Tm3+-doped upconversion nanoparticles water probing

Abstract

Water probing based on lanthanide-doped upconversion nanoparticles (UCNPs) has aroused great interest due to the advantages of high photostability, short response time, no autofluorescence background, and low toxicity. Compared with widely used Er3+-doped UCNPs, Tm3+-doped UCNPs are not considered as efficient water probes due to the phonon energy mismatch. Here, we demonstrate the water probing based on Tm3+-doped UCNPs with excellent sensitivity and linearity, and reveal that the fractional photon-assisted Förster resonance energy transfer could play a significant role in the mechanism. The recorded sensitivities of up to 6.141%/vol% and 3.932%/vol% were achieved for the hydrogen oxide and deuterium oxide detection. Based on the developed UCNPs, we developed two sensing devices, namely, an UCNPs-coated micro-fiber and UCNPs-embedded silk, for distributed and wearable humidity sensing. Our study opens an unprecedented avenue to develop real-time, high-sensitivity, high-stability, biocompatible water probes serving the fields of cytobiology, pharmaceutics, environmental health and safety, fine chemical industry, and precision agriculture.