Development of micro dual temperature-heat flux sensing probe using Pt Thin film for transient heat measurements up to 1400 °C.

Thin-film heat flux sensors are critical measurement tools in hypersonic wind tunnel aerodynamic thermal environment tests. However, they suffer from limitations such as poor erosion resistance, low operating temperature (<1200 °C), and large size, which affect wind tunnel testing efficiency. In this paper, a Pt thin-film temperature-heat flux sensor (TFT-HFS) is proposed. A 2 mm alumina micropillar was used as the substrate to enable the arrayed fabrication of the TFT-HFS. Meanwhile, an electrohydrodynamic jet printing technique was employed to deposit the protective layer and regulate the stress within the sensitive layer, effectively improving the stability and high-temperature performance of the sensor. The test results show that the TFT-HFS can operate above 1400 °C with a repeatability error less than 1% FS. Under static laser calibration, the measurement error below 1.7% FS and a repeatability error below 0.6% FS. It exhibits a good linear relationship, with a correlation coefficient of R² = 0.993. During the rapid heating test, the heat flux exceeded 3.5 MW/m², the peak temperature reached 1588.2 °C, and the temperature error less than 0.75% FS. Furthermore, the fabricated TFT-HFS demonstrates an ultrafast response time of 0.2 ms. The proposed TFT-HFS provides a feasible and effective approach for high-temperature transient, high spatial-resolution, and high-precision heat flux measurements.