Thin-Film Thermocouple for High-Temperature Gas Turbine Applications

Introduction: Thin-film thermocouples have become crucial in modern temperature sensing and monitoring applications across various industries. In comparison with wire thermocouples, which have the disadvantages of being bulky, slow to respond to temperature changes, and less suitable for integration into compact or complex systems, thin-film temperature sensors offer high accuracy, rapid response times, and versatility, making them indispensable tools for precise temperature measurement in a wide range of environments and applications. The goal of this study is to discuss the advantages of thin-film thermocouples in comparison with other temperature monitoring systems, including wire thermocouples, particularly in the harsh environment of gas turbine engines, where it is necessary to accurately monitor the surface temperature of turbine blades for structural health monitoring of the propulsion system. Methods: This study is a review of recent literature on thin-film thermocouples, specifically focusing on gas turbine applications for structural health monitoring of engine components, published over the last few years. Results: The review summarizes the studies on thin-film metal thermocouples and thin-film ceramic thermocouples to build a comparative understanding of their performances. Discussion: This comparative study on process parameters for sensor fabrication, substrate selection, maximum operating temperature, sensitivity, and drift rate examines the limitations of metal thin-film thermocouples and the advantages of ceramic thin-film thermocouples. Conclusion: The review article concludes that the thin-film indium-oxide-based ceramic thermocouple has a higher operational temperature capability without degradation and, therefore, performs better than the metallic wire thermocouple.