Innovative coaxial high-temperature thin-film sensor with core–shell structure surpassing traditional multilayer films

High-temperature thin-film sensors (TFSs) often suffer from inadequate tolerance to elevated temperatures. In this study, an innovative approach is presented to fabricate in situ integrated TFSs with a core–shell structure on alloy components using coaxial multi-ink printing technique. This method replaces traditional layer-by-layer (LbL) deposition and LbL sintering processes and achieves simplified one-step manufacturing. The coaxial TFS includes a conductive Pt core for conducting and sensing and a dielectric shell for electrical isolation and high-temperature protection. The coaxial Pt resistance grid demonstrates excellent high-temperature stability, with a resistance drift rate of only 0.08%·h⁻¹ at 800 °C, significantly lower than traditional Pt TFSs. By employing this method, a Pt thin-film strain gauge (TFSG) is fabricated that boasts remarkable high-temperature electromechanical properties. This effectively addresses the problem of sensitivity degradation experienced by traditional LbL Pt TFSGs when subjected to high temperatures. We demonstrate the system integration potential of the technique by printing and verifying the functionality of a long-path thin-film resistance grid on turbine blades, which can withstand butane flame up to ~ 1300 °C. These results showcase the potential of core–shell structure of the coaxial TFS for high-temperature applications, providing a novel approach to develop high-performance TFS beyond traditional multilayer structure.