High-Temperature Piezoelectric Pressure Sensors for Hypersonic Flow Measurements

This paper presents a microelectromechanical-system (MEMS) piezoelectric pressure sensor for measurements in hypersonic flows at extreme temperatures (>1000 °C). 700-μm diameter diaphragms are surface- and bulk-micromachined and employ aluminum nitride as the sensing material due to its potential for high-temperature operation. Novelty claims include the following: (1) First demonstration of MEMS piezoelectric pressure sensor to capture hypersonic-flow-specific features in field measurements, including shock waves and second-mode instabilities associated with laminar-to-turbulent transition, (2) Successful audio capture while the sensor is immersed in a butane flame, demonstrating operation at extreme temperatures, and (3) First dynamic pressure sensor to include on-diaphragm thin-film platinum temperature sensors for high-temperature readout.