Broadband gradient impedance matching using an acoustic metamaterial for ultrasonic transducers

作者：Zheng Li, Dan-Qing Yang, Shi-Lei Liu, Siyuan Yu, Ming‐Hui Lu, Jie Zhu, Shan-Tao Zhang, Ming-Wei Zhu, Xia-Sheng Guo, Hao-Dong Wu, Xinlong Wang, Yan‐Feng Chen · 发表于：Scientific Reports · 年份：2017 · DOI：10.1038/srep42863 · 被引用次数：105 · 研究领域：Acoustic Wave Phenomena Research、Ultrasonics and Acoustic Wave Propagation、Ultrasound Imaging and Elastography

High-quality broadband ultrasound transducers yield superior imaging performance in biomedical ultrasonography. However, proper design to perfectly bridge the energy between the active piezoelectric material and the target medium over the operating spectrum is still lacking. Here, we demonstrate a new anisotropic cone-structured acoustic metamaterial matching layer that acts as an inhomogeneous material with gradient acoustic impedance along the ultrasound propagation direction. When sandwiched between the piezoelectric material unit and the target medium, the acoustic metamaterial matching layer provides a broadband window to support extraordinary transmission of ultrasound over a wide frequency range. We fabricated the matching layer by etching the peeled silica optical fibre bundles with hydrofluoric acid solution. The experimental measurement of an ultrasound transducer equipped with this acoustic metamaterial matching layer shows that the corresponding -6 dB bandwidth is able to reach over 100%. This new material fully enables new high-end piezoelectric materials in the construction of high-performance ultrasound transducers and probes, leading to considerably improved resolutions in biomedical ultrasonography and compact harmonic imaging systems.