Synthesis of Upconverting Nanoparticles for Temperature Sensing Applications

Abstract

Lanthanide-doped nanoparticles have been increasingly gaining attention as possible contrast agents due to their unique upconversion luminescence properties. The luminescence of certain emission bands from NaYF4 :Er3+/Yb3+ nanoparticles are also temperature dependent, and can be used as a ratiometric temperature sensor by monitoring the green-to-red emission ratio. The objective of this study was to reproducibly synthesize NaYF4:Er3 +/Yb3+ nanoparticles, use them to create a thin film on a glass surface, and visualize temperature changes on this coated surface. Nanoparticles were prepared via thermal decomposition at 300° C, underwent an acid treatment process to remove the oleate ligands from their surfaces, and were introduced to glass slides that had been functionalized with carboxyl groups. The temperature of the coated glass slide was varied, and images taken using a CCD camera were used to construct the green-tared emission ratio, which showed a linear trend with respect to increasing temperature.