Carbon based materials for printed gas sensors: A comprehensive review

The adverse impacts of industrialization and population growth have heightened the necessity to detect hazardous gases and volatile organic compounds (VOCs). In this regard, the rising demand for wearable, low-cost, and disposable gas sensors has led to considerable attention in exploring carbon allotropes as a sensing layer in the fabrication of printed gas sensors, in view of their tunable physical and chemical features in the presence of target gases. From this perspective, the present appraisal aims to provide an overview of printed gas sensors incorporating carbon allotropes including carbon nanotubes, graphene, and carbon black as sensing layers through various printing techniques on both rigid and flexible substrate types. The sensor performance relying on various factors such as ink formulation, printing technique, substrates, printing passes, and functionalization are examined. Studies involving the combination of carbon material with metals or polymers to enhance sensitivity, selectivity, and other sensor parameters are also considered. Lastly, the present challenges and the future scope of carbon materials in developing low-cost, wearable, and disposable gas sensors for sustainable and highly efficient real-time monitoring of hazardous gases are also detailed.