Micro-Strain Responsive Near-Infrared Mechanoluminescence for Potential Nondestructive Artificial Joint Stress...

Recently, joint replacement surgery is facing significant challenges of patient dissatisfaction and the need for revision procedures. In-situ monitoring of stress stability at the site of artificial joint replacement during postoperative evaluation is important. Mechanoluminescence (ML), a novel "force to light" conversion technology, may be used to monitor such bio-stress within tissues. However, this is hindered by ultraviolet-visible ML emission wavelength, low ML intensity, and high strain response sensitivity. Here, by incorporating Sb³⁺ ions into Sr₃Sn₂O₇ crystals, a highly strain-responsive material, with ML originating from intrinsic defect emissions is obtained. The Sr₃Sn_1.98Sb_0.02O_6.99 film produces detectable ML signals under compressive strain as low as 50 µst in the absence of biological tissue. After pre-irradiating with red light through 15 mm of porcine tissue, ML signals can still be detected through the same tissue thickness. Notably, this material enabled real-time stress imaging through 4 mm of porcine skin during mild finger joint bending. This work presents a novel methodological framework and proposes a new mechanism to defect ML. It offers a fresh perspective for designing high-performance ML materials and lays the foundation for innovative research to enhance the functionality of artificial tissues and joints in living organism.