Abstract: A new micro-electro-mechanical system(MEMS) thin-film temperature sensor is proposed for the intelligent sensing in hydraulic systems, which has a small size and high temperature measurement accuracy to realize the accurate sensing of fluid temperature signals. A new temperature measurement material system based on polymer-metal-ceramic materials is developed. At the same time, a multi-node three-dimensional array electrode structure is innovatively proposed. For the problem of deposition of thermoelectric thin films on three-dimensional curved polymer substrates, the graphical transfer of thin films on curved substrates is realized based on MEMS magnetron sputtering technology. The test results show that the prepared multi-node type thin film temperature sensor can achieve a sensitivity factor of 42 μV/℃ in the range of-60-200 ℃, a temperature time drift rate of 0.012 ℃/min, a repeatability error of 0.32%, a maximum hysteresis of 1.3% and a full scale error of less than 0.5% FS in the static test from-60-100 ℃. In the comprehensive performance test, the sensor still has a high temperature resolution under the impact of high-speed hot airflow, and can work normally for a long time in different working materials for more than 24 h, which can meet the demand of temperature measurement for a long time to maintain the sealability and stability in the actual hydraulic system.

Key words: hydraulic system, thin film thermocouple, multi-node structure, curved thin film formation, performance study