Mechanoluminescence: unveiling the mechanical stress

Abstract

This chapter describes a brief history, classification, mechanism, materials and applications of a fascinating phenomenon called Mechanoluminescence (ML), exhibited by several solid materials in terms of the emission of light upon mechanical stress and physical deformation. Furthermore, the construction and working of numerous experimental techniques and setups are discussed. Commonly known theories state that ML occurs when the trapped charge carriers are de-trapped due to the piezoelectric field upon applied mechanical stress. Due to the direct relation of emitted ML intensity with applied mechanical stress, it is applicable in automotive, turbines, and robotics for stress sensing, visualization of stress distribution in a metal plate, analyzing stress penetration within synthetic bones and joints, detection of invisible defects and cracks in metal assembly, imagining the crack propagation in infrastructure for health diagnosis, etc.