Method to detect and to analyse gases, in particular to prevent fire

1. A method for the detection and analysis of gas or vapour, applicable to the prevention of risks due to combustion and comprising controlling the medium to be protected by an elementary sensitive unit including an organic semiconductor element the conductivity of which changes in the presence of the gas or gases and/or vapours to be controlled, wherein the organic semiconductor belongs to one of the following groups : - aromatic amines or polyamines salifyed or not, -- indophenols, - phenolic derivatives containing or not nitrogenous functions and/or carboxylic groups, - aromatic azo or diazo derivatives containing or not other types of nitrogenous groupings, - amino acids, - polypropylenes or polyvinyl-pyridine as donor polymers, and wherein the organic semiconductor is subjected to a preparation with solutions or atmospheres having variable oxidation levels. On utilise comme élément de détection un semi-conducteur organique du groupe comprenant notamment: les dérivés quinoniques, les amines, les indophénols, les dérivés phénoliques et azoïques, les amides, les aminoacides, les polymères donneurs, les complexes organiques à transfert de charge à polymère donneur.