Publications

Kolja Erbacher, Onteru Lokesh, Claire Bourquard, Lixiang Wu, Piotr Mackowiak, Ha Duong Ngo, Martin Schneider-Ramelow, “Characterization of a Piezo-Resistive MEMS Microphone for Aero-Acoustic Measurements”, 2023 Sensor and Measurement Science International (SMSI) Proceedings, AMA: 11 May 2023

Link: C4.4 – Characterization of a Piezo-Resistive MEMS Microphone for Aero-Acoustic Measurements · AMA Science (ama-science.org)

Abstract: This paper presents the packaging and characterization of a piezo-resistive (PR) micro-electro-mechanical system (MEMS) microphone for aero-acoustic measurements with three different mem-brane sizes. The thickness of the square membranes is 5 μm with an edge length of 1900 μm, 2260 μm and 2660 μm, respectively. The results of the sensors characterization show a sensitivity of up to 55 dB re 1 V/Pa when exposed to an acoustic chirp signal ranging from 5-50 kHz at 70-100 dB SPL. This paper presents a test approach necessary for chips with very thin membrane and the results of a dynamic pressure frequency response test.

Link: C4.4 – Characterization of a Piezo-Resistive MEMS Microphone for Aero-Acoustic Measurements · AMA Science (ama-science.org)

Kolja Erbacher; Joao Alves Marques; Malte von Krshiwoblozki; Lixiang Wu; Ha Duong Ngo; Martin Schneider-Ramelow, “Aero Acoustic MEMS Microphone Integration in Ultra-Thin and Flexible Substrate”, 2022 IEEE 24th Electronics Packaging Technology Conference (EPTC), IEEE Xplore: 18 January 2023

Link: Aero Acoustic MEMS Microphone Integration in Ultra-Thin and Flexible Substrate | IEEE Conference Publication | IEEE Xplore

Abstract: The paper describes the integration of novel developed acoustic MEMS sensors, in an ultra-thin and flexible substrate for use in aerospace applications, such as wind tunnel test (WTT) and flight test (FT). The technology allows the fabrication of a large area array with flush mounted microphone sensors without any topography interfering with the flow. The final array contains more than 80 piezoresistive and piezoelectric MEMS sensors, at a dimension of 300×400 mm 2 . The thickness of the bare die array is 600 µm, the array with the packaged sensors below 1550 µm.

José A. García-Souto; Javier Lázaro-Fernández; Pablo Acedo, “Signal conditioning design for aero-acoustic piezoelectric MEMS microphone arrays”, 2022 Symposium on Design, Test, Integration & Packaging of MEMS and MOEMS, IEEE Xplore: 13 October 2022

LINK: Signal conditioning design for aero-acoustic piezoelectric MEMS microphone arrays | IEEE Conference Publication | IEEE Xplore

Abstract: The front-end electronics design for a MEMS microphone array is presented for aero-acoustic applications. It is compliant with the requirements of wind tunnel tests: 100 Hz – 100 kHz bandwidth, 140 dB dynamic range. A multiplexing approach is adopted to reduce the signals distribution of an 80 elements array with two-sections microphones. Considerations for a digital output sensing system are included

Ha Duong Ngo; Kolja Erbacher; Lixiang Wu; Bei Wang; Zirui Pang; Julien Weiss; Pablo Acedo, “A Novel Piezoresitive Microphone MEMS Sensor For Aerospace Applications”, 2022 International Conference on Electrical, Computer and Energy Technologies (ICECET), IEEE Xplore: 09 September 2023

Link: A Novel Piezoresitive Microphone MEMS Sensor For Aerospace Applications | IEEE Conference Publication | IEEE Xplore

Abstract: In this paper we present a microphone sensor for aerospace applications. The novel microphones can be integrated into large arrays for measuring unsteady pressure fluctuations underneath the turbulent boundary layer (TBL), which can be applied to predict the cabin noise excitation. The microphone array has a high spatial resolution due to the small distance between its microphone elements. The microphone sensor is featuring a very thin membrane created by a special technology combining SOI wafer bonding and thinning and TSV (Through Silicon Vias) for contacting from the backside. The membrane thickness is about 4μm. The membrane has a small hole in the middle (diameter about 7μm) drilled by using laser technique. The TSVs are etched in the carrier wafer or interposer by using a KOH or DRIE/BOSCH process.

Lixiang Wu; Tingzhong Xu; Javad Abbaszadeh; Mohssen Moridi, “Piezoelectric MEMS for acoustic and ultrasonic applications”, 2022 IEEE International Symposium on Applications of Ferroelectrics (ISAF), IEEE Xplore: 02 September 2022

Link: Piezoelectric MEMS for acoustic and ultrasonic applications | IEEE Conference Publication | IEEE Xplore

Abstract: Microelectromechanical systems (MEMS) integrated with piezoelectric thin films such as lead zirconate titanate (PZT) and aluminum scandium nitride (AlScN) have played a major role in acoustic and ultrasonic applications. This paper introduces piezoelectric MEMS devices including piezoelectric microphones and piezoelectric micromachined ultrasonic transducers (PMUTs) along with their target applications at various working frequency ranges, such as dual-frequency piezoelectric MEMS microphones for wind tunnel testing, dual-frequency PMUTs for super harmonic imaging, and air-coupled PMUTs with significantly extended bandwidth for gas flow metering.

Lixiang Wu, Xuyuan Chen, Ha Duong Ngo, Emmanuel Julliard and Carsten Spehr, “Design of dual-frequency piezoelectric MEMS microphones for wind tunnel testing” AIAA SCITECH 2022 Forum, AIAA: 29^th December 2021

Link: Design of dual-frequency piezoelectric MEMS microphones for wind tunnel testing | AIAA SciTech Forum

Abstract: The demand for aeroacoustic measurement microphones is surging in recent years as new rules on noise reduction and environmental compliance are getting tougher. However, the state-of-the-art microphones including classical measurement microphones and micro-electro-mechanical systems (MEMS) microphones cannot fully meet the strict requirements for wind tunnel testing (WTT) in terms of form factor, acoustic performance, and product price. To break through the bottleneck, a new type of piezoelectric MEMS microphones with dual frequency bands was designed as key part of a dedicate WTT solution, which aims to capture the unsteady pressure fluctuations underneath the turbulent boundary layer and predict the cabin noise excitation. The finite element method (FEM) was applied to analyze and optimize the MEMS design at the system level. The feasibility of the new MEMS design has been preliminarily verified by characterizing the mechanical and electrical properties of first batch of dual-frequency piezoelectric MEMS microphones. The acoustic characterization was conducted to evaluate the overall performance and the system-level FEM model was refined based on the measurement results.

Kolja J. Erbacher, Ha Duong Ngo, Piotr Mackowiak, Lixiang Wu, Emmanuel Julliard and Carsten Spehr, “Design and modeling of a novel piezoresistive microphone for aero acoustic measurements in laminar boundary layers using FEM and LEM” AIAA SCITECH 2022 Forum, AIAA: 29^th December 2021

Link: Design and modeling of a novel piezoresistive microphone for aero acoustic measurements in laminar boundary layers using FEM and LEM | AIAA SciTech Forum

Abstract: In this paper the modeling and simulation results of a piezo-resistive microphone are presented and a possible fabrication process flow and characterization concept of the sensor are described. The main objective in this funded AEROMIC project is to develop a thin and small in size microphone, which can be integrated into a flexible array, that can be mounted onto an airplane hull for flight tests. The microphone array should be no thicker than 2 mm and should contain more than 80 flush mounted single microphones, allowing acoustic measurement without disturbance of the laminar boundary layer. The pitch of the microphone sensors in the array enable high spatial resolution of the pressure fluctuation. The optimization of geometry of single sensor microphone has been done using FEA (Finite Element Analysis). For the optimization of the geometry of the single microphone chip, FEA of the air damped dynamic behavior of the diaphragm is modeled in Ansys Harmonic Response Analyses with Acoustics ACT package. To model the array on system level, a lumped-element model (LEM) is set up to predict spatial resolution and signal to noise ratio. Derived from the FEA results, a sensor chip layout with three membrane sizes is presented.

Newsletter Entries

2nd Workshop and test campaign at AIRBUS Toulouse (15/12/2023)
SAL visit at USound GmbH facilities for vacuum testing (23/03/2023)
UC3M visit to Silicon Austria Labs GmbH for piezoelectric array testing (25/05/2023)
AEROMIC special session at SMART 2023 conference in Patras, Greece (04/07/2023)
2nd Test campaign at Vectoflow GmbH (24/08/2023)
Final review meeting set on October 24^th 2023: save the date! (31/08/2023)