Research on low-crosstalk PMUT with helmholtz cavity-based sonic crystal using FEM simulation

Abstract The crosstalk effect in piezoelectric micromachined ultrasound transducer (PMUT) arrays is a significant challenge that negatively impacts device performance. To address this issue, this study utilizes the excellent sound isolation properties of sonic crystals by designing a multi-resonant cavity sonic crystal structure, which is integrated into the PMUT chip. The designed PMUT features a resonant cavity with a radius of 200 μm and a resonant frequency of 785 kHz. Furthermore, this new structure has been validated through finite element simulations and has been compared with traditional PMUT and isolation pillar PMUT. The results show that, compared to traditional PMUTs, the single-period and two-period sonic crystal PMUTs achieve a significant reduction in crosstalk—by 45.9% and 55.2%, respectively—reaching crosstalk coefficients as low as 0.50% and 0.30%. And the proposed sonic crystal strategy outperforms the existing isolation pillar approach. Additionally, the study investigates the crosstalk formation mechanism in PMUTs with convex isolation structures, highlighting sound diffraction as a key factor contributing to this phenomenon.