Heating films are polyester films on which a conductive pattern is printed. Two silver contacts are connected to each other using graphite. When tension is applied to the foil, the graphite surface is heated. A temperature sensor can be placed on the foil to regulate the voltage.
For example, the film can be attached to the back of a mirror or around a lens to prevent condensation. Furthermore, this foil can of course also be used as a pure heating source for operating instruments, such as a joystick.