This Thermosensitive Handle Changes Hue on Contact with the User's Skin
But these levers aren't as one dimensional as sporting a single predetermined pigment, for the chemical properties of the metal used would be altered during manufacturing to produce a heat-responsive effect as soon as the surface is touched. Depending on the temperature of the user's skin, the Thermosensitive Handle can take on a full spectrum of bright neon tints that differ according to the prior placement of the palm and fingers.
Implications - Apart from affording the standard door handle a more stimulating visual appearance, this technology could be used as an indicator of fire inside a building, as internal heat would cause it to flush red. The occupant would thus be warned against using such an exist to evacuate.