A High-Precision Fluorescence Temperature Sensor Based on Er³⁺-/Yb³⁺-Doped KYW₂O₈ Phosphors

A high-precision ratiometric fluorescence temperature sensor was constructed and used to achieve the real-time chip temperature monitoring. Intense green fluorescence signals at 535 and 557 nm were observed in KYW2O8:Er3/Yb3 phosphors at a low energizing power of 1.5 mW. The calibration curve between fluorescence intensity ratio (FIR) of two green fluorescence signals and temperature was built at the temperature range of 253–423 K. The fitted regression coefficient was 0.999. The maximum absolute and relative temperature sensitivity <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${S}_{\text {a}}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${S}_{\text {r}}$ </tex-math></inline-formula> are 0.0115 K<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-{1}}$ </tex-math></inline-formula> at 423 K and 0.0145 K<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-{1}}$ </tex-math></inline-formula> at 253 K, respectively. The temperature measurement error is only ±0.2 K. Six round cyclic heating and cooling tests indicate that the built fluorescence temperature sensor exhibits good repeatability and could realize real time and accurate measurement of chip temperature.