Fig. 2: Acoustic performance of PMUT arrays with varying spacing but fixed array area (2.2 mm × 2.2 mm).

a Simulated acoustic fields at the resonance frequency for arrays with cell spacing of 50 µm, 100 µm, and 150 µm respectively. b Ultrasound pressure responses versus frequencies at 1 cm depth for arrays with cell spacing varying from 40 µm to 150 µm. c Theoretical and experimental normalized ultrasound sensitivity, and (d) the normalized −6 dB bandwidth as a function of cell spacing at 1 cm depth of the array