Review and Perspective: Gas Separation and Discrimination Technologies for Current Gas Sensors in Environmental Applications

Abstract

Presently, numerous state-of-the-art approaches are being adapted for gas sensing and monitoring. These include hazardous gas leak detection as well as ambient air monitoring. Photoionization detectors, electrochemical sensors, and optical infrared sensors are a few of the commonly widely used technologies. Extensive reviews on the current state of gas sensors have been summarized. These sensors, which are either nonselective or semiselective, are affected by unwanted analytes. On the other hand, volatile organic compounds (VOCs) can be heavily mixed in many vapor intrusion situations. To determine the individual VOCs in a highly mixed gas sample using nonselective or semiselective gas sensors, gas separation and discrimination technologies are highly warranted. These technologies include gas permeable membranes, metal–organic frameworks, microfluidics and IR bandpass filters for different sensors, respectively. The majority of these gas separation and discrimination technologies are currently being developed and evaluated in laboratory-controlled environments and have not yet been extensively utilized in the field for vapor intrusion monitoring. These technologies show promise for continued development and application in the field for more complex gas mixtures. Hence, the present review focuses on the perspectives and a summary of the existing gas separation and discrimination technologies for the currently popular reported gas sensors in environmental applications.

High-Selectivity Laminated Gas Sensor Based on Characteristic Peak under Temperature Modulation

“…), − and changes in working modes. , These studies can change the response amplitude of the metal oxide gas-sensitive material to the target gas so as to optimize the selectivity of some gases. In addition, advanced porous materials, particularly coordination polymers or metal–organic frameworks (MOFs), have been widely studied as novel electrocatalysts for VOC separation. − Crystalline and porous materials known as MOFs are composed of inorganic metal ions and organic ligands, which form a three-dimensional network with nanometer-sized pores. They selectively adsorb gas molecules based on their size, shape, and chemical properties, making them ideal for gas-selective sensing.…”

Programmable and Modularized Gas Sensor Integrated by 3D Printing

“…The comprehensive development of gas detection and analysis systems is important for monitoring atmospheric conditions, safeguarding human health, and ensuring the optimal functioning of electronic instruments. To quantify these imperceptible environmental variables, various gas sensors predicated on distinct detection principles have been extensively researched and employed. − These include electrically transduced gas sensors, acoustic gas sensors, optical gas sensors, thermal gas sensors, electrochemical gas sensors, and gas chromatography, each tailored for specific application scenarios leveraging their unique attributes. − The performances of the gas sensors are principally gauged by the key indicators including response, sensitivity, selectivity, limit of detection, response/recovery time, and stability. , These parameters evaluate the output signal intensity, the proportional response to gas concentration, the specificity for target gas detection, the minimum detectable concentration of the target gas, the time span for attaining a stable output or baseline reading after exposure to or withdrawal from the target gas, and long-term operation capability, respectively. They are profoundly influenced by the configuration of their constituent components, especially from the active material, chamber, and channels with special aerodynamic performance requirements. , Fortunately, these elements are amenable to optimization through geometric modification and can be precisely and efficiently fabricated using 3D printing technologies.…”

SERS sensing chip based on Ti3C2/nano-Au@MA for ultrasensitive amine gas detection

“…[5][6][7] To address the need for monitoring trace amounts of amine gases in eld environments, sensing technologies have garnered considerable attention owing to their advantages, including high environmental adaptability, sensitivity, rapid detection, compact size, and portability. [8][9][10] Several amine gas sensors have been developed and employed, with a predominant focus on electrochemical gas sensing techniques, metal oxide semiconductor sensors, and colorimetric methods. [11][12][13] However, these approaches entail challenges such as poor selectivity and low sensitivity, primarily stemming from the high chemical activity of amine gases.…”