A predictive mechanoluminescence transduction model for thin-film SrAl2O4:Eu2+, Dy3+ (SAOED) stress sensor

This paper proposes a phenomenological stress-optics transduction model for predicting mechanoluminescence (ML) light intensity from a thin-film ML coating sensor subjected to in-plane stresses. Recent findings on the considerable effects of persistent luminescence (PL) decay on ML phenomena (Rahimi MR, Yun GJ, Doll GL, Choi JS. Opt Lett 2013;38:193235) have motivated the incorporation of critical factors (i.e. strain rate, stress-free PL decay time interval, photoexcitation time, instantaneous PL decay rate, etc.) into a predictive ML transduction model. In the proposed model, the total ML + PL light emission is subdivided into a net ML emission, stress-free PL decay, and additional stress-induced PL decay. These are separately modeled and combined on the basis of interaction of the ML phenomena with PL decay and the effects of strain rates and PL decay time intervals. Predictions by the proposed model were found to agree well with experimental results. The relative total ML + PL light intensity was also proven to be linearly proportional to the mechanical strain energy. The proposed predictive model can be broadly used in the design of ML sensing film and in applications for the calibration process.