Chen Haoyang, Mirg Shubham, Osman Mohamed, Agrawal Sumit, Cai Jiacheng, Biskowitz Ryan, Minotto Josiah, Kothapalli Sri-Rajasekhar
Department of Biomedical Engineering, The Pennsylvania State University, State College, PA, 16802, USA.
Penn State Cancer Institute, The Pennsylvania State University, Hershey, PA, 17033, USA.
IEEE Sens Lett. 2021 Nov;5(11). doi: 10.1109/lsens.2021.3122097. Epub 2021 Oct 21.
We recently introduced piezoelectric lithium niobate (LN) based transparent ultrasound transducers (TUT) as a new platform for developing multimodal optical, ultrasound and photoacoustic imaging systems. However, LN based TUT is limited in its signal-to-noise ratio due to material's low piezoelectricity ( ). In this paper, we report, for the first time, a 0.2 mm thick transparent lead magnesium niobate-lead titanate (PMN-PT) based TUT (PMN-PT-TUT) for ultrasound and photoacoustic applications and compared its performance with a 0.25 mm thick transparent LN based TUT (LN-TUT). To improve the ultrasound energy transmission efficiency, TUTs were fabricated with a two-matching-layer design. This resulted in a dual frequency response with center frequencies of 7.8 MHz/13.2 MHz and corresponding bandwidths of 28.2%/66.67% for PMN-PT-TUT, and center frequencies of 7.2 MHz/11.8 MHz and bandwidths of 36.1%/62.7% for LN-TUT. The optical transmission rate of PMN-PT-TUTs and LN-TUTs are measured as ~73% and ~91% respectively at 532 nm optical wavelength. The PMN-PT-TUT exhibited higher sensitivity compared to LN-TUT with a nearly three-fold higher pulse echo amplitude and more than two-fold higher photoacoustic amplitude. Furthermore, optical resolution photoacoustic microscopy (ORPAM) experiments on phantom targets demonstrated lateral resolutions of 7 m and 5.1 m, and axial resolutions of 285.6 m and 375.9 m for PMN-PT-TUT and LN-TUT respectively. These results indicated that PMN-PT is a viable alternative to LN for developing TUT based multimodal ultrasound and photoacoustic imaging systems.
我们最近推出了基于压电铌酸锂（LN）的透明超声换能器（TUT），作为开发多模态光学、超声和光声成像系统的新平台。然而，由于材料的压电性较低，基于LN的TUT在信噪比方面存在局限性。在本文中，我们首次报道了一种用于超声和光声应用的0.2毫米厚的基于透明铌镁酸铅-钛酸铅（PMN-PT）的TUT（PMN-PT-TUT），并将其性能与0.25毫米厚的基于透明LN的TUT（LN-TUT）进行了比较。为了提高超声能量传输效率，TUT采用双匹配层设计制造。这导致了PMN-PT-TUT的双频响应，中心频率为7.8 MHz/13.2 MHz，相应带宽为28.2%/66.67%；LN-TUT的中心频率为7.2 MHz/11.8 MHz，带宽为36.1%/62.7%。在532纳米光波长下，PMN-PT-TUT和LN-TUT的光传输率分别测量为73%和91%。与LN-TUT相比，PMN-PT-TUT表现出更高的灵敏度，脉冲回波幅度高出近三倍，光声幅度高出两倍多。此外，对体模目标进行的光学分辨率光声显微镜（ORPAM）实验表明，PMN-PT-TUT和LN-TUT的横向分辨率分别为7微米和5.1微米，轴向分辨率分别为285.6微米和375.9微米。这些结果表明，对于开发基于TUT的多模态超声和光声成像系统，PMN-PT是LN的可行替代品。
