ZnO–SrAl2O4:Eu Nanocomposite-Based Optical Sensors for Luminescence Thermometry

Abstract

Conventional thermometers fail to operate in a variety of medical procedures due to the harsh and sensitive environments required for such applications, and therefore, the development of optical fiber thermometers has gained significant attention. In this study, a ZnO–SrAl2O4:Eu (ZnO–SAO:Eu) nanocomposite has been synthesized by using a CO2 laser, which showed enhanced optical properties and a dynamic range in comparison with the crystalline ones. XRD, EDAX, SEM, and PL spectroscopy investigated the crystalline and optical properties of precursors, and the final nanostructure, and the findings were in agreement with references. Further analysis of the PL spectra in a 0–100 °C range suggests that the optical properties of the ZnO–SAO:Eu nanocomposite show a linear behavior toward temperature alterations. Considering this inter-relation and measuring the decay time for various frequencies helped us calibrate the temperature based on phase angle shift alterations. The curve obtained at 30 Hz frequency exhibits the highest linearity and accuracy (0.33%) due to its relatively high phase shift (60 °C) in the studied temperature range. The fabricated sensor exhibited great sensitivity and repeatability while maintaining an unprecedented structure. Finally, the thermometer’s applicability for future industries was tested by measuring the interior temperature of a dead muscle tissue as it was being heated by a diode laser and it was accompanied by remarkable results. This achievement could make this device a promising addition to the drug delivery science and industry as it could aid the study and optimization of medications that increase the targeted tissues temperature and therefore can be employed in treating tumors that are formed in organic tissues.