Remote Luminescent Temperature Sensing Using 3D‐Printed Eu(III)‐Doped Micropolymers at the Tip of an Optical Fiber

Abstract Additive manufacturing offers a novel and versatile approach for fabricating micro‐ and nanoscale structures, allowing direct printing onto the tip of optical fibers. This technology facilitates the miniaturization of existing sensors and the development of new ones, providing exceptional precision and reproducibility. Meanwhile, optical thermometry based on lanthanide luminescence demonstrates significant potential for contactless and remote temperature measurements. This work employs two‐photon polymerization 3D printing to fabricate microstructures at the tip of a multimode silica optical fiber, incorporating the Eu 3+ thenoyltrifluoroacetonate (tta) coordination complex. Temperature sensing measurements are conducted using two different methods: the Luminescence Intensity Ratio (LIR), which utilizes emissions from both the polymer fiber coating and the Eu 3 ⁺ complex, and an RGB colorimetric analysis derived from optical images. The results confirm the successful development of an Eu 3+ ‐doped resin/polymer and temperature evaluation in the range of 296 to 363 K using the returning emission from the fiber tip. A relative sensitivity of 5.0% K⁻¹ is achieved in the LIR method, with exceptional stability of the structure in different solvents and temperatures, showcasing the potential of this integrated approach for high‐performance, miniaturized optical temperature sensing.