Modelling of display-compatible piezoelectric micromachined ultrasonic transducers for haptic feedback

In this paper, a physically representative electric equivalent lumped model of a fabricated 600 um diameter polymer-based piezoelectric micromachined ultrasonic transducer (PMUT) is detailed. All parameter values in the lumped model are identified based on electrical impedance measurements in air and in vacuum. The model is then used to predict the emitted ultrasound pressure, the radiated acoustic power and the overall power efficiency. The predictions are validated with experimental data and finite element simulations. Finally, the model is used to estimate the minimum PMUT array size required to reach the expected haptic sensing threshold at a given focus point.