Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education, Tianjin University, Tianjin, 300072, China.
Int J Comput Assist Radiol Surg. 2018 May;13(5):671-682. doi: 10.1007/s11548-018-1722-x. Epub 2018 Mar 8.
BACKGROUND/PURPOSE: Robotic-assisted endovascular intervention surgery has attracted significant attention and interest in recent years. However, limited designs have focused on the variable stiffness mechanism of the catheter shaft. Flexible catheter needs to be partially switched to a rigid state that can hold its shape against external force to achieve a stable and effective insertion procedure. Furthermore, driving catheter in a similar way with manual procedures has the potential to make full use of the extensive experience from conventional catheter navigation. Besides driving method, force sensing is another significant factor for endovascular intervention.
This paper presents a variable stiffness catheterization system that can provide stable and accurate endovascular intervention procedure with a linear stepping mechanism that has a similar operation mode to the conventional catheter navigation. A specially designed shape-memory polymer tube with water cooling structure is used to achieve variable stiffness of the catheter. Hence, four FBG sensors are attached to the catheter tip in order to monitor the tip contact force situation with temperature compensation.
Experimental results show that the actuation unit is able to deliver linear and rotational motions. We have shown the feasibility of FBG force sensing to reduce the effect of temperature and detect the tip contact force. The designed catheter can change its stiffness partially, and the stiffness of the catheter can be remarkably increased in rigid state. Hence, in the rigid state, the catheter can hold its shape against a [Formula: see text] load. The prototype has also been validated with a vascular phantom, demonstrating the potential clinical value of the system.
The proposed system provides important insights into the design of compact robotic-assisted catheter incorporating effective variable stiffness mechanism and real-time force sensing for intraoperative endovascular intervention.
背景/目的：近年来，机器人辅助血管内介入手术受到了广泛关注和兴趣。然而，有限的设计集中在导管轴的可变刚度机制上。柔性导管需要部分切换到刚性状态，以保持其形状抵抗外力，从而实现稳定有效的插入过程。此外，以类似于手动操作的方式驱动导管有可能充分利用传统导管导航的广泛经验。除了驱动方法外，力感测也是血管内介入的另一个重要因素。
本文提出了一种可变刚度导管系统，该系统可以通过类似于传统导管导航的操作模式的线性步进机构提供稳定准确的血管内介入手术。使用专门设计的具有水冷结构的形状记忆聚合物管来实现导管的可变刚度。因此，在导管尖端附有四个 FBG 传感器，以监测尖端接触力情况并进行温度补偿。
实验结果表明，驱动单元能够实现线性和旋转运动。我们已经展示了 FBG 力感测的可行性，以减少温度的影响并检测尖端接触力。设计的导管可以部分改变其刚度，并且在刚性状态下导管的刚度可以显著增加。因此，在刚性状态下，导管可以抵抗[公式：见文本]负载保持其形状。该原型还在血管模型上进行了验证，展示了该系统的潜在临床价值。
所提出的系统为设计紧凑的机器人辅助导管提供了重要的见解，该导管结合了有效的可变刚度机构和实时力感测，用于术中血管内介入。
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