Characterization of Flagellar Propulsion of Soft Microrobotic Sperm in a Viscous Heterogeneous Medium

Islam S M Khalil; Anke Klingner; Youssef Hamed; Veronika Magdanz; Mohamed Toubar; Sarthak Misra

doi:10.3389/frobt.2019.00065

Characterization of Flagellar Propulsion of Soft Microrobotic Sperm in a Viscous Heterogeneous Medium

Front Robot AI. 2019 Jul 31:6:65. doi: 10.3389/frobt.2019.00065. eCollection 2019.

Authors

Islam S M Khalil¹, Anke Klingner², Youssef Hamed², Veronika Magdanz³, Mohamed Toubar², Sarthak Misra^{1

4}

Affiliations

¹ Department of Biomechanical Engineering, University of Twente, Enschede, Netherlands.
² Department of Physics, The German University in Cairo, New Cairo, Egypt.
³ Applied Zoology, Dresden University of Technology, Dresden, Germany.
⁴ Department of Biomedical Engineering, University Medical Center Groningen, University of Groningen, Groningen, Netherlands.

Abstract

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 (S _p ≠ 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.

Keywords: Stokeslets; flagellar propulsion; heterogeneous; magnetic; modeling; resistive-force theory; robotic sperm.