High-Temperature Piezoelectric Microphones for Aft-Engine Noise Measurement

The Interdisciplinary Consulting Corporation (IC2) proposes the development of an instrumentation-grade, robust, high-temperature piezoelectric microphone for model-scale ground test and full-scale static engine test applications. The goal of this research is to extend the operating temperature range of IC2’s piezoelectric microphones and dynamic pressure sensors using advanced microelectromechanical systems (MEMS) fabrication and packaging techniques to enable wide-band performance and full NIST-traceable calibration at targeted operating frequencies. The resulting fully calibrated sensor will thus directly enable quantifiable fluctuating pressure measurements in flows at temperatures up to 600°C (1112°F). The sensor technology is particularly well suited for use in a variety of National Aeronautics and Space Administration (NASA), Department of Defense (DoD), and other industry- and university-owned model- and full-scale engine test facilities by virtue of its robust, reliable, small form factor. The proposed innovation is to extend the operating temperature range of IC2’s recently commercialized piezoelectric MEMS dynamic pressure sensors. These MEMS piezoelectric sensors are capable of high-bandwidth (up to 1 MHz) fluctuating pressure measurement and are supplied with a full magnitude and phase response throughout the entire operating bandwidth determined using IC2’s patented reciprocal calibration method; however, their maximum operating temperature is currently restricted to 85°C due to temperature limitations of the commercial off-the-shelf (COTS) electronics located directly behind the sensor. This proposal seeks to extend the operating temperature of this proven technology to 600°C (1112°F) by implementing changes to the device structure, electronics, and packaging while maintaining the necessary bandwidth and resolution to enable accurate, quantitative measurements in model- and full-scale engine test applications.