A 15-MHz 1-3 Piezocomposite Concave Array Transducer for Ophthalmic Imaging
A 15-MHz 1-3 Piezocomposite Concave Array Transducer for Ophthalmic Imaging
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DOI：
10.1109/tuffc.2015.007288
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发表时间：
2015-11-01
影响因子：
3.6
通讯作者：
Chang, Jin Ho
中科院分区：
文献类型：
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作者：
Cha, Jung Hyui;Kang, Byungwoo;Chang, Jin Ho
由于人眼的球面形状，眼睛的前段，特别是角膜和晶状体，产生了高水平的折射和超声反射，这对线性和凸形阵列的性能产生了负面影响。为了最大限度地减少超声能量损失，设计、制造和表征了一种15 MHz凹面阵列换能器，其占地面积能够与角膜的形状很好地匹配。凹面阵列具有半径为15 mm的曲率和128个具有1.44 nm节距的单元。它的高度焦点和视角分别为30毫米和72.3度，从而允许成像区域覆盖后段的视网膜感兴趣区域。针对凹面阵的双向(方位和垂直)曲率和高耦合系数，设计并制作了1-3型压电复合材料作为有源层。通过性能评估发现，经过电调后，完成的凹面阵的中心频率为15.95 MHz，-6db的分数带宽为67.8%。测试结果表明，串扰电平小于-25分贝。通过使用定制的仿眼模型进行脉冲回波测试，验证了凹面阵列对角膜的折射和反射具有较强的鲁棒性。此外，线目标体模和体外猪眼的图像都通过完成的凹形阵列获得，该凹形阵列连接到配备研究包的商用超声扫描仪。评价结果表明，研制的凹面阵列换能器可能是一种替代传统阵列的有效成像眼睛后段的方法。
Because of the spherical shape of the human eye, the anterior segments of the eye, particularly the cornea and the lens, create high levels of refraction and reflection of ultrasound which negatively affect the performance of linear and convex arrays. To minimize the ultrasound energy loss, a 15-MHz concave array transducer was designed, fabricated, and characterized; its footprint is able to mesh well with the shape of the cornea. The concave array has a curvature with a radius of 15 mm and 128 elements with a 1.44 lambda pitch. Its elevational focus and view angle are 30 mm and 72.3 degrees, respectively, thus allowing the imaging area to cover the retinal region of interest in the posterior segment. As an active layer, a 1-3 piezocomposite was designed and fabricated in response to the bidirectional (i.e., azimuthal and elevational) curvature of the concave array and the high coupling coefficient. From the performance evaluation, it was found that the completed concave array is able to provide a center frequency of 15.95 MHz and a -6-dB fractional bandwidth of 67.8% after electrical tuning has been conducted. The crosstalk level was measured to be less than -25 dB. It was verified that the concave array is robust to the refraction and reflection from the cornea through pulse-echo testing using a custom-made eye-mimicking phantom. Furthermore, images of both the wire-target phantom and the ex vivo porcine eye were acquired by the finished concave array, which was connected to a commercial ultrasound scanner equipped with a research package. The evaluation results demonstrated that the developed concave array transducer is a possible alternative to conventional arrays for effectively imaging the posterior segment of the eye.