title: Fast Magnetic Micropropellers with Random Shapes.
abstract: Studying propulsion mechanisms in low Reynolds number fluid has implications for many fields, ranging from the biology of motile microorganisms and the physics of active matter to micromixing in catalysis and micro- and nanorobotics. The propulsion of magnetic micropropellers can be characterized by a dimensionless speed, which solely depends on the propeller geometry for a given axis of rotation. However, this dependence has so far been only investigated for helical propeller shapes, which were assumed to be optimal. In order to explore a larger variety of shapes, we experimentally studied the propulsion properties of randomly shaped magnetic micropropellers. Surprisingly, we found that their dimensionless speeds are high on average, comparable to previously reported nanofabricated helical micropropellers. The highest dimensionless speed we observed is higher than that of any previously reported propeller moving in a low Reynolds number fluid, proving that physical random shape generation can be a viable optimization strategy.
authors.affiliation: Department of Biomaterials and ‡Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces , Science Park Golm, 14424 Potsdam, Germany.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Vach
authors.affiliation: Department of Biomaterials and ‡Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces , Science Park Golm, 14424 Potsdam, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Fratzl
authors.affiliation: Department of Biomaterials and ‡Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces , Science Park Golm, 14424 Potsdam, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Klumpp
authors.affiliation: Department of Biomaterials and ‡Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces , Science Park Golm, 14424 Potsdam, Germany.
authors.forename: Damien
authors.initials: D
authors.lastname: Faivre
keywords: Nanomachines; magnetic actuation; micropropellers; microswimmers; nanomotors; nanopropellers