Catalytic sensor

A measurement circuit for use in a combustible gas sensor, the measurement circuit comprising:

• a catalytically active element in electrical connection with a thermistor network adapted to compensate for the effect of changes in ambient temperature to the resistance of the catalytically active element without compensating for heat lost by thermal conduction from the catalytically active element and wherein the geometric surface area of the catalytically active element is no greater than approximately 0.5 mm2.

A combustible gas sensor comprising:

• a catalytically active element having a geometric surface area no greater than approximately 0.5 mm2 in electrical connection with a measurement circuit, the measurement circuit including a compensator that compensates for the effect of changes in ambient temperature to the resistance of the catalytically active element without compensating for heat lost by thermal conduction from the catalytically active element.

A method of sensing gas comprising the steps of:

• providing a catalytic active element having a geometric surface area sufficiently small such that the effect upon the output of the active element of heat lost from the active element by thermal conduction is relatively small, and compensating for only the effect of changes in ambient temperature upon the output of the active element.