A Dual-Scale Porous Architecture with Anisotropic Mechanoluminescence for Flexible Sensing

Mechanoluminescence (ML) materials, which convert mechanical stimuli into optical signals, hold great promise for applications in flexible sensing and human-machine interfaces. However, conventional dense or randomly porous composite structures often suffer from uniform stress distribution, limited emission intensity, and a lack of directional selectivity. In this work, we propose and fabricate a dual-scale porous copper-doped zinc sulfide/polydimethylsiloxane (ZnS:Cu/PDMS) composite architecture featuring both micron-sized pores and aligned through-holes. Finite element analysis, mechanical characterization, and force-light synchronized measurements reveal that the dual-scale architecture promotes stress redistribution and strengthens the ML response, particularly under radial compression. Compared with dense and single-scale porous counterparts, the dual-scale porous composite exhibits enhanced ML intensity and sensitivity, together with a distinct direction-dependent luminescent response under axial and radial loading. Leveraging this anisotropic emission, its potential in various application scenarios is demonstrated, including bimodal flexible sensing, programmable pattern display, and direction-dependent information encoding. This study provides an effective structural design strategy for developing advanced ML materials and devices with high performance and directional recognition capabilities.