Implantable Brain–Machine Interface for Olfactory Neural Regulation in Bioelectronic Nose: A Review

Olfaction is not only a chemical sensing system but also a neural functional module highly coupled with emotions, memories, and value judgments. Due to the unique direct cortical projection structure of the olfactory pathway, its damage cannot be fully restored through drugs or peripheral repair, leading to the emergence of bioelectronic noses. In recent years, brain–machine interface (BMI) technology targeting the higher olfactory cortex has become an important direction for olfactory reconstruction and artificial olfaction generation. This technology activates regions such as the piriform cortex, amygdala, and orbitofrontal cortex through electrical, biochemical, or optical modulation methods, bypassing the damaged peripheral system to realize the reproduction or substitution of odor perception. The rapid development of technologies such as neural interface materials, wireless recording, optogenetics, closed‐loop stimulation, and deep learning decoding has made it possible for in vivo bioelectronic noses to move from proof‐of‐concept to functional systems. This review systematically summarizes the regulatory basis of olfactory circuits and higher brain regions, in vivo neural recording and stimulation technologies, signal processing and deep decoding methods, typical applications, while proposing future roadmap suggestions, which can promote the advancement of olfactory neural prostheses from basic research to clinical applications.