Thermal conductivity hydrogen sensor: From fundamental principles to smart gas sensing applications

Abstract

Hydrogen is widely recognized as the leading green energy carrier of the 21st century, owing to its diverse production pathways, high combustion energy density, and environmentally benign byproduct: water. However, its wide flammability range (4-75 vol.% in air) and extremely low minimum ignition energy (0.02 mJ) pose significant safety risks across the entire lifecycle of production, storage, transportation, and utilization, necessitating real-time monitoring through highly reliable sensing technologies. Among various hydrogen detection methods, thermal conductivity sensors have attracted considerable attention due to their oxygen-independent operation, broad measuring range, mechanical robustness, and long service lifespan. Despite growing research interest, there remains a notable lack of comprehensive review articles specifically dedicated to thermal conductivity hydrogen sensors (TCHSs) that consolidate the current state of knowledge and guide future research directions. This paper presents a systematic analysis of the working principles and operating modes of TCHSs, introduces key performance parameters, and reviews theoretical models describing the effective thermal conductivity of gas mixtures. The discussion covers representative sensor architectures, gas inlet configurations, and critical environmental factors influencing sensor performance. Furthermore, recent advances and emerging trends are examined, with particular emphasis on smart gas sensing technologies enabled by sensor integration and advanced machine learning algorithms. This study aims to serve as a comprehensive academic reference, offering a clear and structured framework for researchers, particularly those newly entering the field of hydrogen sensing.

Keywords

Thermal conductivity hydrogen sensor / sensing principle / operating mode / structural design / smart gas sensing applications

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