Mechanical Engineering Department, National Taiwan University, Taipei 10617, Taiwan.
Sensors (Basel). 2019 Oct 23;19(21):4616. doi: 10.3390/s19214616.
Recently, smart stents have been developed by integrating various sensors with intravascular stents for detecting vascular restenosis or monitoring intravascular biomedical conditions such as blood pressure or blood flow velocity. The information on biomedical signals is then transmitted to external monitoring systems via wireless communications. Due to the limited volumes of blood vessels and limited influence of blood flow, antennas with good radiation performance are required for intravascular applications. In this paper, we propose a stent antenna composed of multiple rings containing crowns and struts, where each ring is connected with one connector. Unlike a conventional stent, wherein each ring is connected with several connectors, the single connector prevents the random distribution of electrical current and thus achieves good radiation performance. The implantable stent antenna is designed for the frequency range of 2 to 3 GHz for minimum penetration loss in the human body and tissues. Mechanical FEM simulations were conducted to ensure that the mechanical deformation was within specific limits during balloon expansions. A prototype was fabricated with laser cutting techniques and its radiation performance experimentally characterized. It was demonstrated that the fabricated stent antenna had an omnidirectional radiation pattern for arbitrary receiving angles, a gain of 1.38 dBi, and a radiation efficiency of 74.5% at a resonant frequency of 2.07 GHz. The main contribution of this work was the manipulation of the current distributions of the stent for good EM radiation performances which needed to be further examined while inserted inside human bodies. These research results should contribute to the further development of implantable wireless communications and intravascular monitoring of biomedical signals such as blood pressure and blood flow velocity.
最近，通过将各种传感器与血管内支架集成，开发出了智能支架，用于检测血管再狭窄或监测血压或血流速度等血管内生物医学状况。然后，通过无线通信将生物医学信号信息传输到外部监测系统。由于血管的体积有限，血流的影响有限，因此需要具有良好辐射性能的天线用于血管内应用。在本文中，我们提出了一种由多个包含冠和支柱的环组成的支架天线，其中每个环都与一个连接器相连。与传统的支架不同，传统支架的每个环都与几个连接器相连，而单个连接器可以防止电流的随机分布，从而实现良好的辐射性能。植入式支架天线的设计频率范围为 2 至 3 GHz，以在人体和组织中实现最小的穿透损耗。进行了机械有限元模拟，以确保在球囊膨胀过程中机械变形在特定限制内。使用激光切割技术制造了原型，并对其辐射性能进行了实验表征。结果表明，所制造的支架天线在任意接收角度下具有全向辐射模式，在 2.07GHz 的谐振频率下，增益为 1.38dBi，辐射效率为 74.5%。这项工作的主要贡献是操纵支架的电流分布以实现良好的电磁辐射性能，这需要在插入人体内部时进一步研究。这些研究结果应该有助于进一步开发植入式无线通信和生物医学信号（如血压和血流速度）的血管内监测。
