It is difficult to selectively detect small amounts of a gaseous analyte in air, and it is particularly important to do so when the location of dangerous chemicals is to be determined.
For example, since World War II, mine detection has been mostly carried out with the help of metal seekers that detect small amounts of metal contained in most mines. As a result of the development of anti-personal mines with less and less metal, the sensitivity of a metal seeker has been enhanced to give alarm for less than one gram of metal. However, at this sensitivity level metal fragments in the ground will block its use in most mined terrain by giving a false alarm.
Another method for mine detection, and narcotics detection, which has been successfully applied, has been the use of trained dogs. But even the best dog can only work for short periods with full attention and with long rest periods in between. Well trained dogs are also very expensive.
It would be desirable to have an apparatus, a system and a method for the selective detection of small amounts of an analyte in air for many applications, e.g. in the process industry for the detection of specific contamination or leakage, in the airport safety control, customs and police work for the detection of narcotics and bombs, and in clearing the terrain of mines and bombs after a war situation.