Multiple fluorescence-temperature feedback in Y₇O₆F₉:Er/Yb crystal-embedded polyacrylonitrile fibers

A highly sensitive and flexible, multichannel thermometer prepared by exploiting the emission behaviors of Er³⁺ in Y₇O₆F₉:Er/Yb crystal-embedded polyacrylonitrile fibers is reported. This sensor could be operated at 303-433 K, and the maximum relative sensitivity based thermal-coupling level was 1.285% K⁻¹ at 303 K. More interesting is that the self-calibration could be achieved from the single Er³⁺ emission avoiding the intervention of other calibration tools. Repeatability experiments also confirmed the accuracy and durability of this fabricated material. Further details have been provided to reveal the multi-channel sensing mechanism, in which the green-green emission and red-red emission based thermal-coupling level, and the blue-green emission based non-thermal coupling level are discussed. All the above results showed that the Y₇O₆F₉:Er/Yb crystal-embedded polyacrylonitrile fibers have extraordinary potential in intelligent wearable devices, industrial safety protection, and anti-counterfeiting mark fields.