Propulsion and energetics of a minimal magnetic microswimmer

In this manuscript we describe the realization of a minimal hybrid microswimmer, composed of a ferromagnetic nanorod and a paramagnetic microsphere. The unbounded pair is propelled in water upon application of a swinging magnetic field that induces a periodic relative movement of the two composing e...

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Bibliographic Details
Published in:Soft matter 2020-07, Vol.16 (28), p.6673-6682
Main Authors: Calero, Carles, García-Torres, José, Ortiz-Ambriz, Antonio, Sagués, Francesc, Pagonabarraga, Ignacio, Tierno, Pietro
Format: Article
Language:English
Subjects:
Computer simulation
Ferromagnetism
Magnetic fields
Mathematical models
Nanorods
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Summary:In this manuscript we describe the realization of a minimal hybrid microswimmer, composed of a ferromagnetic nanorod and a paramagnetic microsphere. The unbounded pair is propelled in water upon application of a swinging magnetic field that induces a periodic relative movement of the two composing elements, where the nanorod rotates and slides on the surface of the paramagnetic sphere. When taken together, the processes of rotation and sliding describe a finite area in the parameter space, which increases with the frequency of the applied field. We develop a theoretical approach and combine it with numerical simulations, which allow us to understand the dynamics of the propeller and explain the experimental observations. Furthermore, we demonstrate a reversal of the microswimmer velocity by varying the length of the nanorod, as predicted by the model. Finally, we determine theoretically and in experiments the Lighthill's energetic efficiency of this minimal magnetic microswimmer. We investigate the propulsion and energetic efficiency of a hybrid microswimmer composed of a ferromagnetic nanorod and a paramagnetic microsphere.
ISSN:1744-683X
1744-6848
DOI:10.1039/d0sm00564a