Finite element method analysis of acoustic beam width and intensity of square PMUT arrays under different array configurations

Abstract

This study investigates the acoustic beam width and intensity of ultrasonic beams produced by a Piezoelectric Micromachined Ultrasonic Transducer (PMUT) array, specifically examining how removing certain array elements can improve beam focusing. A narrower, more focused beam can enhance acoustic energy concentration in the target region while improving spatial resolution to distinguish smaller features. For this analysis, the finite element method in the COMSOL Multiphysics application is used to simulate the micrometer-scale structures and features of the PMUT arrays. The beam width, a measure of beam focusing, is quantified by the full width at half maximum (FWHM). The results show that removing some central elements slightly reduces the FWHM, indicating improved focusing of the acoustic beam, whereas removing only the central element does not significantly affect the beam width. The results also show that removing some array elements decreases the acoustic intensity; however, this reduction can be compensated for by increasing the voltage by 1 V or higher while maintaining a tighter beam width. Selectively removing elements can effectively enhance beam focusing while preserving acoustic intensity with slightly higher potential difference. This approach may be useful for applications that require improved spatial resolution and more concentrated acoustic energy.