Electrospun fibers embedded with microcrystal for optical temperature sensing

Highlights: • PAN fibers embedded with submicron NaYF₄ microcrystal have been prepared. • Hydrothermal synthesis and electrospun methods are adopted to fiber fabrication. • Effective green up-conversion emissions of Er³⁺ are served for temperature sense. • Maximum relative sensitivity reaches to 1.148% K⁻¹ at 303 K in composite fibers. • Bonding of sensitivity and flexibility extends sense-suitable region. -- Abstract: Na(Y_1−x−yEr_xYb_y)F₄/PAN (NYF-EY/PAN) composite fibers have been successfully fabricated by electrospinning method, and sub-micron embedded crystals in the fibers have presented complete hexagonal structure and thermal reaction function. Effective green up-conversion (UC) fluorescence that originated from flexible fibers can be adapted to microdomain non-contact temperature measurement, complying temperature acquisition for complex geometry and active biological tissue without destroying the temperature field. The maximum absolute sensitivity and the maximum relative sensitivity are 0.00446 K⁻¹ at 423 K and 1.148% K⁻¹ at 303 K, respectively. Composite fibers in which crystallites embedded have superior performances of greater stability and higher sensitivity, are served as micron scale special temperature sensor.