Wide-band design of diaphragm pMUT based on induction of strain in thickness direction by aspect ratio control

We have investigated how the bandwidth and sensitivity change by thickening the PZT diaphragm by simulation, and confirmed that those are improved than a general thin diaphragm. In this study, we expect the existence of an appropriate value of the aspect ratio defined between the width and the thickness. We investigate the reception performance of diaphragm transducers consisting of PZT and Si layer by FEM simulation. Design parameter dependence of the ultrasonic reception performance is confirmed by simulation, and its tendency is analyzed. Based on the results, we derive a transducer design method for a desired frequency band. A diaphragm thicker than a certain thickness threshold has a specific bandwidth of 150% or more. The critical thickness is determined by the aspect ratio. A thick diaphragm, that is, a high aspect ratio diaphragm causes coexistence of membrane vibration and thickness vibration. If the thickness is too thick, it becomes a simple vibration of the thickness vibration, and the bandwid...