Aluminum Nitride 4-Beam Piezoelectric Nanoscale Ultrasound Transducer (pNUT)

In this work, we study thickness down-scaling as a technique to miniaturize piezoelectric ultrasound transducers while preserving a frequency of operation that falls in the 40-100 kHz range, where airborne ultrasound can propagate over several meters distances and attenuation is <3 dB/m. We propose a novel transducer design, the 4-beam piezoelectric nanoscale ultrasound transducer (pNUT), to mitigate the effect of residual stress associated with thickness scaling. We use an equivalent circuit model to describe the device dynamics, along with non-idealities that need to be accounted for during the design phase. The model is validated by experimental data, showing that the pNUTs can achieve open-circuit receive (Rx) sensitivities of up to 1 mV/Pa while occupying a total area of approximately 100 mu m x 100 mu m. We compare this performance to the sensitivities of ultrasound sensors recently published in literature, showing an increase in Rx sensitivity per unit area between 1 and 2 orders of magnitude.

Automated summary

In this study, a novel piezoelectric nanoscale ultrasound transducer (pNUT) design was proposed to achieve high sensitivity while mitigating residual stress effects associated with thickness scaling. An equivalent circuit model and experimental data validation were used to demonstrate the high sensitivity of the design in a small area. Compared to other ultrasound sensors in the literature, the pNUT design showed significantly improved sensitivity performance per unit area.