Now showing 1 - 3 of 3
  • Publication
    Simulation and investigation of Si-based piezoelectric micromachined ultrasonic transducer (PMUT) performances
    Micro-electromechanical system (MEMS) based piezoelectric ultrasonic transducers for acoustic imaging of the surroundings are known as piezoelectric micromachined ultrasonic transducers (PMUTs). This research proposes a structural design of the PMUT with four fixed-guided beams. The beam is subjected to lateral loads, with vectors that are perpendicular to the longitudinal axis. This project simulated Piezoelectric Micromachined Ultrasonic Transducer (PMUT) with three different material properties i.e. Aluminium Nitride (AlN), Lead zirconate titanate (PZT) and Zinc Oxide (ZnO). Based on the study, it was found that reducing the beam dimensions and increasing the plate size will result in the first mode frequency reduction from 1.33x107 Hz to 3.74x106 Hz. Other than that, it was found that AlN PMUT experienced the maximum deflection of 6.3413 to 6.3478 μm when the loads applied in the range of 50 to 200 μN/m2. When the piezoelectric material changed to PZT, we obtained the maximum deflections of 0.3771 to 0.3786 μm when the same loads range applied to the PMUT. As for the ZnO PMUT, the maximum deflections obtained were in between 0.1702 μm to 0.1772 μm with the loads are maintained as in the loads applied to the AlN and PZT. This study proved the significant impact of altering the structural dimensions and material properties of PMUTs on their operational characteristics, specifically the first mode frequency and deflection behavior.
  • Publication
    Design and simulation of micro-electro-mechanical systems (MEMS) capacitive pressure sensor for thermal runaway detection in the electric vehicle
    Recent advancement of vehicle technologies has resulted in development of replacing conventional Internal combustion engine (ICE) to Electric Vehicle (EV) mostly powered by Lithium-ion batteries (LIB). These batteries contain massive amount of energy confined in a very small space. Thermal runaway occurs when the batteries and its circuits start to heat up anomaly. Thermal runaway can cause failures that can lead to battery ignition, resulting in explosions and imminent threats to life and property. This research focused on MEMS capacitance pressure sensor, using three distinct square slotted diaphragm designs: clamped-square, four-slotted-square, and eight-slotted-square diaphragms. The investigation commenced with an evaluation of diaphragm performance, and subsequently, the diaphragm was integrated into the structure of the MEMS capacitive pressure sensor and subjected to simulation. Varied pressure levels ranging from 0.1 to 0.35 MPa were applied to both the diaphragm and the pressure sensor. The outcomes revealed that the eight-slotted-square diaphragm yielded the most substantial displacement, registering at 5.507 μm. It also exhibited the highest Mises stress of 644.67 MPa, and recorded the highest mechanical sensitivity at 15.7545 (10-12/Pa). The clamped-square design, despite its slotted area, yielded the highest capacitance value among the three designs for the pressure sensor.
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  • Publication
    Digital fringe projection system for round shaped breast tumor detection
    ( 2020-01-01) ; ; ;
    Vithyacharan Retnasamy
    ;
    Rajendaran Vairavan
    ;
    The digital fringe projection has been widely used in the field of surface imaging however its application in the field of body imaging especially for human breasts is still quite limited. Currently, the common imaging modality for breast tumor diagnoses are breast ultrasound and mammogram. There are advantages and limitations of using the mammogram and ultrasound in terms of the procedure of the process and the non-invasive nature of the procedure. In this work, an automated digital fringe projection system is developed to execute the imaging of surface changes of a helical shaped phantom breast. The fringe projection setup utilizes a computer, LCD projector, and a CCD camera. The tumor used was round-shaped with a diameter size of 1.5 and 2 cm. The fringe pattern was projected through the three-step phase shift where a resulting phase map was obtained. Results demonstrated that the system was able to identify an average pixel shift of five and ten on the breast surface caused by the presence of the round breast tumors.
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