In Situ Cold-Junction Compensation Strategy for Semiconductor Thin-Film Thermocouples Based on a Pt Thin-Film Resistance Temperature Detector

Semiconductor thin-film thermocouples offer significant advantages for in situ temperature monitoring in advanced engineering equipment. However, the absence of a reliable cold-junction temperature compensation methodology has constrained their practical deployment. This study proposes an in situ cold-junction compensation strategy based on a Pt thin-film resistance temperature detector (RTD), wherein the Pt thin-film RTD is conformally integrated with an ITO–In2O3 thin-film thermocouple via sputtering and printing processes, enabling precise acquisition of cold-junction temperature without external temperature control apparatus. The fabricated Pt thin-film RTD exhibits a coefficient of determination of 0.99995 over the temperature range from ambient to 300 °C, with a temperature coefficient of resistance of 3810.09 ppm/°C, a maximum fitting error of merely 1.02 °C, repeatability precision superior to 1.46 °C, temperature resolution better than 0.2 °C, and a long-term drift rate as low as 0.006%/h. Under simulated practical operating scenarios, the RTD demonstrates superior thermal tracking performance relative to surface-mounted thermocouples. Conformal device fabrication is further realized on the curved surface of a turbine blade, where the RTD maintains characteristics consistent with those on planar substrates, and effective compensation up to 124 °C is achieved in butane flame thermal shock experiments. This strategy overcomes the limitation of conventional compensation methods to planar substrates, furnishing a reliable solution for high-precision in situ temperature monitoring on curved structures of hot-section components via semiconductor thin-film thermocouples.