Gürbüz Ali, Qin Ke, Abbott Jake J, Pak On Shun
Department of Mechanical Engineering, Santa Clara University, Santa Clara, CA 95053, USA.
Department of Mechanical Engineering and the Robotics Center, University of Utah, Salt Lake City, UT 84112, USA.
Soft Matter. 2023 Sep 27;19(37):7100-7108. doi: 10.1039/d3sm00464c.
The elastohydrodynamic interaction between an elastic filament and its surrounding fluid was exploited to develop the first microswimmers. These flexible microswimmers are typically actuated magnetically at one end and their propulsion behavior is relatively well understood. In this work, we move beyond the traditional single-end actuation setup and explore the propulsion characteristics of an elastic filament driven by magnetic torques at both ends. We report the emergence of new modes of propulsion behaviors in different physical regimes, depending on the balance of elastic and viscous forces as well as the arrangement of the magnetic moments at the filament ends. In particular, under the same magnetic actuation, a filament driven at both ends can propel either forward or backward depending on its relative stiffness. Moreover, this new backward propulsion mode can generate a magnitude of propulsion that is unattainable by the traditional single-end actuation setup. We characterize these new propulsion behaviors and provide some physical insights into how they emerge from the complex interplay between viscous and elastic forces and magnetic actuation in various configurations. Taken together, these findings could guide the development of soft microrobots with enhanced propulsion performance and maneuverability for future biomedical applications.
弹性细丝与其周围流体之间的弹性流体动力相互作用被用于开发第一代微型游泳器。这些柔性微型游泳器通常在一端通过磁力驱动，其推进行为已得到相对较好的理解。在这项工作中，我们超越了传统的单端驱动设置，探索两端由磁转矩驱动的弹性细丝的推进特性。我们报告了在不同物理状态下出现的新的推进行为模式，这取决于弹性力和粘性力的平衡以及细丝两端磁矩的排列。特别是，在相同的磁驱动下，两端驱动的细丝根据其相对刚度可以向前或向后推进。此外，这种新的向后推进模式可以产生传统单端驱动设置无法实现的推进力大小。我们对这些新的推进行为进行了表征，并对它们如何从粘性力、弹力和各种配置中的磁驱动之间的复杂相互作用中产生提供了一些物理见解。综上所述，这些发现可以指导具有更高推进性能和可操作性的软微型机器人的开发，以用于未来的生物医学应用。
