Non-linear Behavior of pMUT for High Sound Pressure Generation

抄録

High sound pressure is always preferred in pMUT (piezoelectric micromachined ultrasonic transducer) applications, and large displacement becomes the key to achieving high SPL (sound pressure level). However, large displacement also leads to non-linearity, which will bring significant deviations from the design goals and is usually difficult to predict in simulation by finite element method. To investigate the non-linear characteristics, non-linear fitting was used to quantitatively analyze two different structures in this study. The frequency response and quality factor change experimentally observed in non-linear region were discussed. In addition, a structure with a central mass attached to promote piston-like vibration was investigated. Compared to the conventional structure, the proposed structure had a 30% smaller non-linear coefficient and an 81.3% larger non-linear damping. However, higher SPL was not obtained due to the lower natural frequency and amplitude of displacement.