US Patent 7227473 Thermal sensor

A thermal sensor is provided, which is distinguished in that it includes means for removing a deposit on a sensing element of the sensor. In addition, means for detecting the deposit may be provided. The means for removing the deposit are realized by a trigger circuit for the sensing element, which brings about heating of the sensing element. In addition, a reference sensing element may be utilized as well, which is used both for indirect heating and for checking the sensing element. Due to the use of a catalytic layer on the sensing element, a deposit may be removed at relatively low temperatures.