A hot-film air flow sensor for elevated temperatures.

Area of Science:

• Materials Science
• Sensor Technology
• Microfabrication

Background:

• Characterizing thermal flow sensors at high temperatures presents significant challenges.
• Silicon carbide (SiC) exhibits promising thermoresistive properties for high-temperature applications.

Purpose of the Study:

• To develop and validate a novel packaging and experimental technique for characterizing thermal flow sensors at elevated temperatures.
• To investigate the performance of a 3C-SiC nano-thin film heater for thermal sensing.

Main Methods:

• Fabrication of 3C-SiC on a glass substrate using anodic bonding.
• Investigation of thermoresistive and Joule heating effects in the 3C-SiC film.
• Calibration using a hot-wire anemometer and characterization of air flow sensitivity.
• Testing sensor stability and robustness at temperatures up to 200 °C.

Main Results:

• 3C-SiC demonstrated a high thermal coefficient of resistance (-20720 ppm/K at ambient, -9287 ppm/K at 200 °C).
• The SiC hot-film sensor achieved a sensitivity of 5 mm⁻¹s for air flow.
• The sensor packaging and materials proved robust and stable at high temperatures.

Conclusions:

• The developed technique and 3C-SiC sensor are suitable for high-temperature thermal flow sensing.
• Silicon carbide is a viable material for thermal sensing in harsh environments.
• The robust design ensures reliable performance under demanding conditions.