Fu Henry C, Jabbarzadeh Mehdi, Meshkati Farshad
Department of Mechanical Engineering, University of Nevada at Reno, Reno, Nevada 89557, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2015 Apr;91(4):043011. doi: 10.1103/PhysRevE.91.043011. Epub 2015 Apr 17.
Recently, there has been much progress in creating microswimmers or microrobots capable of controlled propulsion in fluidic environments. These microswimmers have numerous possible applications in biomedicine, microfabrication, and sensing. One type of effective microrobot consists of rigid magnetic helical microswimmers that are propelled when rotated at a range of frequencies by an external rotating magnetic field. Here we focus on investigating which magnetic dipoles and helical geometries optimally lead to linear velocity-frequency response, which may be desirable for the precise control and positioning of microswimmers. We identify a class of optimal magnetic field moments. We connect our results to the wobbling behavior previously observed and studied in helical microswimmers. In contrast to previous studies, we find that when the full helical geometry is taken into account, wobble-free motion is not possible for magnetic fields rotating in a plane. Our results compare well quantitatively to previously reported experiments, validating the theoretical analysis method. Finally, in the context of our optimal moments, we identify helical geometries for minimization of wobbling and maximization of swimming velocities.
最近，在制造能够在流体环境中实现可控推进的微型游泳器或微型机器人方面取得了很大进展。这些微型游泳器在生物医学、微制造和传感领域有许多潜在应用。一种有效的微型机器人由刚性磁性螺旋微型游泳器组成，当通过外部旋转磁场在一定频率范围内旋转时，它们会被推动前进。在这里，我们专注于研究哪些磁偶极和螺旋几何形状能最佳地导致线性速度-频率响应，这对于微型游泳器的精确控制和定位可能是理想的。我们确定了一类最佳磁场矩。我们将我们的结果与先前在螺旋微型游泳器中观察和研究的摆动行为联系起来。与先前的研究不同，我们发现当考虑完整的螺旋几何形状时，对于在平面内旋转的磁场，无摆动运动是不可能的。我们的结果在定量上与先前报道的实验结果吻合良好，验证了理论分析方法。最后，在我们的最佳矩的背景下,我们确定了使摆动最小化和游泳速度最大化的螺旋几何形状。
