Faculty of Mechanical, Maritime and Materials Engineering, Biomechanical Department, Delft University of Technology, Delft, The Netherlands. Joint first authors.
Bioinspir Biomim. 2017 Dec 4;13(1):016006. doi: 10.1088/1748-3190/aa92b9.
Flexible steerable needles have the potential to allow surgeons to reach deep targets inside the human body with higher accuracy than rigid needles do. Furthermore, by maneuvering around critical anatomical structures, steerable needles could limit the risk of tissue damage. However, the design of a thin needle (e.g. diameter under 2 mm) with a multi-direction steering mechanism is challenging. The goal of this paper is to outline the design and experimental evaluation of a biologically inspired needle with a diameter under 2 mm that advances through straight and curved trajectories in a soft substrate without being pushed, without buckling, and without the need of axial rotation. The needle design, inspired by the ovipositor of parasitoid wasps, consisted of seven nickel titanium wires and had a total diameter of 1.2 mm. The motion of the needle was tested in gelatin phantoms. Forward motion of the needle was evaluated based on the lag between the actual and the desired insertion depth of the needle. Steering was evaluated based on the radius of curvature of a circle fitted to the needle centerline and on the ratio of the needle deflection from the straight path to the insertion depth. The needle moved forward inside the gelatin with a lag of 0.21 (single wire actuation) and 0.34 (double wire actuation) and achieved a maximum curvature of 0.0184 cmand a deflection-to-insertion ratio of 0.0778. The proposed biologically inspired needle design is a relevant step towards the development of thin needles for percutaneous interventions.
柔性可控针有可能使外科医生比刚性针更精确地到达人体内部的深部目标。此外，通过绕过关键的解剖结构，可控针可以限制组织损伤的风险。然而，设计一种直径小于 2 毫米的带有多向转向机构的细针（例如直径小于 2 毫米）具有挑战性。本文的目的是概述一种直径小于 2 毫米的生物启发式针的设计和实验评估，该针在软质基质中能够沿直线和曲线轨迹前进，而无需推动、不会弯曲，并且不需要轴向旋转。该针的设计灵感来自寄生蜂的产卵器，由七根镍钛丝组成，总直径为 1.2 毫米。在明胶模拟物中测试了针的运动。根据针实际和期望插入深度之间的滞后来评估针的前进运动。根据拟合到针中心线的圆的曲率半径和针偏离直线路径的插入深度的比值来评估转向。针在明胶内前进的滞后为 0.21（单丝驱动）和 0.34（双丝驱动），并实现了 0.0184cm 的最大曲率和 0.0778 的偏转与插入深度的比值。所提出的生物启发式针设计是朝着开发用于经皮介入的细针迈出的重要一步。
