The resistance value of the conductor changes with temperature. The temperature of the object to be measured is calculated by measuring its resistance value. The sensor constructed by this principle is a waterproof temperature sensor. This sensor is mainly used for temperature in the temperature range of -200-500℃ measuring. Pure metal is the main manufacturing material of thermal resistance, and the material of thermal resistance should have the following characteristics:

(1) The temperature coefficient of resistance should be large and stable, and there should be a good linear relationship between resistance and temperature.

(2) High electrical resistivity, small heat capacity and fast reaction speed.

(3) The material has good reproducibility and manufacturability, and the price is low.

(4) The chemical and physical properties are stable within the temperature measurement range.

At present, platinum and copper, which are most widely used in industry, have been made into standard temperature measuring thermal resistance.