Rotating magnetic nanorods detect minute fluctuations of magnetic field

Palkar, Vaibhav; Aprelev, Pavel; Salamatin, A. A.; Brasovs, Artis; Kuksenok, Olga; Kornev, Konstantin G.

doi:10.1103/physreve.100.051101

Cited by 5 publications

(8 citation statements)

References 19 publications

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“…An out of plane motionprecession -was predicted for soft magnetic particles in a rotating field 14 . Later this was observed experimentally for ferromagnetic nanorods 15 and recently elaborated in detail both experimentally and theoretically by Palkar et al 6 , where they show how a ferromagnetic rod beyond a critical frequency can have two possible regimes: unstable in-plane asynchronous back and forth motion and stable synchronous precession. It is worth noting that the critical frequency f c both for ferromagnetic rods and filaments is proportional to the magnetic field H and inversely proportional to the length squared L 2 .…”

Section: Discussionmentioning

confidence: 77%

“…This situation is structurally unstable and at some small perturbation, for example, due to the Earth's magnetic field, only the precessional regime survives. For a rigid ferromagnetic rod this was recently illustrated experimentally 6 . Previously we have numerically studied the planar regime of a flexible ferromagnetic rod under the action of a rotating magnetic field 7 .…”

Section: Introductionmentioning

confidence: 75%

“…Torque is once again large enough to cause a synchronous rotation, but now for a filament that is deformed in 3D. At least the appearance of stable precessing states for ferromagnetic rods is explained by analyzing the effect of small perturbations on the phase portrait 6 .…”

Section: Discussionmentioning

confidence: 99%

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3D motion of flexible ferromagnetic filaments under a rotating magnetic field

2020

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Ferromagnetic filaments in a rotating magnetic field are studied both numerically and experimentally. The filaments are made from micron-sized ferromagnetic particles linked with DNA strands. It is found that at low frequencies of the rotating field a filament rotates synchronously with the field and beyond a critical frequency it undergoes a transition to a three dimensional regime. In this regime the tips of the filament rotate synchronously with the field on circular trajectories in the plane parallel to the plane of the rotating field. The characteristics of this motion found numerically match the experimental data and allow us to obtain the physical properties of such filaments. We also discuss the differences in behaviour between magnetic rods and filaments and the applicability of filaments in mixing. J o u r n a l N a me , [ y e a r ] , [ v o l . ] ,1-7 | 1 arXiv:2003.03737v1 [cond-mat.soft]

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Section: Discussionmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 75%

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3D motion of flexible ferromagnetic filaments under a rotating magnetic field

2020

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“…The lack of viscosity data hinders rigorous analysis of the energy demands for flying insects. To fill this gap, we characterized haemolymph viscosity of the adults of 14 species of Lepidoptera by applying magnetic rotational spectroscopy (MRS) with magnetic nanorods [7,27,28]. To put the viscosity data into the context of haemolymph circulation, we used micro-computed tomography scans to characterize the structure of the thoracic haemolymph pathways of hawkmoths.…”

Section: Introductionmentioning

confidence: 99%

Haemolymph viscosity in hawkmoths and its implications for hovering flight

et al. 2023

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Viscosity determines the resistance of haemolymph flow through the insect body. For flying insects, viscosity is a major physiological parameter limiting flight performance by controlling the flow rate of fuel to the flight muscles, circulating nutrients and rapidly removing metabolic waste products. The more viscous the haemolymph, the greater the metabolic energy needed to pump it through confined spaces. By employing magnetic rotational spectroscopy with nickel nanorods, we showed that viscosity of haemolymph in resting hawkmoths (Sphingidae) depends on wing size non-monotonically. Viscosity increases for small hawkmoths with high wingbeat frequencies, reaches a maximum for middle-sized hawkmoths with moderate wingbeat frequencies, and decreases in large hawkmoths with slower wingbeat frequencies but greater lift. Accordingly, hawkmoths with small and large wings have viscosities approaching that of water, whereas hawkmoths with mid-sized wings have more than twofold greater viscosity. The metabolic demands of flight correlate with significant changes in circulatory strategies via modulation of haemolymph viscosity. Thus, the evolution of hovering flight would require fine-tuned viscosity adjustments to balance the need for the haemolymph to carry more fuel to the flight muscles while decreasing the viscous dissipation associated with its circulation.

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“…Ferromagnetic nanorods are thin elongated units which display a permanent magnetic moment and thus can be manipulated and torqued by relatively low intensity external fields. − The small size and the strong magnetization of these nanostructures are two features that have been exploited in several applications to date. Magnetic nanorods have not only been used in microrheology − or as magnetic field sensors − but also implemented in several biomedical − and photonic , systems. Recent years have witnessed a surge of interest in investigating the dynamics of these anisotropic units when driven by time-dependent magnetic fields: i.e., when they behave as steerable nanopropellers. − Further on, the nanorod rotational movement can be used to trap and deliver microscopic cargoes, a feature that makes these nanoswimmers of great interest for different emerging technologies, including drug delivery or noninvasive microsurgery. , …”

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confidence: 99%

Unveiling the Rolling to Kayak Transition in Propelling Nanorods with Cargo Trapping and Pumping

et al. 2023

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Magnetic nanorods driven by rotating fields in water can be rapidly steered along any direction while generating strong and localized hydrodynamic flow fields. Here we show that, when raising the frequency of the rotating field, these nanopropellers undergo a dynamic transition from a rolling to a kayak-like motion due to the increase in viscous drag and acquire a finite inclination angle with respect to the plane perpendicular to the bottom surface. We explain these experimental observations with a theoretical model which considers the nanorod as a pair of ferromagnetic particles hydrodynamically interacting with a close stationary surface. Further, we quantify how efficiently microscopic cargoes can be trapped or expelled from the moving nanorod and use numerical simulations to unveil the generated hydrodynamic flow field. These propulsion regimes can be implemented in microfluidic devices to perform precise operations based on the selective sorting of microscopic cargoes.

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Rotating magnetic nanorods detect minute fluctuations of magnetic field

Cited by 5 publications

References 19 publications

3D motion of flexible ferromagnetic filaments under a rotating magnetic field

3D motion of flexible ferromagnetic filaments under a rotating magnetic field

Haemolymph viscosity in hawkmoths and its implications for hovering flight

Unveiling the Rolling to Kayak Transition in Propelling Nanorods with Cargo Trapping and Pumping

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