Piezoelectric Micro Ultrasonic Transducer (PMUT) For Underwater Sonar Applications

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dc.contributor.authorYaacob, Mohd Ikhwan Hadi
dc.date.accessioned2017-11-02T02:41:43Z
dc.date.available2017-11-02T02:41:43Z
dc.date.issued2013-07
dc.description.abstractTypical piezoelectric micro ultrasonic transducer (pMUT) yields resonance in the very high frequency (VHF) range, due to its thin membrane structure. Thin piezoelectric film utilized in pMUT has reduced its receiving sensitivity and require thick encapsulation layer to avoid damage to the membrane. Development of pMUT specifically for underwater usage was described in this thesis. Main objective for this study is to tune the pMUT resonance into the medium frequency (MF) range while improving the sensitivities. This was achieved by simulating the pMUT with water loading, utilizing CuAl10Fe4 also known as “sea bronze” alloy film as part of the vibrating membrane and simplifying the fabrication process through polymer adhesive wafer bonding method. Design process started with benchmarking six existing pMUT’s architectures from various researchers. From that, total of ten pMUT designs were proposed and analyzed using finite element modeling (FEM), with different shapes, dimensions and materials. FEM and device’s simulation was carried out using CoventorWare software. From the simulation, pMUT design using lead-zirconatetitanate (PZT) with “sea bronze” film coating on Polydimethyl-Siloxane (PDMS) membrane at 2 mm diameter and 142.3 μm of thickness was found to carry resonance between 85.9 - 101.0 kHz. This design was then fabricated. Total of four prototypes have been fabricated using PZT-5A and PZT-5H ceramics with and without “sea bronze” alloy coating. Key fabrication methods include the sputtering of “sea bronze” alloy and SiO2 as well as the spin-coating of PDMS. At the sputtering yield of 5.9732 W/cm2, deposition rate for sea bronze alloy was discovered at 16.667 nm per minute. Extensive energy dispersive x-ray (EDX) and atomic force microscopy (AFM) analyses were carried out on the deposited alloy to determine its composition change and the surface roughness respectively. Finally, pMUT chips was adhered on the printed circuit board (PCB) and sealed using epoxy. An equivalent circuit for each pMUT including all circuit parameters was determined according to the BVD approximation and curve fittings via impedance analysis. Throughout the fabrication phase, material layer thickness was measured using cross sectional SEM. In the final stage of device’s implementation, all fabricated pMUTs have undergone underwater calibration and characterization. Underwater calibration data revealed that the pMUT with CuAl10Fe4 coating on PZT ceramics have shown 50-100 kHz decrement in resonant frequency compared to the original PZT, with positive gain in sensitivity between 0.65-5.09 dB.en_US
dc.identifier.urihttp://hdl.handle.net/123456789/5220
dc.language.isoenen_US
dc.publisherUniversiti Sains Malaysiaen_US
dc.subjectPiezoelectric micro ultrasonic transduceren_US
dc.subjectfor underwater sonar applicationsen_US
dc.titlePiezoelectric Micro Ultrasonic Transducer (PMUT) For Underwater Sonar Applicationsen_US
dc.typeThesisen_US
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