High temperature resistant thin film thermocouple prepared based on inkjet printing

Thin film thermocouples (TFTCs) are known for their wide temperature measurement range and high precision, showing significant potential in aerospace and steel metallurgy applications. The lack of effective manufacturing techniques has been a major barrier to their mass production. Inkjet printing, a high-quality thin film additive manufacturing process operating outside vacuum environments, offers a viable solution for large-scale practical applications of TFTCs. We successfully fabricated ITO/In₂O₃ high-temperature thin film thermocouples on ceramic substrates using inkjet printing technology. We developed a printable ink with excellent fluid characteristics, suitable for constructing the sensitive layer of the thermocouples. The fabricated sensors exhibited outstanding high-temperature stability and reliability, with a maximum measurement temperature exceeding 800 °C, surpassing the upper limits reported in other inkjet-printed temperature sensors. Continuous operation at 800 °C for 8 h resulted in a low drift rate of 1.53 °C/h. The sensors demonstrated 98.55 % high repeatability and 98.7%FS high accuracy across a wide temperature range, with a maximum Seebeck coefficient reaching 111 μV/°C, superior to most other high-temperature thin film sensors reported in literature. These findings show great potential in enhancing the safety of aerospace engineering equipment and ensuring the quality of products in the steel metallurgy industry.