3-D printing of architected hydrophones

Piezoelectric hydrophones play a key role in underwater applications such as communication and seafloor mapping. Conventional ceramic manufacturing techniques constrain hydrophone designs to simple geometries, limiting their sensitivity, directivity, and frequency bandwidth. This work presents a novel class of high-performance 3-D-printed piezoelectric hydrophones with rationally designed micro-architectures. By employing a high-resolutionlight-based printing technique combined with optimized liquid-phase sintering, the piezoelectric coefficients and electromechanical coupling factor achieve 92% and 85%, respectively, of the values seen in pristine materials. A systematic framework was developed to tune piezoelectric properties by adjusting the spatial arrangement and thickness of unit cell struts, resulting in hydrophones with 15 dB higher sensitivity compared to commercial counterparts and customizable directivity patterns. This allows for Direction of Arrival (DoA) estimation without the need for hydrophone arrays and achieves a hydrostatic figure of merit up to five times higher than that of commercial hydrophones. Initial machine learning studies for sub-hydrostatic frequency DoA estimation also show promising results, specifically when it comes to the resilience of the device to noise or acoustic crosstalk—the latter even becomes an advantage for our device whereas it is rather a source of confusion for traditional transducers arrays.