A mechanoluminescent dual-mode sensor based on Nd-ZnO NRs loaded carbonized silk fabric for real-time nocturnal sports monitoring

Flexible wearable pressure sensors exhibit great potential in human activity tracking. Designing visual sensors that integrate active luminescence and motion monitoring is a current research focus. This study proposed a novel five-layer mechanoluminescent piezoelectric sensor (MPS) that synergistically combined the piezoelectricity of Nd-ZnO NRs loaded carbonized silk fabric (CSF) with the luminescent capability of ZnS:Cu/PDMS. A low-temperature hydrothermal method was utilized to incorporate Nd 3 + into the ZnO lattice, while loading the ZnO NRs onto CSF. Nd 3+ was used as a p-type dopant to regulate the piezoelectricity of ZnO, yielding a highly sensitive piezoelectric layer. The resulting MPS exhibited high pressure sensitivity ( S = 27.48 mV/kPa, 0–100 kPa), excellent pressure response (Response time = 150 ms), and outstanding stability (>2400 cycles). Experiments demonstrated that MPS can effectively monitor human joint movement. Due to the introduction of ZnS:Cu, MPS emitted pulsed light which intensity was linearly correlated with the applied stress (R 2 = 0.98). During the nighttime running test, MPS emitted electrical and optical signals corresponding to the bending angles and frequencies of human joints. MPS features visual and electrical dual-mode sensing capabilities, enabling simultaneous monitoring of pressure and strain stimuli to achieve stress visualization. This study provides a feasible approach to developing intelligent sensing systems with active luminescence.