygen-free (anaerobic) state. The biogas produced mainly consists of 50-70% methane, 30-40% carbon dioxide, and other gases in small amounts. The gas produced has a different composition depending on the type of animal that produces it. It is challenging to obtain biogas concentration data because the monitoring equipment is currently minimal. Therefore, this research discusses how to make a monitoring system for biogas reactors. Sensors are installed in the digester tank and storage tank. The installed sensors are the MQ-4 sensor to detect methane gas (CH<sub>4</sub>), MG-811 sensor to detect carbon dioxide (CO<sub>2</sub>) gas, MQ-136 sensor to detect sulfide acid gas (H<sub>2</sub>S), and Thermocouple Type-K to detect temperature. The sensor will send a signal to the control unit in Arduino Mega 2560, then processed and displayed on the liquid crystal display (LCD). The sensor calculation results' accuracy is not much different from the reference based on the sensor readings. The sensor deviation standard is below 5.0, indicating that the sensor is in precision. The sensor's linearity of MQ-4 is 0.7%, the MG-811 is 0.17%, the MQ-136 is 0.29%, and the Type-K Thermocouple is 1.19%. The installed sensor can be used to monitor gas concentration and temperature in a biogas reactor.
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Donker, Nils, Daniela Schönauer-Kamin, and Ralf Moos. "Mixed-Potential Ammonia Sensor Based on a Dense Yttria-Stabilized Zirconia Film Manufactured at Room Temperature by Powder Aerosol Deposition." Sensors 24, no. 3 (2024): 811. http://dx.doi.org/10.3390/s24030811.
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Powder aerosol deposition (often abbreviated as PAD, PADM, or ADM) is a coating method used to obtain dense ceramic films at room temperature. The suitability of this method to obtain ammonia mixed-potential sensors based on an yttria-stabilized zirconia (YSZ) electrolyte that is manufactured using PAD and a V2O5–WO3–TiO2 (VWT)-covered electrode is investigated in this study. The sensor characteristics are compared with data from sensors with screen-printed YSZ solid electrolytes. The PAD sensors outperform those in terms of sensitivity with 117 mV/decade NH3 compared to 88 mV/decade. A variation in the sensor temperature shows that the NH3 sensitivity strongly depends on the sensor temperature and decreases with higher sensor temperature. Above 560 °C, the characteristic curve shifts from exponential to linear dependency. Variations in the water and the oxygen content in the base gas (usually 10% oxygen, 2% water vapor in nitrogen) reveal a strong dependence of the characteristic curve on the oxygen content. Water vapor concentration variations barely affect the sensor signal.
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Roy, Sandip K., Konstantin V. Vassilevski, Christopher J. O'Malley, Nick G. Wright, and Alton B. Horsfall. "Discriminating High k Dielectric Gas Sensors." Materials Science Forum 778-780 (February 2014): 1058–62. http://dx.doi.org/10.4028/www.scientific.net/msf.778-780.1058.
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High temperature gas sensors for the detection of harmful gases under extreme conditions have been demonstrated. Here, we show the detection and selective response of two SiC based MIS sensor structures with HfO2and TiO2high κ dielectric layers to two different hydrogen containing gases. The structures utilise a Pt catalytic gate contact and a high-κ dielectric that was grown on a thin SiO2layer, which was thermally grown on the Si face of epitaxial 4H SiC. The chemical characteristics of MIS capacitors have been studied in N2, O2, H2and CH4ambients at 573K. The data show a positive flatband voltage shift for oxygen and methane with respect to the nitrogen baseline, whilst hydrogen shows a negative shift. The response for the TiO2based sensor is significantly larger than that of the HfO2based device for hydrogen, enabling discrimination of gases within a mixture.
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Platonov, Vadim, Abulkosim Nasriddinov, and Marina Rumyantseva. "Electrospun ZnO/Pd Nanofibers as Extremely Sensitive Material for Hydrogen Detection in Oxygen Free Gas Phase." Polymers 14, no. 17 (2022): 3481. http://dx.doi.org/10.3390/polym14173481.
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The development of safety sensors is an urgent necessity for the successful use of hydrogen in real conditions, which may differ, in particular, by the oxygen content in the surrounding atmosphere. Palladium-modified zinc oxide shows the high sensitivity when detecting hydrogen in air; however, studies of the sensor properties and the operation mechanism of the ZnO/Pd sensor when reducing gases are detected in an oxygen deficient or inert atmosphere have not been effectuated. In this work, we synthesized the ZnO and ZnO/Pd nanofibers by electrospinning and for the first time determined their sensor properties in the detection of CO, NH3 and H2 in different oxygen backgrounds. The microstructure and composition of nanofibers were characterized by electron microscopy, X-ray diffraction, X-ray fluorescent spectroscopy, and X-ray photoelectron spectroscopy. The interaction with the gas phase was investigated in situ by diffuse reflectance IR Fourier transform spectroscopy (DRIFTS). The sensor properties of ZnO and ZnO/Pd nanofibers were studied at 100–450 °C towards CO, NH3 and H2 in the N2/O2 gas mixtures containing 0.0005–20% O2. When detecting CO, a decrease in the oxygen concentration from 20 to 0.0005% in the gas phase does not lead to a significant change in the sensor response. At the same time, when detecting NH3 and especially H2, a decrease in oxygen concentration down to 0.0005% results in the dramatic increase in the sensor response of ZnO/Pd nanofibers. This result is discussed in terms of palladium hydride formation, modulation of the potential barrier at the ZnO/Pd interface, as well as changes in the concentration of donor defects and charge carriers in the ZnO matrix. Synthesized electrospun ZnO/Pd nanofibers are extremely promising materials for sensors for detecting hydrogen in an oxygen free atmosphere.
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Mohammadi, M. R., Mohammad Ghorbani, and Derek J. Fray. "Influence of Secondary Oxide Phases on Microstructural and Gas Sensitive Properties of Nanostructured Titanium Dioxide Thin Films." Advanced Materials Research 47-50 (June 2008): 41–44. http://dx.doi.org/10.4028/www.scientific.net/amr.47-50.41.
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A systematic comparison of single and binary metal oxide TiO2, TiO2-Ga2O3, TiO2-Er2O3 and TiO2-Ta2O5 gas sensors with nanocrystalline and mesoporous microstructure, prepared by solgel route, was conducted. The gas sensitivity was increased by secondary phase introduction into TiO2 film via two mechanisms, firstly through the inhibition of anatase-to-rutile transformation, since the anatase phase accommodates larger amounts of adsorbed oxygen, and secondly through the retardation of grain growth, since the higher surface area provides more active sites for gas molecule adsorption. The binary metal oxides exhibited a remarkable response towards low concentrations of CO and NO2 gases at low operating temperature of 200°C, resulting in increasing thermal stability of sensing films as well as decreasing their power consumption. The calibration curves revealed that all sensors followed the power law ( B gas A S ] [ = ) (where S is sensor response, coefficients A and B are constants and [gas] is gas concentration). The response magnitude of the sensors obtained in this work is superior to TiO2-based sensors reported in previous studies.
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Effendy, Nazrul, Eko David Kurniawan, Kenny Dwiantoro, Agus Arif, and Nidlom Muddin. "The prediction of the oxygen content of the flue gas in a gas-fired boiler system using neural networks and random forest." IAES International Journal of Artificial Intelligence (IJ-AI) 11, no. 3 (2022): 923. http://dx.doi.org/10.11591/ijai.v11.i3.pp923-929.
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<p><span lang="EN-US">The oxygen content of the gas-fired boiler flue gas is used to monitor boiler combustion efficiency. Conventionally, this oxygen content is measured using an oxygen content sensor. However, because it operates in extreme conditions, this oxygen sensor tends to have the disadvantage of high maintenance costs. In addition, the absence of other sensors as an element of redundancy and when there is damage to the sensor causes manual handling by workers. It is dangerous for these workers, considering environmental conditions with high-risk hazards. We propose an artificial neural network (ANN) and random forest-based soft sensor to predict the oxygen content to overcome the problems. The prediction is made by utilizing measured data on the power plant’s boiler, consisting of 19 process variables from a distributed control system. The research has proved that the proposed soft sensor successfully predicts the oxygen content. Research using random forest shows better performance results than ANN. The random forest prediction errors are mean absolute error (MAE) of 0.0486, mean squared error (MSE) of 0.0052, root-mean-square error (RMSE) of 0.0718, and Std Error of 0.0719. While the errors using ANN are MAE of 0.0715, MSE of 0.0087, RMSE of 0.0935, and Std Error of 0.0935.</span></p>
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Sapkota, Raju, Pengjun Duan, Tanay Kumar, Anusha Venkataraman, and Chris Papadopoulos. "Thin Film Gas Sensors Based on Planetary Ball-Milled Zinc Oxide Nanoinks: Effect of Milling Parameters on Sensing Performance." Applied Sciences 11, no. 20 (2021): 9676. http://dx.doi.org/10.3390/app11209676.
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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.
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Wang, Da Yu, and Eric Detwiler. "Electrode dynamic study of exhaust gas oxygen sensors." Sensors and Actuators B: Chemical 99, no. 2-3 (2004): 571–78. http://dx.doi.org/10.1016/j.snb.2004.01.009.
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Liu, Xiaohui, Wei Sun, Luyi Zou, et al. "Neutral cuprous complexes as ratiometric oxygen gas sensors." Dalton Trans. 41, no. 4 (2012): 1312–19. http://dx.doi.org/10.1039/c1dt11777g.
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Souri, M., M. N. Azarmanesh, E. Abbaspour Sani, M. Nasseri, and Kh Farhadi. "An analytical study of resistive oxygen gas sensors." Journal of Physics: Condensed Matter 20, no. 14 (2008): 145204. http://dx.doi.org/10.1088/0953-8984/20/14/145204.
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Evans, John T., Michael P. Sama, Joseph L. Taraba, and George B. Day. "Automated Calibration of Electrochemical Oxygen Sensors for Use in Compost Bedded Pack Barns." Transactions of the ASABE 60, no. 3 (2017): 957–62. http://dx.doi.org/10.13031/trans.12099.
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Abstract. The objective of this study was to develop an automated calibration process for a galvanic cell type oxygen sensor. The manufacturer recommended a two-point calibration at room temperature; however, testing revealed that the response was not linear when both the temperature and oxygen concentrations varied. Thus, additional points were needed to generate a representative calibration equation and to reduce the sensor prediction interval. The calibration process needed to be capable of automatically recording sensor response (voltage) at an array of temperatures and oxygen concentrations. Calibration gases were used to precisely control the oxygen concentration inside a small manifold, and an electronically controlled water bath was used to regulate the sensor and gas temperature. A custom computer program controlled the sampling order and the data collection process. The responses for three sensors were recorded at six temperature (10°C, 20°C, 30°C, 40°C, 50°C, and 60°C) and five oxygen concentration (0%, 5%, 10%, 15%, and 20% O2 absolute) combinations, for a total of 30 measurements per calibration. Calibration data were used to create a second-degree polynomial model with oxygen sensor voltage and temperature as input parameters, which reduced the prediction interval by over 1% O2 for each of the three sensors tested. The resulting prediction intervals ranged between 0.75% and 0.95% O2. Three sensors were mounted in a prototype oxygen probe and tested under controlled conditions to demonstrate the ability to measure oxygen concentration versus depth in a composting environment. Keywords: Aeration, Calibration, Compost, Dairy, Housing, Oxygen.
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Ling, Yan, Yunjiang Yu, Canxin Tian, and Changwei Zou. "Improving the NO2 Gas Sensing Performances at Room Temperature Based on TiO2 NTs/rGO Heterojunction Nanocomposites." Nanomaterials 14, no. 22 (2024): 1844. http://dx.doi.org/10.3390/nano14221844.
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The development of energy-efficient, sensitive, and reliable gas sensors for monitoring NO2 concentrations has garnered considerable attention in recent years. In this manuscript, TiO2 nanotube arrays/reduced graphene oxide nanocomposites with varying rGO contents (TiO2 NTs/rGO) were synthesized via a two-step method for room temperature NO2 gas detection. From SEM and TEM images, it is evident that the rGO sheets not only partially surround the TiO2 nanotubes but also establish interconnection bridges between adjacent nanotubes, which is anticipated to enhance electron–hole separation by facilitating electron transfer. The optimized TiO2 NTs/rGO sensor demonstrated a sensitive response of 19.1 to 1 ppm of NO2, a 5.26-fold improvement over the undoped TiO2 sensor. Additionally, rGO doping significantly enhanced the sensor’s response/recovery times, reducing them from 24 s/42 s to 18 s/33 s with just 1 wt.% rGO. These enhancements are attributed to the increased specific surface area, higher concentration of chemisorbed oxygen species, and the formation of p-n heterojunctions between TiO2 and rGO within the nanocomposites. This study provides valuable insights for the development of TiO2/graphene-based gas sensors for detecting oxidizing gases at room temperature.
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Zhang, Peng, Shuang Cao, Ning Sui, et al. "Influence of Positive Ion (Al3+, Sn4+, and Sb5+) Doping on the Basic Resistance and Sensing Performances of ZnO Nanoparticles Based Gas Sensors." Chemosensors 10, no. 9 (2022): 364. http://dx.doi.org/10.3390/chemosensors10090364.
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Despite potential advantages of metal oxide semiconductors (MOSs)-based gas sensors, the limitation of very high baseline resistance is still unsatisfactory for practical application. By means of element doping, the performance of metal oxide materials used as gas sensors can be optimized. Herein, different cations (Al3+, Sn4+, and Sb5+) doped ZnO nanoparticles were synthesized and used as the acetone sensing materials. Results show that the resistance of sensors based on Sn4+ doped ZnO was significantly reduced (from 5.18 to 0.28 MΩ) at 270 °C without sacrificing the acetone sensing responses. In addition, the gas sensor also exhibited the fast response/recovery time (1/10 s) and great long-term stability. The electron compensation and improved adsorbing oxygen ability for the Sn4+ doped ZnO nanoparticles contributed to the relatively low resistance and enhanced acetone sensing performances.
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Liu, Chih-Yi, Annada Sankar Sadhu, Riya Karmakar, et al. "Strongly Improving the Sensitivity of Phosphorescence-Based Optical Oxygen Sensors by Exploiting Nano-Porous Substrates." Biosensors 12, no. 10 (2022): 774. http://dx.doi.org/10.3390/bios12100774.
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Sensitivity is one of the crucial factors in determining the quality of a fluorescence/phosphorescence-based gas sensor, and is estimated from the measurement of responses (I0/I, where I0 and I refer to the measured optical intensity of a sensor in absence and presence of analyte molecules) at various concentrations of analytes. In this work, we demonstrate phosphorescence-based optical oxygen sensors fabricated on highly porous anodic aluminum oxide (AAO) membranes showing dramatically high response. These sensors exploit the enormous surface area of the AAO to facilitate the effective interaction between the sensing molecules and the analytes. We spin-coat an AAO membrane (200 nm pore diameter) with a platinum-based oxygen sensing porphyrin dye, platinum(II) meso-tetrakis (pentafluorophenyl) porphyrin (PtTFPP), to fabricate a sensor exhibiting I0/I ~400 at 100% oxygen atmosphere. To address the generality of the AAO membrane, we fabricate a separate sensor with another porphyrin dye, platinum octaethylporphyrin (PtOEP), which exhibits an even higher I0/I of ~500. Both of these sensors offer the highest responses as an optical oxygen sensor hitherto reported. SEM and EDS analysis are performed to realize the effect of the increased surface area of the AAO membrane on the enhanced sensitivity.
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Shujah, T., M. Ikram, A. R. Butt, et al. "H2S Gas Sensor Based on WO3 Nanostructures Synthesized via Aerosol Assisted Chemical Vapor Deposition Technique." Nanoscience and Nanotechnology Letters 11, no. 9 (2019): 1247–56. http://dx.doi.org/10.1166/nnl.2019.3011.
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Herein we demonstrate tungsten oxide (WO3 nanostructures based resistive type sensors for hydrogen sulfide (H2S) gas sensing utility. The WO3 dynamic layers have been deposited upon alumina substrates pre-patterned with gold (Au) interdigitated electrodes. For comparative study, two distinct WO3 nanostructures (S-425 and S-450) have been synthesized using Aerosol Assisted Chemical Vapor Deposition (AACVD) technique at varied deposition temperatures i.e., 425 and 450 °C, respectively. The gas detecting properties of both sensors were investigated against varied concentration (0-60 ppm) of H2S gas levels. The electrical resistance of fabricated gas detectors has been observed at DC bias of 5 V and low operating temperature 250 °C. Specifically, when concentration of H2S gas increases from 0-10 ppm, average resistance of the S-425 and S-450 gas sensors was observed to decrease by 96.5% and 97.6%, respectively. In general, the sensing mechanism of gas sensors proposed in this work can be associated with ionosorption of oxygen species over WO3 nanostructured surfaces. However, the significantly enhanced sensing performance of S-450 sensor may be attributed to improved crystallinity in its structure and improved ions adsorption/desorption kinetics at nanorods surface morphology.