Visually encoded mechanoluminescence through hierarchical structuring with microscale patterns and nanoscale features

Mechanoluminescence (ML), with its mechano-optical properties, is promising in electronics, photonics, and advanced sensing technologies. However, current thin-film mechanoluminescent devices can hardly provide any pixelated force information attributed to the bottlenecks of their low overall light emission efficiency and poor luminescent contrast. This prevents mechanoluminescent devices from advancing further to full-fledged programmable visual force sensors. Here, we show hierarchical multiscale structures enhanced mechanoluminescent force sensors that leverage the stress-light interaction of multiscale-structured arrays to achieve user-defined pixelated force sensitivity on a uniform ML membrane, delivering a high-resolution output of 637 pixels per inch (PPI). Combining stress localization from the microscale structures and light extraction enhancement from the nanoscale patterns, the ML force-sensing membrane produces a dynamic contrast pattern at 521 nm using a single light-centering material with 366% of light intensity comparing to the bare film. The further demonstration of such multiscale-structured ML in creating force-sensitive counterfeits showcases its potential in developing pixelated and programmable force-light interaction systems.