Fig. 7: Modes merging in air vs water/tissue.

a LN pMUT 3D membrane displacement measurement and peak detection in air. Modes are matched to COMSOL Multiphysics simulation based on their shape. Here we notice that the peaks are separated from each other due to a high-quality factor in air. The different colors represent different modes extracted from the measurement in air from Fig. 2a. b Simulated combined sound pressure level (SPL) of the device in air. Here we can notice that the different peaks are not merging, instead we have the formation of multiple fractional bands. c Displacement modeling of the resonance peaks under the damping effect of the water and tissue medium. Here the quality factor is getting lower and closer to one another. The different colors represent different modes extracted from the measurement in air from Fig. 2a and then modeled under the damping effect of the water, by decreasing the quality factor. d Modeling of the computed output SPL resulting in a unified large band of BW ≈ 400 kHz, matching very closely with the reference hydrophone measurement.