Mechanoluminescence is the emission of light in response to applied mechanical stress. Mechanoluminescent materials emit photons when subjected to compressive, tensile, or bending forces. In other words,  a mechanoluminescent material directly converts mechanical energy into photons, providing a quantitative link between the amount of applied stress and the optical output—higher stress produces more photons. I

 

In the Mukhina Lab, we work with ZnS crystals doped with Mn (ZnS:Mn). We studied single microcrystals of this material and found that they produce mechanoluminescence under both plastic (bottom left) and elastic deformation (bottom center and right). The elastic regime is especially valuable for force-sensing applications, as the mechanoluminescent process does not destroy the crystal and can be repeated hundreds of times.