Abstract
In the Internet of Things era, flexible and wearable gas sensors are increasingly vital for real-time monitoring in healthcare, environmental safety, and industrial security. These sensors detect hazardous gases at room temperature and seamlessly integrate with clothing and portable devices. The 2D materials, including transition metal dichalcogenides, black phosphorus, MXenes, graphene and its derivatives, and metal-organic frameworks, stand out due to their exceptional electrical, mechanical, and physicochemical properties, such as large surface areas, high carrier mobility, and intrinsic flexibility. This review summarizes recent advancements in designing, fabricating, and applying 2D-material-based flexible gas sensors. It highlights how engineering approaches like defect creation, composite formation, and surface functionalization significantly enhance sensor sensitivity, selectivity, and response times. Comparative performance data across various material families are presented, alongside effective strategies for integrating 2D materials onto diverse flexible substrates such as polymers, textiles, and paper, emphasizing durability under mechanical stress. The review critically addresses current challenges, including large-scale manufacturing, long-term stability, and interference from ambient humidity. Furthermore, it explores innovative solutions like self-healing sensors, artificial intelligence-driven sensor arrays, in situ surface passivation, and multisensor platforms coupled with machine learning algorithms, offering valuable insights for advancing next-generation wearable gas-sensing technologies.