High‐Temperature Gas Sensors for Harsh Environment Applications: A Review

Abstract

This review paper introduces various types of gas sensors operating at high temperatures and their mechanisms, which can provide solutions to gas sensor selection for harsh environment application. Most of the gas sensors are found to be functioning at moderate operating temperatures (<400°C) and only a few reports are available, which highlight gas-sensing performance above 400°C. Therefore, the selection of a more reliable high-temperature gas sensor is necessary and advantageous for applications in areas such as agricultural waste processes (such as pyrolysis processes), military facilities, nuclear power plants, and automobile industries. In this paper, three major parts have been conducted to address the importance of high-temperature gas sensors and provide strategical solution for gas sensor selection. First, we have highlighted the application scenario and the sensing mechanism of various gas sensors operating at high temperature. Additionally, factors that affect sensing performance at moderate operating temperature have been investigated. Secondly, we have discussed the effect of material compositions, morphology of the nanostructures, and the use of dopants on sensing performance of high temperature gas sensors. Meanwhile, the catalytic nature of the sensing layer and temperature effect on chemisorption in oxide-based sensors have been discussed meticulously. Lastly, future challenges including factors affecting various sensor performance, selection, and preparation of sensing materials operating at higher temperatures are explored systematically.

Flexible terahertz photonic light-cage modules for in-core sensing and high temperature applications

“…Note that the maximum temperature reached is well above the melting temperature of plastics and resins, but significantly below the 1400 • C which the ceramic light cages can potentially withstand, due to inherent difficulties associated with installing and safely using high-temperature sources within our university's terahertz laboratory. Nevertheless, we believe the present experiments are a valuable proof-of-concept starting point for showing the viability of using ceramics as the cladding material for modular antiresonant terahertz waveguides and sensors in harsh environments 56 -which might include simple tubes, but which in the specific case of the THzLC also allows direct access to the guiding core as discussed.…”

“…We now demonstrate the potential of using the ceramic light cages as sensors operating at higher temperatures than those allowed by conventional 3D printing polymer-based materials, which typically deform or melt at temperatures close to 150-200 • C. Operating waveguides at extremely high temperatures has applications in optical sensing within harsh environments, 56 which in the context of terahertz radiation allows, for example, remote monitoring of gases (e.g., H 2 O, CO) inside gasifiers 57 and furnaces, 58 with implications for industrial process control. Our modified experimental setup for measuring the temperature-dependent terahertz spectrum is shown in Fig.…”

Nanocomposites for Electrochemical Sensors and Their Applications on the Detection of Trace Metals in Environmental Water Samples

“…Sensors reproducibility and repeatability, represented as an inter-day and intra-day precision, is one of the most important parameters to consider whilst assessing the performance of a sensor [ 69 ]. Equally, the ability of the sensor to withstand long operational hours under hostile environments is monitored [ 70 ]. Nanosensors often retain their compact structure even after operating repeatedly for a long time period without a significant decrease in the performance, as opposed to traditional sensors that appear to degrade in performance when used for a long time under hostile environments [ 71 ].…”

Selectivity in trace gas sensing: recent developments, challenges, and future perspectives

“…During the last decade, several review articles discussed the gas sensors specific to the type of sensors, 1–3 sensor with different materials, 4–12 and the diversity of technologies used, 13–17 or specific to a particular application. 18–23 Among all available techniques/sensors, the performance of the spectroscopic technique (mostly absorption-based techniques) in trace gas sensing is convincing in more excellent selectivity. 16,24,25 It is noteworthy that MOS gas sensors offer high sensitivity even below ppm or less and are the most investigated group of sensors.…”