Mineral Insulated Resistance thermometers are a very common form of temperature sensor. It surprises me how often design engineers are not familiar with the product. They may be called Metal clad, MIMS, or simply MI.
Basic design of Mineral Insulated Sensors
The basic Mineral Insulated Resistance Thermometer design has a sensor and conductors inside a metal tube. Insulation is provided by tightly packed Magnesium Oxide powder. The assembly is robust and ductile. Smaller diameters can be easily bent by hand allowing fairly simple installation through very difficult routes. Diameter 6.0 mm and above are more difficult to bend, but can still be routed as required.… Read more