3D-printed Gd3NbO7:Yb3+, Tm3+ remote temperature sensor with high sensitivity for industrial and biological applications

In the present research work, a temperature sensor was manufactured combining an optically active Gd 3 NbO 7 :Yb 3+ , Tm 3+ powder with a 3D-printed probe UV photo-curable resin. The sensor was immersed in two different fluids of high relevance for industrial and biological applications: 2-propanol and water. The excitation was carried out with a cw laser at 700 nm, varying the temperature in the 21.0–50.0 °C (294.2–323.0 K) range. In the case of 2-propanol, the radiative emissions of Tm 3+ , at 1626 and 1436 nm (corresponding to the 3 F 4 → 3 H 6 and 3 H 4 → 3 F 4 transitions, respectively), were studied through the luminescence intensity ratio (LIR) approach. For the temperature sensor situated in water, because of the emission at 1436 nm cannot be detected due to the water absorption, the emission at 831 nm ( 3 H 4 → 3 H 6 transition) was registered. In both media, the relative thermal sensitivity ( S r ) and the temperature sensor uncertainty were evaluated. For the temperature sensor in 2-propanol a maximum S r value of 2.15 % K −1 was obtained at 22.8 °C (296.0 K), with an uncertainty of 0.5 K. For the temperature sensor in water, the values were 2.6 % K −1 and 0.2 K for the maximum S r at 49.4 °C (322.6 K) and the uncertainty, respectively. The results obtained are high promising for remote temperature sensing in industrial and biological applications. It is worth noting that all the analyzed emissions correspond to non-thermally-coupled levels (TCLs). To the best of our knowledge, this is the first time that these Tm 3+ non-TCLs have been investigated as a function of the temperature for remote sensor purposes. Moreover, it must be noted that the temperature sensor has been manufactured by 3D printing, wich it is a novelty.