4. Characteristics and influencing factors

4.1 Some theoretical elements

Most gas detection methods rely on the interaction between a gaseous medium and a solid (or liquid, in the case of electrochemistry). The gas to be detected must therefore come into contact with the solid: to do this, it must pass through a number of media protecting the sensitive element. The detection head assembly, as seen previously, comprises a filter, a sinter, a free space, and finally the sensitive element on which the gas will react, after adsorption (example figure 7 ). The species formed by the reaction then desorb and diffuse into the open air, crossing the previous barriers...