Department of Biomechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Delft, The Netherlands.
PLoS One. 2019 Sep 4;14(9):e0221165. doi: 10.1371/journal.pone.0221165. eCollection 2019.
Needles with diameter under 1 mm are used in various medical applications to limit the risk of complication and patient discomfort during the procedure. Next to a small diameter, needle steerability is an important property for reaching targets located deep inside the body accurately and precisely. In this paper, we present a 0.5-mm prototype probe which is able to steer in three dimensions (3D) without the need of axial rotation. The prototype consists of three Nitinol wires (each with a diameter of 0.125 mm) with a pre-curved tip. The wires are kept together by a stainless steel tube. Each wire is clamped to a block which translates along a leadscrew, the rotation of the latter being controlled by a wheel connected at the distal end of the leadscrew. The tip bends upon retraction of one or two wires. When pushed through a soft solid structure (e.g., a soft tissue or soft tissue phantom), the probe deflects due to off-axis forces acting on its tip by the surrounding structure. We tested the performance of the prototype into a 10% wt gelatine phantom, in terms of the predictability of the steering direction and the controllability of the final position after steering inside the substrate. The results showed that the probe steered in the direction of the retracted wire and that the final position varied from small deflections from the straight path when the wires were slightly retracted, to sharp curvatures for large wire retraction. The probe could be used in various applications, from cases where only a small correction of the path in one direction is needed to cases where the path to be followed includes obstacles and curves in multiple directions.
直径小于 1 毫米的针用于各种医疗应用，以限制在手术过程中并发症和患者不适的风险。除了直径小之外，针的可操纵性是准确和精确到达位于身体内部深处的目标的重要特性。在本文中，我们提出了一种 0.5 毫米的原型探头，它能够在不需要轴向旋转的情况下在三维（3D）方向上进行转向。原型由三根直径为 0.125 毫米的镍钛诺丝（每条丝）组成，具有预弯曲的尖端。这些线由不锈钢管保持在一起。每根线都夹在一个块上，该块沿着丝杠平移，丝杠的旋转由连接在丝杠远端的轮子控制。当一根或两根线缩回时，尖端会弯曲。当探针穿过柔软的固体结构（例如软组织或软组织模型）时，由于周围结构作用在尖端上的偏轴力，探针会发生偏转。我们在 10%wt 明胶模型中测试了原型的性能，以转向方向的可预测性和在基质内转向后的最终位置的可控性为指标。结果表明，探针沿着缩回线的方向转向，并且最终位置从缩回线时的微小偏离直线路径的位置变化到较大缩回线时的急剧弯曲位置。探针可用于各种应用，从仅需要在一个方向上进行小的路径修正的情况到需要遵循包括多个方向的障碍物和曲线的路径的情况。
