Persistent Photoluminescence and Mechanoluminescence of a Highly Sensitive Pressure and Temperature Gauge in Combination with a 3D-printable Optical Coding Platform

<p><span>Distinct types of luminescence that are activated by various stimuli in a single material offer exciting developmental opportunities for functional materials. In this study, we introduce a versatile sensing platform that exhibits three types of luminescence: photoluminescence (PL), persistent luminescence (PersL), and mechanoluminescence (ML), which enables the sensitive detection of temperature, pressure, and force/stress. The developed Sr₂MgSi₂O₇:Eu²⁺/Dy³⁺ material exhibits a linear relationship between ML intensity and force, and can be used as an ML stress sensor within the 3&ndash;30 N range. Additionally, the full width at half maximum (FWHM) value of the PL emission band and the PL lifetime of this material are remarkably sensitive to changes in temperature, with values of approximately 0.05 nm/K and 1.29 %/K, respectively. This study demonstrated the use of PersL for sensing pressure for the first time, along with its long-lasting (seconds) lifetime as a manometric parameter. The developed material functions as an exceptionally sensitive triple-mode visual pressure sensor; specifically it exhibits: i) a sensitivity of approximately &minus;297.4 cm^&minus;1/GPa (8.11 nm/GPa) in bandshift mode, ii) a sensitivity of ~272.7 cm^&minus;1/GPa (14.8 nm/GPa) in bandwidth mode, and iii) a sensitivity of 42 %GPa^&minus;1 in PL-lifetime mode, which is the highest value reported to date. Notably, anti-counterfeiting, night-vision safety-sign, 8-bit optical-coding, and QR-code applications that exhibit intense PersL were demonstrated by 3D-printing the studied material in combination with a polymer.</span></p>