Modeling and Optimization of MEMS-Based Acoustic Sensor for Underwater Applications SHEVTSOV, S. 1 , PARINOV, I. 2 , ZHILYAEV, I. 1 , CHANG, S.-H. 3 , LEE J. C.-Y. 3 , WU, P.-C. 4 , LIN C.-F. 5 , WUU, D.-S. 6 1 Mechanical Engineering Lab, 2 Physics of Strength Dept., 3 Microelectronics Engineering Dept., 4 Nanoscience and Nanotechnology Center, 5 Research Development Dept. 1 South Center of Russian Academy, 2 Southern Federal University, 3 National Kaohsiung Marine University, 4 National Chung Hsing University, 5 National Taiwan Ocean University, 6 Dayeh University 1 No. 41, Tchekhov str., 344006, 2 No.201, Stachki str., 344094, Rostov-on-Don 3 No.142, Haijhuan Rd., Nanzih Dist., Kaohsiung City 81157, 4 No.250 Kuo Kuang Rd., Taichung 402, 5 No. 2 Pei-Ning Road, Keelung 20224, 6 No.168, University Rd., Dacun, Changhua 51591 1,2 RUSSIA, 3-6 TAIWAN (R.O.C.) aeroengdstu@list.ru http://www.ssc–ras.ru Abstract: - This paper presents some results of finite element (FE) analysis performed for membrane-type piezoceramic transducer for underwater acoustics applications at water deep up to 200 meters. We investigate the miniaturized membrane-type sensor with perforated holes in the active PZT membrane, intermediate, and protective plates. In this investigation an influence of the polyimide plate viscous damping, the membranes dimensions and the relative area of the perforated holes on the sensitivity frequency response of the MEMS devices was studied for the broadening the operating frequency band. A possibility of optimize these key parameter using the genetic algorithm working with the device’s FE model was demonstrated. Key-Words: - Underwater Acoustics, Hydrophone, MEMS devices, Piezoelectric, Finite Element Analysis 1 Introduction The design of high-sensitive hydrophones is one of the research interests in underwater acoustics. A detailed description of the design concepts of piezoelectric sensors and equivalent circuit parameters were provided in many monographs and overviews (see, e.g. [1−2]). Last two decades a number of the structural concepts for high-sensitive underwater transducers have been proposed. Due to progress of micro- and nanotechnology the most attention of researchers is attracted the transducers that use the micro-electromechanical system (MEMS) concept. Piezoelectric micro-machined ultrasonic transducers (pMUTs) present a new approach to sound detection and generation that can overcome the shortcomings of conventional transducers. In pMUTs, the sound-sensoring element is a micromachined multi-layered membrane with a piezoactive layer, typically a thin lead-zirconate-titanate (PZT) film [4−7]. Such film can be formed by a batch-mode fabrication technology for integration of bulk piezoelectric materials into MEMS devices [8, 9]. Typical fabrication techniques include a low-temperature bonding technique using a spin-on polymer (Cytop), design of electrode interconnect, chemical mechanical polishing (CMP) for thinning down the bulk PZT, and Deep-Reactive-Ion-Etching (DRIE) of silicon [8, 9]. An example of such typical hydrophone structure is shown on the Fig. 1. For practical reasons, hydrophones with wider bandwidth are desired, and the main requirement to the hydrophone structure is the uniformity of the frequency response function (FRF) for sensitivity in the specified frequency range. Because of it, one need to optimize the main structural parameters of the hydrophone, and to state corresponding geometrical characteristics such as: device length and width, the thickness of each material layer, the depth of wells in silicon substrate, the bore diameter of five layers of materials, and relative surface area of the perforated holes. The first part of the paper is devoted to the hydrophone’s FE model construction. In order to reduce a number of degree of freedom for the hydrophone’s FE model we determined the effective modules of PZT and SiO 2 membranes with holes. In the final part the genetic algorithm for the FRF of hydrophone’s sensitivity optimization is proposed and discussed. Recent Researches in Applied Mechanics ISBN: 978-1-61804-078-7 88