Magnetic Control of Ferrofluid Droplet Adhesion in Shear Flow and on Inclined Surfaces

Cui, G.; Jacobi, Ian

doi:10.1021/acs.langmuir.0c02369

Cited by 7 publications

(3 citation statements)

References 50 publications

(78 reference statements)

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“…It must be noted that the saturated value of ξ max is increasing with the increase of polymer concentrations. One of the potential reason for the initial linear increase of ξ max with Bo m is due to the linear magnetization of the ferrofluid droplet , in the low field regime. In a previous report, it has been shown that PEG chains may entangle Fe 3 O 4 nanoparticles to form a particle–polymer chain mesh.…”

Section: Resultsmentioning

confidence: 99%

Magneto-Elastic Effect in Non-Newtonian Ferrofluid Droplets Impacting Superhydrophobic Surfaces

2021

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In this article, we propose, with the aid of detailed experiments and scaling analysis, the existence of magneto-elastic effects in the impact hydrodynamics of non-Newtonian ferrofluid droplets on superhydrophobic surfaces in the presence of a magnetic field. The effects of magnetic Bond number (Bo m), Weber number (We), polymer concentration, and magnetic nanoparticle (Fe3O4) concentration in the ferrofluids were investigated. In comparison to Newtonian ferrofluid droplets, addition of polymers caused rebound suppression of the droplets relatively at lower Bo m for a fixed magnetic nanoparticle concentration and We. We further observed that for a fixed polymer concentration and We, increasing magnetic nanoparticle concentration also triggers earlier rebound suppression with increasing Bo m. In the absence of the magnetic nanoparticles, the non-Newtonian droplets do not show rebound suppression for the range of Bo m investigated. Likewise, the Newtonian ferrofluids show rebound suppression at large Bo m. This intriguing interplay of elastic effects of polymer chains and the magnetic nanoparticles, dubbed as the magneto-elastic effect, is noted to lead to the rebound suppression. We establish a scaling relationship to show that the rebound suppression is observed as a manifestation of the onset of magneto-elastic instability only when the proposed magnetic Weissenberg number (Wi m) exceeds unity. We also put forward a phase map to identify the various regimes of impact ferrohydrodynamics of such droplets and the occurrence of the magneto-elastic effect.

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Section: Resultsmentioning

confidence: 99%

Magneto-Elastic Effect in Non-Newtonian Ferrofluid Droplets Impacting Superhydrophobic Surfaces

2021

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“…Concomitant with the progress in microfluidic technologies, droplet microfluidics realizes the flow control of microdroplets and builds a new platform for biological and medical research. Until now, a variety of droplet control methods such as electrowetting [13,14], optical tweezers [15,16], acoustic manipulation [17], and magnetic manipulation [18][19][20] have been developed to transport, sort, split, merge and mix droplets.…”

Section: Introductionmentioning

confidence: 99%

Recent Advances in Magnetically Actuated Droplet Manipulation for Biomedical Applications

Li,

Su,

Liu

et al. 2024

Magnetochemistry

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The manipulation of droplets plays a vital role in biomedicine, chemistry, and hydromechanics, especially in microfluidics. Magnetic droplet manipulation has emerged as a prominent and advanced technique in comparison to other modes such as dielectric infiltration, optical radiation, and surface acoustic waves. Its notable progress is attributed to several advantages, including excellent biocompatibility, remote and non-contact control, and instantaneous response. This review provides a comprehensive overview of recent developments in magnetic droplet manipulation and its applications within the biomedical field. Firstly, the discussion involves an examination of the distinctive features associated with droplet manipulation based on both permanent magnet and electromagnet principles, along with a thorough exploration of the influencing factors impacting magnetic droplet manipulation. Additionally, an in-depth review of magnetic actuation mechanisms and various droplet manipulation methods is presented. Furthermore, the article elucidates the biomedical applications of magnetic droplet manipulation, particularly its role in diagnostic assays, drug discovery, and cell culture. Finally, the highlights and challenges of magnetic droplet manipulation in biomedical applications are described in detail.

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“…The critical flow velocity under different driving frequencies and an external magnetic field can be determined according to the growth rate and decay rate of interface fluctuation. Cui [16] studied the effect of gravity and shear flow on adhesion of magnetic fluid and found that the enhancement of a vertical magnetic field could improve the critical magnetic Bond number and reduce the critical Weber number, which makes the magnetic droplet more susceptible to shear flow. Bohlius [17] deduced the dispersion relationship of interfacial waves in magnetic films under a vertical magnetic field.…”

Section: Introductionmentioning

confidence: 99%

Influence of High Viscosity and Magnetoviscous Effect on the Washout Resistance of Magnetic Fluid

et al. 2023

Magnetochemistry

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Magnetic fluid seals have long been thought to be a successful sealing form while sealing liquids are always a challenge. The instability of the liquid–liquid interface under the washout has become the key technical problem that hinders the realization of sealing liquid. This work mainly presents an experimental study about the influence of high viscosity and magnetoviscous effects on washout resistance. Three engine oil-based magnetic fluids of different viscosities were prepared with two kinds of surfactants. The magnetoviscous effects of the prepared magnetic fluids under different working conditions were found through rheological experiments. The viscosity of the three samples decreased at most by about 100 times with the shear rate increasing. An experimental platform was designed and built for the washout tests. The entire process of magnetic fluids being washed away was obtained experimentally. The magnetic fluid of higher viscosity can remain stationary with lower magnetic force. The quantitative results show that the viscosity of the magnetic fluid has a significant influence on washout resistance under a magnetic field.

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Magnetic Control of Ferrofluid Droplet Adhesion in Shear Flow and on Inclined Surfaces

Cited by 7 publications

References 50 publications

Magneto-Elastic Effect in Non-Newtonian Ferrofluid Droplets Impacting Superhydrophobic Surfaces

Magneto-Elastic Effect in Non-Newtonian Ferrofluid Droplets Impacting Superhydrophobic Surfaces

Recent Advances in Magnetically Actuated Droplet Manipulation for Biomedical Applications

Influence of High Viscosity and Magnetoviscous Effect on the Washout Resistance of Magnetic Fluid

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