▎ 摘　　要

NOVELTY - Device comprises at least one carbon nanotube in many layers of graphene, on which at least one molecule is grafted bearing a group G1 reacting with the chemical compound or a precursor of such a group G1. USE - The device or a system is useful for detecting and optionally quantifying many gaseous chemical compounds, where the gaseous chemical compound is volatile organic compounds, hydrogen, carbon monooxide, carbon dioxide, chlorine and chlorine compounds, ammonia, organophosphorated gas, hydrocyanic acid, thionyl chloride, phosphine, tetrahydrofuran, methane and dimethyl methylphosphonate (all claimed). ADVANTAGE - The device: is selective and very sensitive, even at room temperature; is simple to format and cost effective; and has large surface area, which can reach 1500 m2/g and thus ensures a high surface of interaction with the surrounding atmosphere. The carbon nanotubes have very high electrical conductivity. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for: (1) a system comprising at least two devices; and (2) the preparation of the device to detect at least one chemical compound comprising laying at least one carbon nanotube in many graphene layers, on which at least one molecule is grafted bearing a group G1 for reacting with the chemical compound or precursor of such a group G1, on two electrodes, so that the carbon nanotube provides an electrical contact between the electrodes. DESCRIPTION OF DRAWING(S) - The figure shows a schematic representation of the device. Support (1) Electrodes (2) Carbon nanotubes (3) Means to monitor changes in the resistance of the nanotubes. (4)