Multimodal Upconversion Luminescence Temperature Sensors NaYF4:Yb,Er,Tm for Biological Applications

NaYF4:Yb3+/Er3+/Tm3+ particles are synthesized in the form of rods with dimensions of 0.21 × 0.77 μm. They exhibit upconversion luminescence in the visible and near-infrared spectral ranges when irradiated at a wavelength of 980 nm. The possibility of using them as multimodal luminescent sensors with temperatures in the range of 250–350 K is shown ratiometrically, based on the emergence of spectral bands at wavelengths of 525, 545, 655, 700, and 805 nm, of particular interest for biological applications.