Recent progress of gas sensors toward olfactory display development.

Olfactory display systems, designed to replicate the human sense of smell, rely on gas sensors that are fast, selective, and reliable. From this perspective, this review highlights recent progress in sensing materials and integration strategies that enable room-temperature operation, rapid response and recovery, and closed-loop control for realistic odor delivery. Advances are classified into three categories: organic, inorganic, and hybrid systems. Organic materials, including conductive polymers and biomolecules, offer tunable selectivity and lightweight flexibility. Inorganic semiconductors, especially metal oxides, provide high sensitivity and durability, though they typically require elevated temperatures. Hybrid architectures, exemplified by M13 bacteriophage–carbon nanotube composites, merge these strengths to achieve superior performance under ambient conditions. Particular emphasis is placed on sensors for ethylene, hydrogen sulfide, hydrogen, acetone, and nitrogen dioxide—gases critical to food preservation, environmental monitoring, and healthcare. Finally, we discuss persistent challenges, such as selectivity under complex conditions, device miniaturization, and closed-loop integration, and propose strategic research directions toward immersive, real-time olfactory display technologies.