NIR dual-mode temperature sensor based on FIR technology in BaYF5: Nd3+/Yb3+

Near-infrared (NIR) temperature sensor based on fluorescence intensity ratio (FIR) has preeminent superiority in biological tissue. Here, NIR region temperature nano-sensors BaYF5: Nd3+/Yb3+ were designed according to the FIR of 4F3/2(I)→4I9/2/4F3/2(II)→4I9/2 stark levels emission of Nd3+ in 850–920 nm and 4F3/2 → 4I11/2/2F5/2 → 2I7/2 from the emissions of Nd3+/Yb3+ in 950–1100 nm, in which the temperature detection of the former (sensor I) is based on the thermal coupling energy levels of Nd3+ while the probe of Nd3+/Yb3+ (sensor II) is non-thermally coupled energy levels. Hence, the sensor I using Boltzmann distribution theory and sensor II fitting of a polynomial were studied for the sensitivity. Furthermore, the temperature sensing performance of sensor I and sensor II of BaYF5: 1%Nd3+/10%Yb3+ under 808 nm were also discussed. It is proved that NIR temperature sensing probes provide the possibility for application of temperature monitoring in bio-tissue.