Self-recoverable and cyclically stable near-infrared mechanoluminescence for dual-mode mechanics visualization and biomechanics detection

Mechanoluminescence (ML) materials have shown widespread application prospects in various fields like structural health monitoring, biomechanics sensing, wearable electronics, passive displaying and imaging. However, very limited ML materials can emit near-infrared light, and most of the ML materials need a precharging process, which severely restrict the practical operability. In this work, the attractive near-infrared ML (NIR-ML) of a transition metal ion-doped gallium, SrGa12O19:Cr3+, is reported. This material exhibits selfrecoverable and cyclically stable NIR-ML, overcoming the pre-charging and degradation limitations in the conventional systems. Through the study of thermoluminescence, cathodoluminescence and triboelectric properties, it is proved that the ML performance mainly comes from the electron bombardment process induced by the interfacial triboelectrification. Moreover, a self-activation strategy is designed to further enhance the NIR-ML intensity about 250 times, based on which the dual-mode mechanics visualization and biomechanics detection applications are achieved.