Self-powered near-infrared mechanoluminescence for blood oxygen saturation monitoring

Near-infrared mechanoluminescence (NIR ML) materials are gaining attention due to the unique “force-to-photon” conversion ability, offering significant potential for stress sensing, biological imaging, and medical diagnostics. However, current NIR ML materials are facing limitations such as high activation thresholds and poor self-powered emission stability. In this study, we present a self-powered NIR ML material, La 3 Ga 4.9 GeO 14 :0.1Cr 3+ , which exhibits stable emissions under high-temperature heat treatment without requiring external pre-irradiation process. Tuning the Y 3+ /La 3+ ion molar ratio obtained approximately tenfold increased ML intensity, with a low activation threshold ∼1 N. First-principles calculations indicate that Y 3+ substitution induces local lattice distortions, narrowing the bandgap and enhancing carrier mobility (Electron: 193.7 → 485.362 cm 2 V –1 s –1 , Hole: 5.411 → 57.736 cm 2 V –1 s –1 ). This work demonstrates NIR ML technology for non-invasive blood oxygen saturation monitoring based on hemoglobin and oxyhemoglobin (Hb/HbO 2 ) absorption differences, providing insights for expanding NIR ML applications in biomedical imaging. • Self-powered broadband near-infrared mechanoluminescence is achieved through the d - d transitions of Cr 3+ ions, without the need for UV light pre-irradiation. • Substituting La 3+ with Y 3+ significantly enhances the near-infrared mechanoluminescence of Cr 3+ ions, with an increase to approximately 10 times the initial intensity. • The increase in carrier mobility (electrons: 193.7→485.36 cm 2 V –1 s –1 , holes: 5.411→57.736 cm 2 V –1 s –1 ) is the fundamental source of mechanoluminescence enhancement. • A non-invasive blood oxygen saturation monitoring method based on near-infrared mechanoluminescence spectroscopy is proposed, demonstrating its potential application value in biomedical fields.