Development of broadband high-frequency piezoelectric micromachined ultrasonic transducer array

Archive ouverte : Article de revue

Wang, Xu-Bo | He, Le-Ming | Ma, You-Cao | Liu, Wen-Juan | Xu, Wei-Jiang | Ren, Jun-Yan | Riaud, Antoine | Zhou, Jia

Edité par HAL CCSD ; MDPI

International audience. Piezoelectric micromachined ultrasonic transducers (PMUT) are promising elements to fabricate a two-dimensional (2D) array with a pitch small enough (approximately half wavelength) to form and receive arbitrary acoustic beams for medical imaging. However, PMUT arrays have so far failed to combine the wide, high-frequency bandwidth needed to achieve a high axial resolution. In this paper, a polydimethylsiloxane (PDMS) backing structure is introduced into the PMUTs to improve the device bandwidth while keeping a sub-wavelength (λ) pitch. We implement this backing on a 16 × 8 array with 75 µm pitch (3λ/4) with a 15 MHz working frequency. Adding the backing nearly doubles the bandwidth to 92% (−6 dB) and has little influence on the impulse response sensitivity. By widening the transducer bandwidth, this backing may enable using PMUT ultrasonic arrays for high-resolution 3D imaging.

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