In-field devices for detecting nerve-agent metabolites and mimics in biological and environmental matrices.

Rapid, portable detection of nerve-agent metabolites and safe mimics is essential for exposure assessment, forensic verification, environmental monitoring, and timely clinical intervention. Recent years have seen significant advances in point-of-use platforms, including colourimetric and paper-based assays, electrochemical sensors, enzyme- and biosensor-based approaches, smartphone-integrated devices, and wearable formats, which target metabolites (e.g., alkyl methylphosphonic acids and dialkyl phosphates), protein adducts, and surrogate markers such as cholinesterase inhibition. Nevertheless, analytical challenges (matrix effects, low concentrations in chronic exposures, selectivity for pesticides/industrial organophosphates, and stability under field conditions) remain. This review summarises detection targets, in-field technologies, analytical and biological challenges, and recommendations for translating laboratory prototypes into robust field-deployable systems.