Wang Jiaqi, Zheng Zhou, Chan Jasmine, Yeow John T W
Department of Systems Design Engineering, Faculty of Engineering, University of Waterloo, Waterloo, ON N2L 3G1 Canada.
Microsyst Nanoeng. 2020 Aug 24;6:73. doi: 10.1038/s41378-020-0181-z. eCollection 2020.
Intravascular ultrasound (IVUS) is a burgeoning imaging technology that provides vital information for the diagnosis of coronary arterial diseases. A significant constituent that enables the IVUS system to attain high-resolution images is the ultrasound transducer, which acts as both a transmitter that sends acoustic waves and a detector that receives the returning signals. Being the most mature form of ultrasound transducer available in the market, piezoelectric transducers have dominated the field of biomedical imaging. However, there are some drawbacks associated with using the traditional piezoelectric ultrasound transducers such as difficulties in the fabrication of high-density arrays, which would aid in the acceleration of the imaging speed and alleviate motion artifact. The advent of microelectromechanical system (MEMS) technology has brought about the development of micromachined ultrasound transducers that would help to address this issue. Apart from the advantage of being able to be fabricated into arrays with lesser complications, the image quality of IVUS can be further enhanced with the easy integration of micromachined ultrasound transducers with complementary metal-oxide-semiconductor (CMOS). This would aid in the mitigation of parasitic capacitance, thereby improving the signal-to-noise. Currently, there are two commonly investigated micromachined ultrasound transducers, piezoelectric micromachined ultrasound transducers (PMUTs) and capacitive micromachined ultrasound transducers (CMUTs). Currently, PMUTs face a significant challenge where the fabricated PMUTs do not function as per their design. Thus, CMUTs with different array configurations have been developed for IVUS. In this paper, the different ultrasound transducers, including conventional-piezoelectric transducers, PMUTs and CMUTs, are reviewed, and a summary of the recent progress of CMUTs for IVUS is presented.
血管内超声（IVUS）是一种新兴的成像技术，可为冠状动脉疾病的诊断提供重要信息。使IVUS系统能够获得高分辨率图像的一个重要组成部分是超声换能器，它既作为发送声波的发射器，又作为接收返回信号的探测器。作为市场上最成熟的超声换能器形式，压电换能器在生物医学成像领域占据主导地位。然而，使用传统压电超声换能器存在一些缺点，例如在制造高密度阵列时存在困难，而高密度阵列有助于加快成像速度并减轻运动伪影。微机电系统（MEMS）技术的出现带来了微加工超声换能器的发展，这将有助于解决这个问题。除了能够制造阵列且并发症较少的优点外，微加工超声换能器与互补金属氧化物半导体（CMOS）的轻松集成可以进一步提高IVUS的图像质量。这将有助于减轻寄生电容，从而提高信噪比。目前，有两种常用的微加工超声换能器，即压电微加工超声换能器（PMUT）和电容式微加工超声换能器（CMUT）。目前，PMUT面临一个重大挑战，即制造出的PMUT不能按其设计发挥功能。因此，已为IVUS开发了具有不同阵列配置的CMUT。本文对包括传统压电换能器、PMUT和CMUT在内的不同超声换能器进行了综述，并介绍了CMUT在IVUS方面的最新进展总结。
