Investigation on Two Forms of Temperature-Sensing Parameters for Fluorescence Intensity Ratio Thermometry Based on Thermal Coupled Theory.

Abstract

Absolute temperature sensitivity (Sa) reflects the precision of sensors that belong to the same mechanism, whereas relative temperature sensitivity (Sr) is used to compare sensors from different mechanisms. For the fluorescence intensity ratio (FIR) thermometry based on two thermally coupled energy levels of one rare earth (RE) ion, we define a new ratio as the temperature-sensing parameter that can vary greatly with temperature in some circumstances, which can obtain higher Sa without changing Sr. Further discussion is made on the conditions under which these two forms of temperature-sensing parameters can be used to achieve higher Sa for biomedical temperature sensing. Based on the new ratio as the temperature-sensing parameter, the Sa and Sr of the BaTiO3: 0.01%Pr3+, 8%Yb3+ nanoparticles at 313 K reach as high as 0.1380 K-1 and 1.23% K-1, respectively. Similarly, the Sa and Sr of the BaTiO3: 1%Er3+, 3%Yb3+ nanoparticles at 313 K are as high as 0.0413 K-1 and 1.05% K-1, respectively. By flexibly choosing the two ratios as the temperature-sensing parameter, higher Sa can be obtained at the target temperature, which means higher precision for the FIR thermometers.