Pt100 sensors (Thermal resistance) is used to measure temperature on the basis of the property that substances' own resistance varies with the temperature.The part of Pt100 sensors that is heated（temperataure-sensing element）is made by dual winding of fine wires around the frame made of insulation materials. When there is temperature gradient in the mediums to be measured,the measured temperature is the average temperature in the dielectric layer within the range where the temperature-sensing element is placed.