Frequency response analysis of mechanoluminescence in ZnS:Cu for non-contact torque sensors

This paper presents an experimental frequency response analysis of inverse mechanoluminescence (ML) under dynamic cyclic torque excitation in copper doped zinc sulfide (ZnS:Cu) microparticle. The loading rate-dependent hysteresis of the inverse ML, caused by the phosphorescence quenching of ZnS:Cu in response to dynamic cyclic torsional loading, was first compensated for frequency response analysis using the simple heuristic compensation law according to an ad-hoc heuristic hysteresis model. This model characterizes the inverse ML intensity as a function of the rate of the applied torque input. Precision sinusoidal torque waveforms with frequencies ranging from 0.5 to 15 Hz were employed to identify the frequency response functions (FRFs). By estimating the FRFs, we obtained essential design information that indicates the potential of ML for applications in non-contact torque measurement systems.