In vivo multimodal neurochemical interfaces for real-time decoding of brain circuit.

Neurochemical signalling has emerged as a rapid, versatile and indispensable layer of neural computation, operating alongside electrical activity to shape circuit dynamics, behaviour and disease progression. Decoding these signals in vivo requires sensing platforms that combine spatiotemporal resolution, molecular specificity and anatomical compatibility, capabilities beyond those of traditional sampling methods. Electrochemical technologies, from fast-scan cyclic voltammetry to molecular recognition sensors, deliver subsecond temporal resolution without genetic manipulation, whereas optical approaches using genetically encoded indicators achieve cell-specific measurements with high spatial precision. However, most existing implementations provide only a single sensing function, restricting measurements to a passive chemical dimension and limiting comprehensive or causal circuit analysis. Hybrid systems begin to bridge this gap by coupling stimulation and sensing within unified interfaces, enabling richer interrogation of brain networks. Building on this foundation, transformative multimodal platforms fundamentally expand the boundaries of chemical sensing, overcoming limitations in scope, resolution and accessibility, to enable brain-wide, multianalyte and remote operation. In doing so, they elevate in vivo neurochemical sensing to a frontier discipline, offering unprecedented opportunities to map, decode and therapeutically modulate the chemical logic that underlies cognition, behaviour and pathology.