Numerical simulations on the performance of optical-acoustic sensors of minimal dimensions
DOI:
https://doi.org/10.21152/1750-9548.17.1.105Abstract
This paper presents analytical and numerical methods for developing optical-acoustic transducers of minimal dimensions. One can find acoustic sensors used as microphones in various electronic devices such as smartphones or smartwatches. Therefore, it is highly desirable to minimize their size while ensuring high-quality sound reception.
The optical-acoustic sensor relies on laser detection of membrane vibrations and consists of a membrane that vibrates in the presence of an acoustic field and reflects the radiation emitted by the laser back to the laser. We focus on methods to optimize the membrane's design and the cavity (back volume) that separates the laser from the membrane. The back volume compliance significantly affects the sensitivity of the membrane. In addition, it is a noise source due to acoustic and viscous damping. Using calculations and simulations, we show the possibilities of reducing the membrane size and the air-filled back volume size while achieving the desired acoustic properties. We employ analytical calculations for the mechanical vibration of the diaphragm, back-volume compliance and resistance, and precise FEM simulations of the interaction between membrane vibration and the acoustic field. We build on similar techniques used for micromachined capacitive microphones, but we apply these methods newly to a specific setup of backplate-less optical-acoustic sensors. Based on the theoretical results, we can conclude that optical-acoustic devices achieve the same maximum noise level with smaller dimensions than the current industry standard.
References
Stojanovic G, Steele C, Mueller S, Froehlich T, inventors; AMS AG, assignee. Sensors with Corrugated Diaphragms. WO 2020/083791 A1 (WIPO patent) 2020. https://patents.google.com/patent/WO2020083791A1
Seurin J-F, Stojanovic G, Nevou L, inventors; AMS Sensors Asia Pte.Ltd., assignee. Sensing Methods and Sensing Systems. WO 2021/158176 A1 (WIPO patent) 2021. https://patents.google.com/patent/WO2021158176A1
Stojanovic G, Seurin J-F, Xu G, Wang H, Gao P, inventors; AMS International AG, assignee. Optical Acoustic Sensor. WO 2022/084443 A1 (WIPO patent) 2022. https://patents.google.com/patent/WO2022084443A1
Timoshenko S, Woinowsky-Krieger S. Theory of plates and shells. New York: McGraw-hill; 1959 Dec.
Di Giovanni M. Flat and corrugated diaphragm design handbook. Marcel Decker. Inc, New York, page 130ff, 1982. 8, 9. DOI: https://doi.org/10.1201/9780203755969
Scheeper PR, Olthuis W, Bergveld P. The design, fabrication, and testing of corrugated silicon nitride diaphragms. Journal of microelectromechanical systems. 1994 Mar;3(1):36-42. DOI: https://doi.org/10.1109/84.285722
Bitsie, F., Eaton, W.P., Plummer, D.W. and Smith, J.H., 1999. A new analytical solution for diaphragm deflection and its application to a surface-micromachined pressure sensor (No. SAND99-0573C). Sandia National Lab.(SNL-NM), Albuquerque, NM (United States); Sandia National Lab.(SNL-CA), Livermore, CA (United States).
Castellanos‐Gomez A, Singh V, van der Zant HS, Steele GA. Mechanics of freely-suspended ultrathin layered materials. Annalen der Physik. 2015 Jan;527(1-2):27-44. DOI: https://doi.org/10.1002/andp.201400153
Fuldner M, Dehe A, Lerch R. Analytical analysis and finite element simulation of advanced membranes for silicon microphones. IEEE Sensors Journal. 2005 Sep 6;5(5):857-63. DOI: https://doi.org/10.1109/JSEN.2004.841449
Taybi M, Azizollah Ganji B. Modelling of resonance frequency of MEMS corrugated diaphragm for capacitive acoustic sensors. International Journal of Engineering. 2014 Dec 1;27(12):1850-4. DOI: https://doi.org/10.1038/scientificamerican10071854-27d
Azizollah Ganji B, Taybi M. The Effect of Corrugations on Mechanical Sensitivity of Diaphragm for MEMS Capacitive Microphone. International Journal of Engineering, 2013; 26(11): 1323-1330. DOI: https://doi.org/10.5829/idosi.ije.2013.26.11b.07
Hong S, Weihs TP, Bravman JC, Nix WD. Measuring stiffnesses and residual stresses of silicon nitride thin films. Journal of Electronic Materials. 1990 Sep;19(9):903-9. DOI: https://doi.org/10.1007/BF02652915
Jerman JH. The fabrication and use of micromachined corrugated silicon diaphragms. Sensors and Actuators A: Physical. 1990 Apr 1;23(1-3):988-92. DOI: https://doi.org/10.1016/0924-4247(90)87074-S
Schellin R, Hess G, Kühnel W, Thielemann C, Trost D, Wacker J, Steinmann R. Measurements of the mechanical behaviour of micromachined silicon and silicon-nitride membranes for microphones, pressure sensors and gas flow meters. Sensors and Actuators A: Physical. 1994 Apr 1;41(1-3):287-92. DOI: https://doi.org/10.1016/0924-4247(94)80125-8
Schomburg WK. Introduction to microsystem design. Springer; 2015 Jun 25. DOI: https://doi.org/10.1007/978-3-662-47023-7
Gabrielson TB. Fundamental noise limits in miniature acoustic and vibration sensors. NAVAL AIR DEVELOPMENT CENTER WARMINSTERPA MISSION AVIONICS TECHNOLOGY DEPT; 1991 Dec 31. DOI: https://doi.org/10.1115/1.2874471
Gabrielson TB. Mechanical-thermal noise in micromachined acoustic and vibration sensors. IEEE transactions on Electron Devices. 1993 May;40(5):903-9. DOI: https://doi.org/10.1109/16.210197
Stemme G. Resonant silicon sensors. Journal of Micromechanics and Microengineering. 1991 Jun 1;1(2):113. DOI: https://doi.org/10.1088/0960-1317/1/2/004
Kuntzman ML, LoPresti JL, Du Y, Conklin WF, Naderyan V, Lee SB, Schafer D, Pedersen M, Loeppert PV. Thermal boundary layer limitations on the performance of micromachined microphones. The Journal of the Acoustical Society of America. 2018 Nov 19;144(5):2838-46. DOI: https://doi.org/10.1121/1.5070155
Naderyan V, Raspet R, Hickey C. Analytical, computational, and experimental study of thermoviscous acoustic damping in perforated micro-electro-mechanical systems with flexible diaphragm. The Journal of the Acoustical Society of America. 2021 Oct 14;150(4):2749-56. DOI: https://doi.org/10.1121/10.0006378
Škvor Z. On the acoustical resistance due to viscous losses in the air gap of electrostatic transducers. Acta acustica united with acustica. 1967 Jan 1;19(5):295-9.
Tarnow V. The lower limit of detectable sound pressures. The Journal of the Acoustical Society of America. 1987 Jul;82(1):379-81. DOI: https://doi.org/10.1121/1.395526
Çaldichoury I, Souli M, Sarradj E, Geyer T, Pin F. Numerical investigation of flow around hairy flaps cylinder using FSI Capabilities. The International Journal of Multiphysics. 2018 Jun 30;12(2):189-208. DOI: https://doi.org/10.21152/1750-9548.12.2.189.
Tabiei A, Chowdhury M, Aquelet N, Souli M. Transient response of a projectile in gun launch simulation using Lagrangian and ALE methods. The International Journal of Multiphysics. 2010 Jun 30;4(2):151-73. DOI: https://doi.org/10.1260/1750-9548.4.2.151
Sigrist J. An overview of engineering numerical methods for the dynamic analysis of a nuclear reactor with fluid-structure interaction modelling. The International Journal of Multiphysics. 2009 Mar 31;3(1):31-60. DOI: https://doi.org/10.1260/175095409787924490
COMSOL Multiphysics® v. 5.6. COMSOL AB, Stockholm, Sweden. https://www.comsol.com/
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