Device for detection of specific gas - comprises two probes of variable conductance, one of pure nickel oxide one of doped or non-stoichiometric nickel oxide

摘要

Device for detection of gas of the type formed by a semiconductive metal oxide probe the conductance of which varies when it is in contact with a gas, the oxide being connected to an electrical circuit for detecting electrical changes, comprises at least two probes situated in the same enclosure where the gas to be detected is passing. The first probe is made from a metal oxide, the conductance of which changes in one direction when it is in the presence of the gas to be detected. The second probe is made of a metal oxide of which the physico-chemical properties have been altered so as to give uniquely in the presence of the gas a change of electrical conductance opposite to that normally given by this metal oxide, and which, in the presence of gases other than than that to be detected, gives a change of conductance in the same sense as the first probe. Gas specific probes can be prepared.