SiCOI-Based Heat Flux Sensor Working at 1400 ^∘C

Silicon (Si)-based or even silicon carbide (SiC)-based heat flux sensors often experience material degradation or structural failure due to stress at temperatures above 1200 °C. This paper presents the design and fabrication of an advanced transient high-temperature heat flux sensor, by micromachining an air cylindrical thermal insulation-chamber from a sandwich-structure of silicon carbide-on-insulator (SiCOI) over the silicon substrate. The temperature of the sensor at high heat flux is significantly reduced by utilizing the thermal conductivity of SiCOI material, which is much better than that of SOI material. The proposed structure significantly reduces stress under high-temperature conditions, enabling reliable operation in extreme environments. The sensor is mounted on a ceramic baseplate instead of transistor outline (TO) packaging for high-temperature testing and exhibits exceptional performance over conventional designs, achieving a maximum operating temperature of 1400 °C and stable operation under a heat flux of 3.45 MW/m<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> without the need for water cooling. It offers a rapid response time of 0.9 ms and high sensitivity of 42 μV·m<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>/kW. These remarkable features make it a highly competitive solution for detecting heat flux in high-temperature environments.