High-performance ratiometric optical oxygen sensor fabricated via 3Dprinted silicone for biomedical applications

• A new design of ratiometric optical oxygen sensors demonstrates considerable potential for applications across medical, environmental, and industrial fields. • This research introduces an innovative fabrication method using silicone-based 3D printing technology to develop such sensors. • The silicone matrix's biocompatible nature and the sensor components' high performance are a significant step toward integrating additive manufacturing and optical sensing in developing reliable, miniaturized biomedical sensors for future healthcare technologies. A new design of ratiometric optical oxygen sensors demonstrates considerable potential for applications across medical, environmental, and industrial fields. These sensors are recognized for their high sensitivity, specificity, and resistance to interference from external environmental variables. This research introduces an innovative fabrication method using silicone-based 3D printing technology to develop such sensors. The approach integrates a silicone matrix with oxygen-sensitive dyes, specifically platinum(II) meso-tetrakis(pentafluorophenyl)porphyrin (PtTFPP) or tris(4,7-diphenyl-1,10-phenanthroline), Ru(dpp)₃²⁺, along with reference dyes such as Rhodamine 110 or 7-amino-4-trifluoromethyl coumarin, which are unaffected by oxygen. These phosphorescent compounds are blended into the silicone medium by manual stirring. Using a 405 nm LED as the excitation source, it was verified that the emission spectra of the sensing and reference dyes do not overlap, allowing reliable oxygen detection via a ratiometric method. The effectiveness of the sensors is evaluated by comparing the intensity ratio I N₂/ I O₂ , where I N₂ and IO₂ correspond to the luminescent outputs in nitrogen and oxygen atmospheres, respectively. The sensors embedded with PtTFPP and Ru(dpp)₃²⁺ show linear Stern–Volmer behavior, with sensitivity values of about 69 and 12, respectively. Furthermore, the PtTFPP-based sensor exhibits response times of 41 seconds and 64 seconds for oxygen increase and decrease transitions, respectively, while the Ru(dpp)₃²⁺-based sensor records 45 and 68 seconds for the same changes. This ratiometric sensing approach enhances detection sensitivity and response consistency, minimizing variations caused by fluctuations in light source intensity or fiber optics. Combining ratiometric oxygen sensing with 3D-printed silicone structures provides a robust foundation for developing next-generation oxygen sensor technologies with improved capabilities. The silicone matrix's biocompatible nature and the sensor components' high performance are a significant step toward integrating additive manufacturing and optical sensing in developing reliable, miniaturized biomedical sensors for future healthcare technologies.