Advancing Room-Temperature Chemiresistive Gas Sensors: Integrating 3D Nanoporous Chalcogenides, Photo-activation, and Physical AI for Intelligent Sensing Platforms

Room-temperature (RT) chemiresistive gas sensing is essential for low-power, safe, and deployable chemical perception in distributed sensor networks, wearable devices, autonomous systems, and physical artificial intelligence (AI) platforms. Conventional semiconducting metal oxide (SMO)-based sensors have enabled sensitive and scalable gas detection, but their reliance on thermally activated oxygen ionosorption and surface redox reactions often necessitates elevated operating temperatures, leading to high power consumption, accelerated material degradation, and integration constraints. Chalcogenide semiconductors offer a promising alternative because their tunable band structures, surface-sensitive charge transport, reduced dielectric screening, and interfacial charge-transfer characteristics can facilitate gas-induced carrier modulation at reduced temperatures. This review examines RT chalcogenide chemiresistors through four coupled design levels: electronic transduction, structural amplification, photo-activated kinetic control, and intelligent signal interpretation. We first discuss adsorption-induced charge transfer, gas–surface interactions, and heterointerface modulation as the electronic foundations of RT sensing, and then summarize three-dimensional chalcogenide architectures that increase surface area, edge-site exposure, diffusion, and transport pathways. Photo-activation is highlighted as a nonthermal strategy for accelerating response and recovery, enabling visible-light operation, and improving photon utilization. Finally, we distinguish experimentally demonstrated machine-learning-assisted chalcogenide sensing from the additional sensing–decision–action integration required for physical AI.