Abstract:Gas sensors are essential for industry and for a wide range of applications. They are for examples applied in public safety, pollution monitoring, and various industrial processes. Among the different gas sensing technologies, semiconducting metal oxide-based gas sensors are the most popular because of their low price, high sensitivity, short response time, high stability and simple operation. In these gas sensors, because gas adsorption has a direct relationship with the surface area of the sensing material, … Show more
“…The reason is that the temperature difference between the shuttle and heater arms was 64 K and the gas pressure was 62 Pa in [ 38 ], but in the current work, the temperature difference and pressure were considered as 37.5K and 387 Pa, respectively. Temperature difference and pressure are two crucial factors significantly influencing the value of Knudsen force [ 2 , 9 , 10 , 11 , 12 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ]. On the other hand, a larger Knudsen force was obtained in the case where only one shuttle-heater pair was simulated, neglecting the coupling effects ( Figure 2 b).…”
Section: Resultsmentioning
confidence: 99%
“…At present, we already have gas sensors such as gas chromatographs and mass spectrometers that can provide a very low limit detection, high accuracy, and selectivity. However, they have problems of large size, complicated structure, high price, and long response time [ 11 , 12 ]. There are commonly used chemiresistive, acoustic, optical, and capacitive gas sensors according to different working principles [ 13 , 14 , 15 , 16 ].…”
Knudsen force generated by thermally driven gas flow in a microscale structure has been used for gas detection and has shown immeasurable potential in the field of microelectromechanical system (MEMS) gas sensors due to its novel sensing characteristics. In this article, the performances of three kinds of Knudsen force gas sensors with improved isosceles triangular shuttle arm structures were studied. In the first design, the top side and right side lengths were equal; in the second, the top side and bottom side lengths were equal; and for the third, the bottom side and right side lengths were equal. A detailed investigation including gas flow, thermal characteristics, Knudsen force, and coupling effects between the shuttle-heater pairs was conducted using the direct simulation Monte Carlo (DSMC) method and the main mechanisms for gas flow presented were almost the same in this work. However, the second design returned the highest Knudsen force performance. The value increased by 42.9% (P = 387 Pa) compared to the Knudsen force of the original square shuttle arm. The results also demonstrate that the coupling effects become weak toward the right with an increase in the number of shuttle-heater pairs.
“…The reason is that the temperature difference between the shuttle and heater arms was 64 K and the gas pressure was 62 Pa in [ 38 ], but in the current work, the temperature difference and pressure were considered as 37.5K and 387 Pa, respectively. Temperature difference and pressure are two crucial factors significantly influencing the value of Knudsen force [ 2 , 9 , 10 , 11 , 12 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ]. On the other hand, a larger Knudsen force was obtained in the case where only one shuttle-heater pair was simulated, neglecting the coupling effects ( Figure 2 b).…”
Section: Resultsmentioning
confidence: 99%
“…At present, we already have gas sensors such as gas chromatographs and mass spectrometers that can provide a very low limit detection, high accuracy, and selectivity. However, they have problems of large size, complicated structure, high price, and long response time [ 11 , 12 ]. There are commonly used chemiresistive, acoustic, optical, and capacitive gas sensors according to different working principles [ 13 , 14 , 15 , 16 ].…”
Knudsen force generated by thermally driven gas flow in a microscale structure has been used for gas detection and has shown immeasurable potential in the field of microelectromechanical system (MEMS) gas sensors due to its novel sensing characteristics. In this article, the performances of three kinds of Knudsen force gas sensors with improved isosceles triangular shuttle arm structures were studied. In the first design, the top side and right side lengths were equal; in the second, the top side and bottom side lengths were equal; and for the third, the bottom side and right side lengths were equal. A detailed investigation including gas flow, thermal characteristics, Knudsen force, and coupling effects between the shuttle-heater pairs was conducted using the direct simulation Monte Carlo (DSMC) method and the main mechanisms for gas flow presented were almost the same in this work. However, the second design returned the highest Knudsen force performance. The value increased by 42.9% (P = 387 Pa) compared to the Knudsen force of the original square shuttle arm. The results also demonstrate that the coupling effects become weak toward the right with an increase in the number of shuttle-heater pairs.
“…That is why since 2000, the development of gas sensors based on 1D structures has become one of the most popular areas of research in the field of gas sensors [ 5 , 86 , 106 , 144 , 145 , 149 , 214 , 215 , 216 ]. If there is an interest only in the performances of 1D-based gas sensors, then I recommend referring to the reviews [ 144 , 204 , 217 , 218 , 219 , 220 , 221 , 222 , 223 , 224 , 225 ], where such information is presented. As with conventional gas sensors, based on nanostructured crystallites, the sensing properties of individual NWs are affected by the NW diameter, the NW synthesis procedure, the feature of surface functionalization, and the reactions that occur on the NW surfaces.…”
This article discusses the main uses of 1D and 2D nanomaterials in the development of conductometric gas sensors based on metal oxides. It is shown that, along with the advantages of these materials, which can improve the parameters of gas sensors, there are a number of disadvantages that significantly limit their use in the development of devices designed for the sensor market.
“…The reaction of oxygen ionic species with reacted gases can change the height of the Schottky barrier to (V 2 ) ( Fig. 2 (b)), which changes the conductivity, and thus the resistance, of the gas sensor [ [26] , [27] , [28] ]. Fig.…”
With the tremendous advances in technology, gas-sensing devices are being popularly used in many distinct areas, including indoor environments, industries, aviation, and detectors for various toxic domestic gases and vapors. Even though the most popular type of gas sensor, namely, resistive-based gas sensors, have many advantages over other types of gas sensors, their high working temperatures lead to high energy consumption, thereby limiting their practical applications, especially in mobile and portable devices. As possible ways to deal with the high-power consumption of resistance-based sensors, different strategies such as self-heating, MEMS technology, and room-temperature operation using especial morphologies, have been introduced in recent years. In this review, we discuss different types of energy-saving chemisresitive gas sensors and their application in the fields of environmental monitoring. At the end, the review will be concluded by providing a summary, challenges and future perspectives.
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