Biocompatible, accurate, and fully autonomous: a sperm-driven micro-bio-robot

Abstract

We study the magnetic-based motion control of a sperm-flagella driven Micro-Bio-Robot (MBR), and demonstrate precise point-to-point closed-loop motion control under the influence of the controlled magnetic field lines. This MBR consists of a bovine spermatozoon that is captured inside Ti/Fe nanomembranes. The nanomembranes are rolled-up into a 50 μm long microtube with a diameter of 5-8 μm. Our MBR is self-propelled by the sperm cell and guided using the magnetic torque exerted on the magnetic dipole of its rolled-up microtube. The self-propulsion force provided by the sperm cell allows the MBR to move at an average velocity of 25 ±10 μm/s towards a reference position, whereas the magnetic dipole moment and the controlled weak magnetic fields (approximately 1.39 mT) allow for the localization of the MBR within the vicinity of reference positions with an average region-of-convergence of 90 ±40μm. In addition, we experimentally demonstrate the guided motion of the MBR towards a magnetic microparticle with applications towards targeted drug delivery and microactuation.