Cr 3+ ‐Nd 3+ ‐Yb 3+ Co‐Activated NIR I to NIR II Mechanoluminescence Toward Biomechanics Detection

ABSTRACT Near‐infrared (NIR) mechanoluminescence (ML) holds significant promise for in vivo biomechanical detection and imaging due to its self‐powered excitation and self‐recovery capabilities. However, its broader application remains constrained by the limited availability of suitable ML materials and the narrow spectral range of NIR emission. In this study, we report the Y 3 Ga 5 O 12 (YGO): Cr 3+ , Nd 3+ , Yb 3+ /polydimethylsiloxane (PDMS) NIR‐ML composite with broadband NIR emission tunable from 600 to 1100 nm, covering both the NIR‐I and NIR‐II windows. The ML of composite device is driven by an interfacial triboelectric effect arising from the mechanical interaction between the inorganic particles and the polymer matrix. Comparative studies on photon penetration through biological tissues reveal that co‐doping with Nd 3+ and Yb 3+ markedly enhances tissue penetration depth. Specifically, the luminescence decay rate in biological tissues is reduced by 20.8% relative to Cr 3+ single doping, indicating improved optical persistence and signal transmission. These findings demonstrate the potential of full‐spectrum NIR‐ML devices for high‐resolution, deep‐tissue biomechanical sensing and imaging. This work provides a generalizable design strategy for the development of broadband NIR‐ML materials tailored for in vivo mechanical diagnostics.