scholarly journals Droplet-Based Microfluidic Preparation of Shape-Variable Alginate Hydrogel Magnetic Micromotors

Nanomaterials ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 115
Author(s):  
Cheng Zhang ◽  
Yong Wang ◽  
Yuduo Chen ◽  
Xing Ma ◽  
Wenjun Chen
Keyword(s):  
Magnetic Field ◽  
Biomedical Applications ◽  
Magnetic Field Gradient ◽  
Rotating Magnetic Field ◽  
Alginate Hydrogel ◽  
Spherical Droplet ◽  
Shape Variable ◽  
Hydrogel Microparticles ◽  
The Magnetic Field ◽  
Spherical Microparticles

This article introduces a facile droplet-based microfluidic method for the preparation of Fe3O4-incorporated alginate hydrogel magnetic micromotors with variable shapes. By using droplet-based microfluidics and water diffusion, monodisperse (quasi-)spherical microparticles of sodium alginate and Fe3O4 (Na-Alg/Fe3O4) are obtained. The diameter varies from 31.9 to 102.7 µm with the initial concentration of Na-Alginate in dispersed fluid ranging from 0.09 to 9 mg/mL. Calcium chloride (CaCl2) is used for gelation, immediately transforming Na-Alg/Fe3O4 microparticles into Ca-Alginate hydrogel microparticles incorporating Fe3O4 nanoparticles, i.e., Ca-Alg/Fe3O4 micromotors. Spherical, droplet-like, and worm-like shapes are yielded depending on the concentration of CaCl2, which is explained by crosslinking and anisotropic swelling during the gelation. The locomotion of Ca-Alg/Fe3O4 micromotors is activated by applying external magnetic fields. Under the rotating magnetic field (5 mT, 1–15 Hz), spherical Ca-Alg/Fe3O4 micromotors exhibit an average advancing velocity up to 158.2 ± 8.6 µm/s, whereas worm-like Ca-Alg/Fe3O4 micromotors could be rotated for potential advancing. Under the magnetic field gradient (3 T/m), droplet-like Ca-Alg/Fe3O4 micromotors are pulled forward with the average velocity of 70.7 ± 2.8 µm/s. This article provides an inspiring and timesaving approach for the preparation of shape-variable hydrogel micromotors without using complex patterns or sophisticated facilities, which holds potential for biomedical applications such as targeted drug delivery.

scholarly journals Remote manipulation of magnetic nanoparticles using magnetic field gradient to promote cancer cell death

2018 ◽  
Author(s):  
Mahendran Subramanian ◽  
Arkadiusz Miaskowski ◽  
Stuart Iain Jenkins ◽  
Jenson Lim ◽  
Jon Dobson
Keyword(s):  
Magnetic Field ◽  
Magnetic Nanoparticles ◽  
Field Gradient ◽  
Biomedical Applications ◽  
Magnetic Field Gradient ◽  
Field Source ◽  
Remote Manipulation ◽  
Cancer Cell Death ◽  
The Magnetic Field

AbstractThe manipulation of magnetic nanoparticles (MNPs) using an external magnetic field, has been demonstrated to be useful in various biomedical applications. Some techniques have evolved utilizing this non-invasive external stimulus but the scientific community widely adopts few, and there is an excellent potential for more novel methods. The primary focus of this study is on understanding the manipulation of MNPs by a time-varying static magnetic field and how this can be used, at different frequencies and displacement, to manipulate cellular function. Here we explore, using numerical modeling, the physical mechanism which underlies this kind of manipulation, and we discuss potential improvements which would enhance such manipulation with its use in biomedical applications, i.e., increasing the MNP response by improving the field parameters. From our observations and other related studies, we infer that such manipulation depends mostly on the magnetic field gradient, the magnetic susceptibility and size of the MNPs, the magnet array oscillating frequency, the viscosity of the medium surrounding MNPs, and the distance between the magnetic field source and the MNPs. Additionally, we demonstrate cytotoxicity in neuroblastoma (SH-SY5Y) and hepatocellular carcinoma (HepG2) cells in vitro. This was induced by incubation with MNPs, followed by exposure to a magnetic field gradient, physically oscillating at various frequencies and displacement amplitudes. Even though this technique reliably produces MNP endocytosis and/or cytotoxicity, a better biophysical understanding is required to develop the mechanism used for this precision manipulation of MNPs, in vitro.

scholarly journals Magnetorheological Fluids Behaviour in Oscillatory Compression Squeeze: Experimental Testing and Analysis

2019 ◽  
Vol 13 (4) ◽  
pp. 221-225
Author(s):  
Wojciech Horak ◽  
Marcin Szczęch ◽  
Bogdan Sapiński
Keyword(s):  
Magnetic Field ◽  
Volume Fraction ◽  
Experimental Testing ◽  
Magnetic Field Gradient ◽  
Particle Volume Fraction ◽  
Excitation Frequency ◽  
Magnetorheological Fluid ◽  
Density Level ◽  
Particle Volume ◽  
The Magnetic Field

Abstract This article deals with experimental testing of magnetorheological fluid (MRF) behaviour in the oscillatory squeeze mode. The authors investigate and analyse the influence of excitation frequency and magnetic field density level on axial force in MRFs that differ in particle volume fraction. The results show that, under certain conditions, the phenomenon of self-sealing can occur as a result of the magnetic field gradient and a vacuum in the working gap of the system.

Precisely mapping the magnetic field gradient in vacuum with an atom interferometer

2010 ◽  
Vol 82 (6) ◽  
Author(s):  
Min-Kang Zhou ◽  
Zhong-Kun Hu ◽  
Xiao-Chun Duan ◽  
Bu-Liang Sun ◽  
Jin-Bo Zhao ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Gradient ◽  
Magnetic Field Gradient ◽  
Atom Interferometer ◽  
The Magnetic Field

Magnetic Nano-Systems in Drug Delivery and Biomedical Applications

2021 ◽  
pp. 663-695
Author(s):  
Saritha R. Shetty ◽  
Archana Upadhya
Keyword(s):  
Magnetic Field ◽  
Drug Delivery ◽  
Targeted Delivery ◽  
Biomedical Applications ◽  
Magnetic Hyperthermia ◽  
Effective Utilization ◽  
Engineering Sciences ◽  
Nanoscale Science ◽  
The Magnetic Field ◽  
Unique Ability

Nanotechnology is that sphere of technology that involves the participation of biology, chemistry, physics, and engineering sciences. Nanoscale science defines the chemistry and physics of structures lying in the range of 1-100 nm. Among the nanosystems researched, magnetic nanosystems are highlighted due their unique ability, which enables their targeting to specific locations on application of an external magnetic field. The exhibited property of these magnetic nanosystems being super-paramagnetism, there is no retention of magnetic property on removal of the magnetic field, thus enabling a reversion of the targeting process. For effective utilization of these nanosystems, they should be reduced to nanosizes, layered with biocompatible entities, stabilized, and functionalized. In the chapter, synthesis and functionalization and stabilization are elucidated. The biomedical applications such as targeted delivery, MRI, magnetic hyperthermia, tissue engineering, gene delivery, magnetic immunotherapy, magnetic detoxification, and nanomagnetic actuation are discussed.

Design and Analysis of a Vibration-Based Magnetoelectric Energy Harvesting Device

2013 ◽  
Vol 722 ◽  
pp. 75-80 ◽  
Author(s):  
Zhang Zhang ◽  
Xian Zhi Dai ◽  
Yong Wang
Keyword(s):  
Magnetic Field ◽  
Cantilever Beam ◽  
Magnetic Circuit ◽  
Magnetic Field Gradient ◽  
Sensor Nodes ◽  
Ambient Vibration ◽  
Gradient Magnetic Field ◽  
Wireless Sensor Nodes ◽  
The Magnetic Field ◽  
Theoretical Results

An energy harvester is presented to harvest ambient vibration energy using a cantilever beam and multiple Terfenol-D/PMN-PT/Terfenol-D laminate magnetoelectric transducers. The harvester uses eight magnets to make up a magnetic circuit arranged on the free end of the cantilever beam. The magnetic circuit can produce a high gradient magnetic field space. The multiple transducers are placed at the high magnetic field gradient position to make the best use of the magnetic field produced by the magnets. The nonlinear vibration and electrical-output performances of the harvester at resonance are analyzed. The theoretical results indicate that the prototype can produce a load power of 7.619 mW, which is sufficient to supply low consumption wireless sensor nodes.

Swirling Flow of Magnetic Fluid in Multi-Pole Rotating Magnetic Field

2003 ◽  
Author(s):  
Kenichi Kamioka ◽  
Ryuichiro Yamane
Keyword(s):  
Magnetic Field ◽  
Fluid Flow ◽  
Circular Cylinder ◽  
Phase Velocity ◽  
Magnetic Fluid ◽  
Swirling Flow ◽  
Peak Velocity ◽  
Rotating Magnetic Field ◽  
Outer Periphery ◽  
The Magnetic Field

The experiments are conducted on the magnetic fluid flow induced by the multi-pole rotating magnetic field in a circular cylinder. The numbers of poles are two, four, six, eight and twelve. The applied electric current and frequency are 2∼6 A and 20∼60 Hz, respectively. The peak velocity of the flow increases with the increase in the strength and the phase velocity of the magnetic field. As the increase in the number of poles, the flow shifts to the outer periphery.

On Geometrical Invariants of the Magnetic Field Gradient Tensor in Turbulent Space Plasmas: Scale Variability in the Inertial Range

2019 ◽  
Vol 878 (2) ◽  
pp. 124 ◽  
Author(s):  
Virgilio Quattrociocchi ◽  
Giuseppe Consolini ◽  
Maria Federica Marcucci ◽  
Massimo Materassi
Keyword(s):  
Magnetic Field ◽  
Field Gradient ◽  
Magnetic Field Gradient ◽  
Inertial Range ◽  
Space Plasmas ◽  
Gradient Tensor ◽  
The Magnetic Field

scholarly journals Investigation of mixing time in liquid under influence of rotating magnetic field

2017 ◽  
Vol 38 (4) ◽  
pp. 555-565
Author(s):  
Alicja Przybył ◽  
Rafał Rakoczy ◽  
Maciej Konopacki ◽  
Marian Kordas ◽  
Radosław Drozd ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Experimental Investigation ◽  
Reynolds Number ◽  
Mixing Time ◽  
Rotating Magnetic Field ◽  
Homogenization Time ◽  
Set Up ◽  
The Relationship ◽  
The Magnetic Field

Abstract The aim of the study was to present an experimental investigation of the influence of the RMF on mixing time. The obtained results suggest that the homogenization time for the tested experimental set-up depending on the frequency of the RMF can be worked out by means of the relationship between the dimensionless mixing time number and the Reynolds number. It was shown that the magnetic field can be applied successfully to mixing liquids.

Effects of the magnetic field gradient on the wall power deposition of Hall thrusters

2017 ◽  
Vol 83 (2) ◽  
Author(s):  
Yongjie Ding ◽  
Peng Li ◽  
Xu Zhang ◽  
Liqiu Wei ◽  
Hezhi Sun ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Gradient ◽  
Discharge Channel ◽  
Magnetic Field Gradient ◽  
Zero Magnetic Field ◽  
Power Deposition ◽  
Neutral Gas ◽  
Channel Exit ◽  
Ionization Region ◽  
The Magnetic Field

The effect of the magnetic field gradient in the discharge channel of a Hall thruster on the ionization of the neutral gas and power deposition on the wall is studied through adopting the 2D-3V particle-in-cell (PIC) and Monte Carlo collisions (MCC) model. The research shows that by gradually increasing the magnetic field gradient while keeping the maximum magnetic intensity at the channel exit and the anode position unchanged, the ionization region moves towards the channel exit and then a second ionization region appears near the anode region. Meanwhile, power deposition on the walls decreases initially and then increases. To avoid power deposition on the walls produced by electrons and ions which are ionized in the second ionization region, the anode position is moved towards the channel exit as the magnetic field gradient is increased; when the anode position remains at the zero magnetic field position, power deposition on the walls decreases, which can effectively reduce the temperature and thermal load of the discharge channel.

Spin reorientation transition: phase diagrams and entropy change

2011 ◽  
Vol 1310 ◽  
Author(s):  
Vittorio Basso ◽  
Carlo P. Sasso ◽  
Michaela Kuepferling
Keyword(s):  
Magnetic Field ◽  
Easy Axis ◽  
Entropy Change ◽  
Rotating Magnetic Field ◽  
Spin Reorientation ◽  
Temperature Dependent ◽  
First Order ◽  
Crystalline Anisotropy ◽  
The Magnetic Field ◽  
Magneto Crystalline Anisotropy

ABSTRACTIn this paper we review the phase diagram and derive the entropy change for spin reorientation transitions by considering first order magnetization process theory with temperature dependent magneto-crystalline anisotropy constants. We derive the magnetic field-induced entropy change Δs for a transition between easy axis and easy plane, showing that for alternating magnetic field, Δs has a change of sign at the reorientation temperature, while for rotating magnetic field its sign is definite. We apply the model to CoZn W-type barium ferrite.

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