摘要 |
In a device for sensing gases, such as hydrogen, carbon monoxide, ethylene or hydrogen sulphide, in air, a material 1 has one end coated with a layer 2 for catalysing a desired reaction with the production of heat and thus a temperature differential between the end of the material, and the sensor is arranged to produce a voltage in response thereto by the Seebeck effect. Material 1 may be an oxide semiconductor, e.g. tin dioxide, vanadium pentoxide, chromic oxide, or barium titanate, or are usable with sulphide present, e.g. molybdenum disulphide. <IMAGE> |