Low-Crosstalk PMUT Array Based on Lithium Niobate Single-Crystal Thin Film for High-Resolution Imaging

As modern ultrasound devices move towards miniaturization, wearable, and portability, traditional ultrasonic transducers used for imaging encounter limitations that impede achieving satisfactory performance. Utilizing miniaturized, integrated, mass-produced, and low-power micromachined piezoelectric ultrasound transducers (PMUTs) to fabricate miniature ultrasound devices are considered a viable solution. However, PMUTs have been constrained by bandwidth and are susceptible to crosstalk, resulting in challenges such as reduced imaging resolution and artifact occurrence, which notably affect the quality of image. To tackle the aforementioned challenges, this study utilizes biocompatible lithium niobate (LiNbO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub>, LN) single crystal thin films to fabricate a 16-channel PMUT array. By incorporating the annular channel separation structure (CSS) around each channel, the crosstalk between channels has been minimized to the greatest extent. In water, the LN PMUT imaging array operates at a frequency of 2.06 MHz with a -3 dB bandwidth of up to 0.8 MHz (39.1%). Imaging characterization demonstrates that the fabricated LN PMUT achieves a measured resolution of 0.45 mm, in excellent agreement with theoretical predictions. LN PMUT has demonstrated significant advantages and potential in the emerging field of ultrasound.