3D-Printed polymer microstructures doped with lanthanide ions for ratiometric and lifetime-based luminescence thermometry

Additive manufacturing of temperature-responsive materials presents new opportunities for the development of precise thermal sensors in micro- and nanoscale devices. In this study, we demonstrate the integration of lanthanide ions (Eu³⁺, Tb³⁺, and Sm³⁺) into 3D-printed polymer microstructures for temperature sensing via luminescence. Eu³⁺-doped structures exhibited stable luminescence and enhanced energy harvesting from organic ligands, indicating their high potential for temperature sensing applications. In contrast, Tb³⁺ and Sm³⁺ systems exhibited interference from background fluorescence. Temperature-dependent measurements revealed complementary behavior between the polymer and Eu³⁺ emissions, enabling ratiometric sensing across two distinct temperature ranges. By utilizing luminescence intensity ratio and lifetime analysis, maximum sensitivities of 5.5% K⁻¹ (360 K) and 5.7% K⁻¹ (370 K) were achieved, respectively. These findings position 3D-printed lanthanide-doped structures as robust, sensitive, and remote temperature sensing platforms.