On-Surface Locomotion of Particle Based Microrobots Using Magnetically Induced Oscillation

Abstract

The low Reynolds number condition presents a fundamental constraint on designing locomotive mechanisms for microscale robots. We report on the use of an oscillating magnetic field to induce on-surface translational motion of particle based microrobots. The particle based microrobots consist of microparticles, connected in a chain-like manner using magnetic self-assembly, where the non-rigid connections between the particles provide structural flexibility for the microrobots. Following the scallop theorem, the oscillation of flexible bodies can lead to locomotion at low Reynolds numbers, similar to the beating motion of sperm flagella. We characterized the velocity profiles of the microrobots by measuring their velocities at various oscillating frequencies. We also demonstrated the directional steering capabilities of the microrobots. This work will provide insights into the use of oscillation as a viable mode of locomotion for particle based microrobots near a surface.

Propulsion Mechanism of Flexible Microbead Swimmers in the Low Reynolds Number Regime

“…Meanwhile, the L3S1 swimmer exhibited an insignificant deformation because it featured a nearly symmetrical geometry that showed a slight distortion at its short tail. It is noted that magnetic swimmers that are made of microbeads without a chemical link, such as DNA [ 16 ] or streptavidin–biotin binding [ 19 , 21 ] do not retain a stable S-shaped structure under the influence of a higher oscillation frequency. These easily fabricated flexible swimmers have a short, curved shape with limited length, so they generate only limited flexible structure in a strong field strength that oscillates at a moderately high frequency.…”

“…The third group is the one-armed swimmers that are referred to as flexible propellers and generate propulsion using a flexible flagellum fabricated using a DNA linkage [ 16 ] or nanowire [ 17 , 18 ], actuated by an oscillating magnetic field. In recent cases, particle-based magnetic microswimmers were fabricated and manipulated under a rotating magnetic field [ 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. Other proposed methods to develop novel magnetic actuation sperm-like microswimmers have also been demonstrated [ 27 , 28 , 29 ].…”

Optomechanically Actuated Microcilia for Locally Reconfigurable Surfaces

“…Cilia (from the Latin cilium, “eyelash”) are thin, hair‐like structures that cover the inner layer of mammalian trachea for mucus transportation out of the lungs [ 1 ] and cover the outer surface of micro‐organisms (e.g., paramecium) to aid in locomotion, food capture, tactile sensing, and mating reactions. [ 2 ] Numerous studies have focused on replicating these morphologies and exploring artificial cilia for applications in microfluidic propulsion/mixing, [ 3–7 ] surface property modification, [ 8 ] enhancing catalytic reactions, [ 9,10 ] sensing, [ 11–14 ] microrobots/swimmers, [ 15,16 ] object transportation, [ 17–19 ] and cell stimulation. [ 20 ]…”

Modular approach to microswimming

“…Besides Dreyfus and coworkers, there are a few groups interested in connecting particles into colloidal chains of different rigidities. 42,43,48 We specially mention the colloidal chains fabricated by Vutukuri and coworkers of 'zig-zag' configuration (Fig. 1f).…”