Unidirectional Propulsion of Planar Magnetic Nanomachines

Abstract

Steering of magnetic nano-/microhelices by a rotating magnetic field is considered as a promising technique for controlled navigation of tiny objects through viscous fluidic environments. It has been recently demonstrated that simple geometrically achiral planar structures can also be steered efficiently. Such planar propellers are interesting for practical reasons, as they can be mass-fabricated using standard micro/nanolithography techniques. While planar magnetic structures are prone to inplane magnetization, under the effect of an in-plane rotating magnetic field, they exhibit, at most, propulsion due to spontaneous symmetry breaking, i.e., they can propel either parallel or antiparallel to the rotation axis of the field depending on their initial orientation. Here we demonstrate that actuation by a conically rotating magnetic field (i.e., superposition of in-plane rotating field and constant field orthogonal to it) can yield efficient unidirectional propulsion of planar and magnetized in-plane structures. In particular, we found that a highly symmetrical V-shape magnetized along its symmetry axis which exhibits no net propulsion in in-plane rotating field, exhibits unidirectional in-sync propulsion with a constant (frequency-independent) velocity when actuated by the conically rotating field.

Development of 2D MOF-Based Microrobots under Annealing Treatment and Their Biomedical Application

“…To reduce the time and cost of the fabrication, the achiral planar design , was adopted for the MOF-based microrobots. Achiral planar microrobots have been demonstrated to have excellent swimming capability in bulk fluid and are capable of rolling motion on surfaces. − Based on the simplicity and scalability of manufacturing achiral planar microrobots, the arch-shaped two-dimensional (2D) microrobot precursors will be mass-manufactured using photolithography and physical vapor deposition. Then, the precursors will be coordinated with zeolitic imidazolium frameworks 8 (ZIF-8), resulting in MOF-based microrobots with high specific surface area, good biocompatibility, and wireless magnetic propulsion.…”

Stop-Flow Lithography for the Continuous Production of Degradable Hydrogel Achiral Crescent Microswimmers

“…In previous work, the swimming ability of crescent microswimmers has been proved theoretically and demonstrated experimentally [ 28 , 29 , 30 ]. To further quantify the swimming ability of the hydrogel crescent microswimmers on swimming performance, magnetic drive tests were performed.…”

Immunomodulation and delivery of macrophages using nano-smooth drug-loaded magnetic microrobots for dual targeting cancer therapy

“…Magnetically driven achiral planar microrobots have garnered attention owing to their effective propulsive ability under rotating or conical magnetic field actuation ( Cheang et al., 2014b , 2017 ; Cohen et al., 2019 ). In addition, propellers with achiral planar shapes offer the advantage of scalability and mass fabrication by circumventing the need to fabricate complex 3D structures while maintaining swimming speed that can compete with helical microrobots ( Mirzae et al., 2018 ).…”