Abstract
The purpose of the paper is to design and fabricate a ZnO-based MEMS acoustic sensor for higher sound pressure level (SPL) measurement in the range of 120–200 dB and low frequency infrasonic wave detection. The thickness of silicon diaphragm was optimized for higher SPL using MEMS-CAD-Tool COVENTORWARE. The microtunnel which relates the cavity to the atmosphere was designed and simulated analytically for low cut-off frequency of the sensor in infrasonic band. The resonance frequency of the sensor was obtained using modal analysis. The sensitivity of the sensor was also estimated using COVENTORWARE. The optimized Si-diaphragm thickness for the intended SPL range was determined and found to be 50 μm. The lower cut-off frequency of the sensor for a 10 μm-deep microtunnel was found to be 0.094 Hz. The resonance frequency of the sensor was obtained using modal analysis and found to be 78.9 kHz. Based on simulation results, the MEMS acoustic sensor with 10 μm-deep microtunnel was fabricated. The optimum sensitivity of sensor was calculated using simulated results and found to be 116.4 μVolt/Pa. The lower cut-off frequency of the sensor can be utilized to detect low frequency sounds. The high SPL sensing capability of the device up to 200 dB facilitates detection of high sound pressure level in launch vehicles, rocket motors and weapons’ discharge applications.
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References
Birkett C, Shalis E, Vlahopoulos N, Wu Z (1997) Numerical load generation, vibration analysis, and acoustic signature prediction of a ground vehicle. In: Proceeding of National Conference on Noise Control Engineering, pp 123–128
Blackstock DT (2000) Fundamentals of physical acoustics. Wiley. ch. 4, p 14
Bouwstra S, Storgaard-Larsen T, Scheeper P, Gullov JO, Bay J, Mullenborg M, Rombach P (1998) Silicon microphones-a Danish perspective. J Micromech Microeng 8:64–68
Chang CC, Chang JH (1996) A study on fabrication of zinc oxide thin film acoustic sensors. J Mar Sci Technol 4(1):49–53
Chen PH, Peng HY, Hsieh CM, Chyu MK (2001) The characteristic behavior of TMAH water solution for anisotropic etching on both silicon substrate and SiO2 layer. J Sens Actuators A 93:132–137
Fox RW, McDonald AT, Pritchard PJ (2004) Introduction to fluid mechanics, 6th edn. Wiley, NY
Gill J, Reuben R, Scaife M, Brown E, Steel J (1998) Detection of diesel engine faults using acoustic emission. In: Proceedings of 2nd International Conference on Planned Maintenance, Reliability and Quality, Oxford, England
Giovanni MD (1982) Flat and corrugated membrane design handbook. Marcel Dekker Inc, New York
Hansen ST, Ergun AS, Khuri-Yakub BT (2003) Wideband micromachined acoustic sensors with radiofrequency detection. Proc SPIE 5090:42–50
Kuehne I, Marinkovic D, Eckstein G, Seidel H (2008) A new approach for MEMS power generation based on a piezoelectric diaphragm. J Sens Actuators A 142:292–297
Martin F, Muralt P, Dubois M-A, Pezous A (2004) Thickness dependence of the properties of highly c-axis textured AlN thin films. J Vac Sci Technol 22(2):361–365
Muralt P, Ledermann N, Paborowski J, Barzegar A, Gentil S, Belgacem B, Bosseboeuf A, Setter N (2005) Piezoelectric micromachined ultrasonic transducers based on PZT thin films. IEEE Trans Ultrason Ferroelectr Freq Control 52(12):2276–2288
Peng J, Chao C, Tang H (2010) Piezoelectric micromachined ultrasonic transducer based on dome-shaped piezoelectric single layer. Microsyst Technol 16:1771–1775
Polcawich RG, Scanlon M, Pulskamp J, Clarkson J, Conrad J, Piekarz R, McKinstry ST, Dubey M (2003) Design and fabrication of a lead zirconate titanate (PZT) thin film acoustic sensor. J Integr Ferroelectr 54(1):595–606
Prasad M, Yadav RP, Sahula V, Khanna VK, Shekhar C (2011) Controlled chemical etching of ZnO film for step coverage in MEMS acoustic sensor. J Microelectromech Syst 21(3):517–519
Prasad M, Sahula V, Khanna VK (2013) Design and fabrication of Si diaphragm, ZnO piezoelectric film-based MEMS acoustic sensor using SOI wafers. IEEE Trans Semicond Manuf 26(2):233–241
Scheeper PR, van der Donk AGH, Olthuis W, Bergveld P (1994) A review of silicon microphones. Sens Actuators A 44:1–11
Sezen AS, Sivaramakrishnan S, Hur S, Rajamani R, Robbins W, Nelson BJ (2005) Passive wireless MEMS microphones for biomedical applications. J Biomech Eng 127(6):1030–1034
Wang Z, Wang C, Liu L (2005) Design and analysis of a PZT-based micromachined acoustic sensor with increased sensitivity. IEEE Trans Ultrason Ferroelectr Freq Control 52(10):1840–1850
Wang C, Wang Z, Ren T-L, Zhu Y, Yang Y, Wu X, Wang H, Fang H, Liu L (2007) A micro machined piezoelectric ultrasonic transducer operating in d33 mode using square interdigital electrodes. IEEE Sens J 7(7):967–976
Yamanaka K, Ishikawa S, Nakaso N, Takeda N, Mihara T, Tsukahara Y (2003) Ball SAW devices for hydrogen gas sensor. Proc IEEE Ultrasonic Sympos 1:299–302
Acknowledgements
The author thanks Dr. Chandra Shekhar, the Director and Dr. V.K. Khanna, Head, MEMS and Microsensors Group, CSIR-CEERI, Pilani, for encouragement and guidance.
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Ali, W.R., Prasad, M. Design and fabrication of microtunnel and Si-diaphragm for ZnO based MEMS acoustic sensor for high SPL and low frequency application. Microsyst Technol 21, 1249–1255 (2015). https://doi.org/10.1007/s00542-014-2291-8
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DOI: https://doi.org/10.1007/s00542-014-2291-8