IEEE Trans Ultrason Ferroelectr Freq Control. 2017 Feb;64(2):391-401. doi: 10.1109/TUFFC.2016.2620381. Epub 2016 Oct 24.
Multifrequency capacitive micromachined ultrasound transducers (CMUTs) are introduced consisting of interlaced 82- [Formula: see text] (low frequency) and 36- [Formula: see text] (high frequency) membranes. The membranes have been interlaced on a scale smaller than the shortest wavelength of operation allowing several advantages over other multifrequency transducer designs including aligned beam profiles, optimal imaging resolution, and minimal grating lobes. The low- and high-frequency CMUTs operate at 1.74 and 5.04 MHz in immersion, respectively. Multifrequency transducers have applications in wideband photoacoustic (PA) imaging where multifrequency transducers are better able to detect both high- and low-frequency PA frequency content. The PA frequency content is target size dependent, which means traditional high-frequency transducers have less sensitivity to larger objects such as diffuse contrast agents. We demonstrate that the low-frequency subarrays are able to better visualize diffuse agent distributions, while the high-frequency subarrays offer fine-resolution imaging important for microvascular imaging and structural navigation. Spectroscopically unmixed images superimpose high sensitivity images of agent concentrations (acquired using low-frequency subarrays) onto high-resolution images of microvessel-mimicking phantoms (acquired using high-frequency subarrays).
交错式 82- [公式：见正文]（低频）和 36- [公式：见正文]（高频）膜的多频电容式微机械超声换能器（CMUT）被引入。这些膜交错排列的尺度小于工作的最短波长，与其他多频换能器设计相比具有多个优势，包括对准的波束轮廓、最佳成像分辨率和最小的栅瓣。低频和高频 CMUT 在浸没中分别工作在 1.74MHz 和 5.04MHz。多频换能器在宽带光声（PA）成像中有应用，多频换能器能够更好地检测高频和低频 PA 频率内容。PA 的频率内容与目标大小有关，这意味着传统的高频换能器对大物体（如弥散对比剂）的灵敏度较低。我们证明低频子阵能够更好地可视化弥散剂分布，而高频子阵则提供了用于微血管成像和结构导航的精细分辨率成像。通过光谱解混，可以将（使用低频子阵获取的）药物浓度的高灵敏度图像叠加到（使用高频子阵获取的）微血管模拟体模的高分辨率图像上。
