UC San Diego

For ZnS:Cu-PDMS composites, the high durability and repeatable light emission due to mechanical stimuli shows promise in various sensing and signaling applications as a method of adding functionality without a dedicated external power source. The cause-and-effect relationship between mechanical loading and light emission in the composite has been widely studied, but there are remaining gaps in understanding of the nature of the mechanical interaction between the particles and matrix and how this affects light emission. Simplified experiments of compressive and sliding interaction and visual observations of the particle-matrix interface provide insight into the nature of the physical interactions that lead to luminescence. Light response to variation of tensile loading characteristics, strain and strain rate, as well as well as the sample characteristics of particle size and mix ratios are compared. Finally, a close examination of the evolution of the light and stress response to cyclic tensile loading shows support for the role that stress softening and interfacial separation play in the characteristics of the light response. The improved understanding can help guide efforts to optimize the material for different applications.