title: Optimal Length of Low Reynolds Number Nanopropellers.
abstract: Locomotion in fluids at the nanoscale is dominated by viscous drag. One efficient propulsion scheme is to use a weak rotating magnetic field that drives a chiral object. From bacterial flagella to artificial drills, the corkscrew is a universally useful chiral shape for propulsion in viscous environments. Externally powered magnetic micro- and nanomotors have been recently developed that allow for precise fuel-free propulsion in complex media. Here, we combine analytical and numerical theory with experiments on nanostructured screw-propellers to show that the optimal length is surprisingly short-only about one helical turn, which is shorter than most of the structures in use to date. The results have important implications for the design of artificial actuated nano- and micropropellers and can dramatically reduce fabrication times, while ensuring optimal performance.
authors.affiliation: †Max Planck Institute for Intelligent Systems, Heisenbergstraße 3, 70569 Stuttgart, Germany.|‡Institute for Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Walker
authors.affiliation: ‡Institute for Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Kübler
authors.affiliation: §Department of Chemical Engineering and Russel Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel.
authors.forename: K I
authors.initials: KI
authors.lastname: Morozov
authors.affiliation: †Max Planck Institute for Intelligent Systems, Heisenbergstraße 3, 70569 Stuttgart, Germany.|‡Institute for Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Fischer
authors.affiliation: §Department of Chemical Engineering and Russel Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel.
authors.forename: A M
authors.initials: AM
authors.lastname: Leshansky
keywords: Nanopropellers; glancing angle deposition (GLAD); magnetic nanomotors; microswimmers; rotating magnetic field; viscous hydrodynamics