Khalil Islam S M, Klingner Anke, Hamed Youssef, Magdanz Veronika, Toubar Mohamed, Misra Sarthak
Department of Biomechanical Engineering, University of Twente, Enschede, Netherlands.
Department of Physics, The German University in Cairo, New Cairo, Egypt.
Front Robot AI. 2019 Jul 31;6:65. doi: 10.3389/frobt.2019.00065. eCollection 2019.
Several microorganisms swim by a beating flagellum more rapidly in solutions with gel-like structure than they do in low-viscosity mediums. In this work, we aim to model and investigate this behavior in low Reynolds numbers viscous heterogeneous medium using soft microrobotic sperm samples. The microrobots are actuated using external magnetic fields and the influence of immersed obstacles on the flagellar propulsion is investigated. We use the resistive-force theory to predict the deformation of the beating flagellum, and the method of regularized Stokeslets for computing Stokes flows around the microrobot and the immersed obstacles. Our analysis and experiments show that obstacles in the medium improves the propulsion even when the Sperm number is not optimal ( ≠ 2.1). Experimental results also show propulsion enhancement for concentration range of 0-5% at relatively low actuation frequencies owing to the pressure gradient created by obstacles in close proximity to the beating flagellum. At relatively high actuation frequency, speed reduction is observed with the concentration of the obstacles.
几种通过鞭毛摆动游动的微生物，在具有凝胶状结构的溶液中比在低粘度介质中游动得更快。在这项工作中，我们旨在使用软微型机器人精子样本，对低雷诺数粘性非均匀介质中的这种行为进行建模和研究。微型机器人由外部磁场驱动，并研究了浸没障碍物对鞭毛推进的影响。我们使用阻力理论来预测摆动鞭毛的变形，并使用正则化斯托克斯子方法来计算微型机器人和浸没障碍物周围的斯托克斯流。我们的分析和实验表明，即使精子数量不是最优值（≠2.1），介质中的障碍物也能改善推进效果。实验结果还表明，由于靠近摆动鞭毛的障碍物产生的压力梯度，在相对较低的驱动频率下，浓度范围为0-5%时推进力会增强。在相对较高的驱动频率下，随着障碍物浓度的增加，速度会降低。
