GAS OR VAPOUR SENSOR

摘要

A gas or vapour sensor comprises an electrical conductor (1) in contact with material (2) whose electrical resistance varies, under working conditions, in the presence of a gas or vapour to be detected. The electrical conductor (1) carries a current in use to raise the temperature of the material (2) to an operating temperature. A filter layer (4) is supported on and surrounds the variable resistance material (2), the filter layer allowing only a gas or vapour to be dectected to pass to the variable resistance material, whereby a change in resistance of the material is determined by monitoring the voltage across the electrical conductor.