Flat-Package MEMS Fuselage Microphones for External Airplane Fluctuating Pressure Field Measurements – SBIR Phase 1

Contract Number – 80NSSC21C0228 | SBIR Phase 1 | Principal Investigator – David Mills | Project Start Date – 5/19/2021

The Interdisciplinary Consulting Corporation (IC2) proposes to develop an ultra-low-profile, ultra-smooth sensing surface, instrumentation-grade microphone for in-flight aeroacoustics measurements using microelectromechanical systems (MEMS) piezoelectric sensing with backside electrical contacts and advanced packaging technology. This work is aimed at fulfilling the aerospace industry’s need for economically viable sensing technology that meets required metrics for flight testing for a broad class of fluctuating pressure measurement use cases including noise source location, noise shielding effects, noise source interaction effects (such as engine/airframe interactions), boundary layer measurement/characterization, and high-gradient flow investigations; essentially, any on-body fluctuating pressure field problem of interest whether it includes propagating acoustics, hydrodynamic pressure fluctuations, or a combination of both. The proposed flat-pack microphones will be batch fabricated using micromachining technologies to enable low cost per device, tight phase matching, and consistent device performance. Silicon vias will be integrated into the sensor structure to enable backside electrical connection to the piezoelectric ring. The sensors will be mounted into ultra-low profile (≤1.0 mm thick) flat-pack housings along with low-power signal conditioning electronics, analog-to-digital conversion electronics, and custom fairings to enable measurements with minimal disturbance to the flow. The digital data output capability of the microphones may be serialized and converted to an optical signal for transmission through the airplane fuselage, thus eliminating the need to drive analog signals over long cables, the need to penetrate the fuselage with every signal cable, and the need for a lightning arrester for every channel to mitigate the potential impacts of a lightning strike while in flight.

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