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Surface-Chemistry-Mediated Control of Individual Magnetic Helical Microswimmers in a Swarm.

  • Wang X Institute of Robotics and Intelligent Systems , ETH Zurich , Tannenstrasse 3 , CH-8092 Zurich , Switzerland.
  • Hu C Institute of Robotics and Intelligent Systems , ETH Zurich , Tannenstrasse 3 , CH-8092 Zurich , Switzerland.
  • Schurz L Institute of Robotics and Intelligent Systems , ETH Zurich , Tannenstrasse 3 , CH-8092 Zurich , Switzerland.
  • De Marco C Institute of Robotics and Intelligent Systems , ETH Zurich , Tannenstrasse 3 , CH-8092 Zurich , Switzerland.
  • Chen X Institute of Robotics and Intelligent Systems , ETH Zurich , Tannenstrasse 3 , CH-8092 Zurich , Switzerland.
  • Pané S Institute of Robotics and Intelligent Systems , ETH Zurich , Tannenstrasse 3 , CH-8092 Zurich , Switzerland.
  • Nelson BJ Institute of Robotics and Intelligent Systems , ETH Zurich , Tannenstrasse 3 , CH-8092 Zurich , Switzerland.
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  • 2018-05-26
Published in:
  • ACS nano. - 2018
magnetic helical microswimmers
selective control
surface functionalization
swarm control
wettability
Biomimetics
Flagella
Hydrophobic and Hydrophilic Interactions
Magnetic Fields
Sulfhydryl Compounds
Sulfides
Surface Properties
Wettability
English Magnetic helical microswimmers, also known as artificial bacterial flagella (ABFs), perform 3D navigation in various liquids under low-strength rotating magnetic fields by converting rotational motion to translational motion. ABFs have been widely studied as carriers for targeted delivery and release of drugs and cells. For in vivo/ in vitro therapeutic applications, control over individual groups of swimmers within a swarm is necessary for several biomedical applications such as drug delivery or small-scale surgery. In this work, we present the selective control of individual swimmers in a swarm of geometrically and magnetically identical ABFs by modifying their surface chemistry. We confirm experimentally and analytically that the forward/rotational velocity ratio of ABFs is independent of their surface coatings when the swimmers are operated below their step-out frequency (the frequency requiring the entire available magnetic torque to maintain synchronous rotation). We also show that ABFs with hydrophobic surfaces exhibit larger step-out frequencies and higher maximum forward velocities compared to their hydrophilic counterparts. Thus, selective control of a group of swimmers within a swarm of ABFs can be achieved by operating the selected ABFs at a frequency that is below their step-out frequencies but higher than the step-out frequencies of unselected ABFs. The feasibility of this method is investigated in water and in biologically relevant solutions. Selective control is also demonstrated inside a Y-shaped microfluidic channel. Our results present a systematic approach for realizing selective control within a swarm of magnetic helical microswimmers.
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  • English
Open access status
green
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https://sonar.ch/global/documents/273987
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