Synthesis and characterization of ZnS:Cu-based mechanoluminescent phosphors for human motion monitoring

This study presents the development and characterization of copper-doped zinc sulfide (ZnS:Cu) based mechanoluminescent composites for human motion monitoring applications. Using a modified hydrothermal synthesis approach, spherical ZnS:Cu particles with core-shell architecture were produced and embedded in PDMS matrix at concentrations ranging from 0.5 to 5.0 wt%. Photoluminescence analysis revealed peak emission at 520 nm with quantum yield reaching 42% at optimal copper doping of 1.0 mol%. The composite films exhibited exceptional mechanical properties with elongation exceeding 600% and selfhealing capability achieving 91.4% strength recovery within 45 minutes. Under dynamic loading, the materials demonstrated dual-regime strain sensitivity with gauge factors of 0.7 (0-150% strain) and 1.81 (150-1000% strain), alongside rapid response times of 8 ms. Environmental stability tests confirmed consistent performance across temperature range of 25-40°C and relative humidity of 45-85%. The sensors achieved motion detection threshold of 0.2 kPa with angle resolution of 5 degrees, demonstrating practical utility for joint movement monitoring through distinct signal patterns corresponding to various body motions.