Swimming dynamics of screw-shaped untethered magnetic robots in confined spaces.

IF 5.2 2区工程技术 Q1 ENGINEERING, MECHANICAL

Nonlinear Dynamics Pub Date : 2025-01-01 Epub Date: 2025-08-11 DOI:10.1007/s11071-025-11646-7

Luuc de Jongh, Anke Klingner, Leendert-Jan W Ligtenberg, Marcus C J de Boer, Jaap van der Kooij, Roger Lomme, Dorothee Wasserberg, H Remco Liefers, Pascal Jonkheijm, Michiel C Warlé, Islam S M Khalil

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引用次数: 0

Abstract

In confined environments, the propulsion speed of torque-driven helical untethered magnetic robots (UMRs) depends on vessel diameter and helical pitch. This phenomenon likely affects the swimming speed of these robots when navigating in vivo within blood vessels. Achieving a consistent swimming speed across a range of vessel diameters is therefore essential for precise control of UMRs. With this goal, we investigate how vessel diameter and helical pitch influence UMR propulsion to identify optimal robot designs. UMRs from two groups-fixed length (FL) and fixed wave (FW)-were analyzed. In the FW group, longer robots achieved higher speeds in larger vessels due to better vessel guidance, whereas shorter robots performed best in medium-sized vessels. The FL group showed peak speeds at intermediate normalized wavenumbers ( $ν \approx 1$ to 1.8), significantly influenced by robot geometry and vessel confinement. Normalized wavenumber affected swimming speed and stability, with maximum efficiency at $ν \approx 1$ and stability increasing with higher wavenumbers. Swimming performance was modeled using Stokeslets method and additional effects were considered by correction factors to improve agreement of experimental and modeling results. Ex vivo tests under physiological conditions demonstrated clear performance differences between robust (FL-9 ( $ν = 2.3$ ), FW-5 ( $ν = 2$ )) and unstable swimmers, with robust designs showing consistent correlation between phantom and ex vivo trials. Unstable designs exhibited unpredictable behavior, emphasizing the importance of specific design parameters for stability and maneuverability. These findings highlight critical design factors-such as the normalized wavenumber, body length, and degree of vessel confinement-that are essential for enhancing UMR propulsion efficiency and control consistency, which are fundamental for successful navigation in targeted vascular biomedical applications.

Supplementary information: The online version contains supplementary material available at 10.1007/s11071-025-11646-7.

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螺旋形无系绳磁性机器人在密闭空间中的游动动力学。

在密闭环境下，力矩驱动的螺旋无系绳磁性机器人的推进速度取决于船体直径和螺旋节距。这种现象可能会影响这些机器人在血管内游动时的游动速度。因此，在一定的容器直径范围内实现一致的游泳速度对于精确控制umr至关重要。为了实现这一目标，我们研究了容器直径和螺旋节距如何影响UMR推进，以确定最佳机器人设计。对固定长度（FL）组和固定波（FW）组的umr进行分析。在FW组中，由于更好的船舶引导，较长的机器人在大型船舶中获得了更高的速度，而较短的机器人在中型船舶中表现最好。FL组在中间归一化波数（ν≈1至1.8）处显示出峰值速度，受机器人几何形状和容器约束的显著影响。归一化波数影响游泳速度和稳定性，在ν≈1时效率最大，稳定性随波数的增加而增加。采用Stokeslets方法对游泳性能进行建模，并通过校正因子考虑附加影响，以提高实验结果与建模结果的一致性。生理条件下的离体试验表明，健步性游泳者（FL-9 （ν = 2.3）、FW-5 (ν = 2)）和不稳定游泳者的表现存在明显差异，健步性设计显示出幻影和离体试验之间的一致相关性。不稳定设计表现出不可预测的行为，强调了特定设计参数对稳定性和可操作性的重要性。这些发现强调了关键的设计因素，如归一化波数、体长和血管受限程度，这些因素对于提高UMR推进效率和控制一致性至关重要，这是在靶向血管生物医学应用中成功导航的基础。补充信息：在线版本包含补充资料，可在10.1007/s11071-025-11646-7获得。

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来源期刊

Nonlinear Dynamics 工程技术-工程：机械

CiteScore

9.00

自引率

17.90%

发文量

966

审稿时长

5.9 months

期刊介绍： Nonlinear Dynamics provides a forum for the rapid publication of original research in the field. The journal’s scope encompasses all nonlinear dynamic phenomena associated with mechanical, structural, civil, aeronautical, ocean, electrical, and control systems. Review articles and original contributions are based on analytical, computational, and experimental methods. The journal examines such topics as perturbation and computational methods, symbolic manipulation, dynamic stability, local and global methods, bifurcations, chaos, and deterministic and random vibrations. The journal also investigates Lie groups, multibody dynamics, robotics, fluid-solid interactions, system modeling and identification, friction and damping models, signal analysis, and measurement techniques.