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This paper deals with the design, simulation and characterization of polymer-based piezoelectric micromachined ultrasound transducers (PMUT) (arrays) intended for short-range gesture recognition applications. The presented process flow is fully compatible with existing flat-panel display fabrication. Finite element models were developed for the evaluation of the frequency response, deflection and acoustic pressure output of single PMUT as a function of the membrane diameter. A laser Doppler vibrometer was used to measure the frequency response, membrane velocity and displacement, as well as mode shapes of the microfabricated PMUT in air. An optical microphone was used to measure the pressure emitted by a single PMUT at various distances along the normal axis of the oscillating membrane. A strong correlation between simulations and measurement results is shown. The device geometries most suitable for shortrange gesture recognition purposes are selected and the radiation pattern of square arrays is analyzed using simulations. The resonance properties of single PMUT in an array are determined using measurements. An optimized array is used to demonstrate pulse-echo measurements, and the requirements for a simple gesture recognition platform are elucidated.

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In this paper, the design, modeling, and characterization of a display compatible pMUT platform are presented. A FEM model is built using COMSOL Multiphysics for evaluating the frequency response, mechanical performance, acoustic pressure, and driving efficiency of our pMUT device across all vibration modes of circular plates. In parallel with it, a first mode analytical model has been developed including electrical, mechanical, and acoustic domains to provide fast estimation for future design. A laser Doppler vibrometer is used to measure the frequency response, displacement, velocity as well as mode shapes of pMUTs with different designs in air. The measured resonance frequency of first mode range from 121.5kHz to 1.1MHz with radius from 500µm to 120µm and fits the prediction of FEM and analytical models. A standard reference microphone is used to measure the acoustic pressure of pMUT inside its frequency range (<125 kHz). The measured acoustic pressure on transverse axis of a 500µm radius pMUT also fits the values from analytical model on acoustic domain.

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