Magnetic Nanoparticle Based Nanofluid Actuation With Dynamic Magnetic Fields

2011 ◽  
Author(s):  
Alp Bilgin ◽  
Evrim Kurtoglu ◽  
Hadi Cagdas Erk ◽  
Muhsincan Sesen ◽  
Havva Funda Yagci Acar ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Nanoparticle ◽  
Magnetic Actuation ◽  
Flow Properties ◽  
Pumping System ◽  
Magnetically Actuated ◽  
Microscale Flow ◽  
Nanoparticle Suspensions ◽  
Alternative Research

Magnetic nanoparticle suspensions and their manipulation are becoming an alternative research line and have very important applications in the field of microfluidics such as microscale flow control in microfluidic circuits, actuation of fluids in microscale, and drug delivery mechanisms. In microscale, it is possible and beneficial to use magnetic fields as actuators of such nanofluids, where these fluids could move along a gradient of magnetic field so that a micropump without any moving parts could be generated with this technique. Thus, magnetically actuated nanofluids could have the potential to be used as an alternative micro pumping system. Actuation of ferrofluid plugs with a changing magnetic field has been extensively studied in the literature. However; the flow properties of ferrofluids are sparsely investigated when the ferrofluid itself is forced to continuously flow inside a channel. As an extension of previous studies, this study aims to investigate flows of magnetic nanoparticle based nanofluids by a generated magnetic field and to compare the efficiency of the resulting system. Lauric Acid coated Super Paramagnetic Iron Oxide (SPIO-LA) was used as the ferrofluid sample in the experiments to realise actuation. Significant flow rates up to 61.8μL/s at nominal maximum magnetic field strengths of 300mT were achieved in the experiments. Results suggest that nanofluids with magnetic nanoparticles merit more research efforts in micro pumping. Thus, magnetic actuation could be a significant alternative for more common techniques such as electromechanical, electrokinetic, and piezoelectric actuation.

scholarly journals Enhanced real-time pose estimation for closed-loop robotic manipulation of magnetically actuated capsule endoscopes

2018 ◽  
Vol 37 (8) ◽  
pp. 890-911 ◽  
Author(s):  
Addisu Z Taddese ◽  
Piotr R Slawinski ◽  
Marco Pirotta ◽  
Elena De Momi ◽  
Keith L Obstein ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Pose Estimation ◽  
Closed Loop ◽  
Estimation Methods ◽  
Closed Loop Control ◽  
Point Dipole ◽  
Magnetic Actuation ◽  
Loop Control ◽  
Magnetically Actuated ◽  
Capsule Endoscopes

Pose estimation methods for robotically guided magnetic actuation of capsule endoscopes have recently enabled trajectory following and automation of repetitive endoscopic maneuvers. However, these methods face significant challenges in their path to clinical adoption including the presence of regions of magnetic field singularity, where the accuracy of the system degrades, and the need for accurate initialization of the capsule’s pose. In particular, the singularity problem exists for any pose estimation method that utilizes a single source of magnetic field if the method does not rely on the motion of the magnet to obtain multiple measurements from different vantage points. We analyze the workspace of such pose estimation methods with the use of the point-dipole magnetic field model and show that singular regions exist in areas where the capsule is nominally located during magnetic actuation. As the dipole model can approximate most magnetic field sources, the problem discussed herein pertains to a wider set of pose estimation techniques. We then propose a novel hybrid approach employing static and time-varying magnetic field sources and show that this system has no regions of singularity. The proposed system was experimentally validated for accuracy, workspace size, update rate, and performance in regions of magnetic singularity. The system performed as well or better than prior pose estimation methods without requiring accurate initialization and was robust to magnetic singularity. Experimental demonstration of closed-loop control of a tethered magnetic device utilizing the developed pose estimation technique is provided to ascertain its suitability for robotically guided capsule endoscopy. Hence, advances in closed-loop control and intelligent automation of magnetically actuated capsule endoscopes can be further pursued toward clinical realization by employing this pose estimation system.

Tuning mass transport in magnetic nanoparticle-filled viscoelastic hydrogels using low-frequency rotating magnetic fields

Soft Matter ◽  
2017 ◽  
Vol 13 (36) ◽  
pp. 6259-6269 ◽  
Author(s):  
Shahab Boroun ◽  
Faïçal Larachi
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Mass Transport ◽  
Magnetic Nanoparticle ◽  
Low Frequency ◽  
Rotating Magnetic Field ◽  
Rotating Magnetic Fields ◽  
Rotational Movement

Rotational movement of MNPs in ferrogels in an external rotating magnetic field for tuning mass transport.

Magnetic field induced concentration gradients in magnetic nanoparticle suspensions: Theory and experiment

2008 ◽  
Vol 103 (6) ◽  
pp. 063916 ◽  
Author(s):  
Randall M. Erb ◽  
David S. Sebba ◽  
Anne A. Lazarides ◽  
Benjamin B. Yellen
Keyword(s):  
Magnetic Field ◽  
Magnetic Nanoparticle ◽  
Concentration Gradients ◽  
Nanoparticle Suspensions ◽  
Theory And Experiment

Behaviors of Bio-Functionalized Magnetic Nanoparticle Clusters in a Rotating Magnetic Field

2012 ◽  
Author(s):  
Chin-Yih Hong ◽  
Ji-Ching Lai ◽  
Chia-Chung Tang
Keyword(s):  
Magnetic Field ◽  
Aqueous Solution ◽  
Magnetic Nanoparticles ◽  
Magnetic Fields ◽  
Magnetic Nanoparticle ◽  
Critical Diameter ◽  
Rotating Magnetic Field ◽  
Magnetic Clusters ◽  
Rotating Magnetic Fields ◽  
Nanoparticle Clusters

Manipulation of magnetic nanoparticles has many applications in several fields and the behaviors of magnetic nanoparticles subjected to rotating or alternating magnetic fields attracted more attention from biomedical applications. In an aqueous solution containing bio-functionalized magnetic nanoparticles, due to the interaction between biomolecules, these nanoparticles agglomerate and form clusters with various sizes and shapes. In this study, the behaviors of magnetic nanoparticle clusters in an aqueous solution under rotating magnetic fields were investigated. Due to the interaction between the rotating magnetic field and the net magnetic dipole moment, the clusters were subjected to forced vibration. Two motion modes of clusters were observed as the magnetic field rotated. These two modes are rotation and oscillation. The diameters of the magnetic clusters with rotational or oscillational motions were measured. A critical diameter range of magnetic cluster was defined and the range is between 10.21 μm and 6.17 μm that could be used to distinguish rotation and oscillation of clusters.

Calculated Coronal Magnetic Fields and Their Comparison with the Coronal Structures as Observed during Five Solar Eclipses

1994 ◽  
Vol 144 ◽  
pp. 559-564
Author(s):  
P. Ambrož ◽  
J. Sýkora
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Magnetic Fields ◽  
Solar Corona ◽  
Coronal Magnetic Field ◽  
Coronal Magnetic Fields ◽  
Solar Eclipses ◽  
Coronal Structures

AbstractWe were successful in observing the solar corona during five solar eclipses (1973-1991). For the eclipse days the coronal magnetic field was calculated by extrapolation from the photosphere. Comparison of the observed and calculated coronal structures is carried out and some peculiarities of this comparison, related to the different phases of the solar cycle, are presented.

Radio Measurements of Coronal Magnetic Fields

1994 ◽  
Vol 144 ◽  
pp. 21-28 ◽  
Author(s):  
G. B. Gelfreikh
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Solar Corona ◽  
Active Regions ◽  
High Sensitivity ◽  
Coronal Magnetic Field ◽  
Transverse Magnetic ◽  
Radio Sources ◽  
Radio Waves ◽  
Solar Active Regions

AbstractA review of methods of measuring magnetic fields in the solar corona using spectral-polarization observations at microwaves with high spatial resolution is presented. The methods are based on the theory of thermal bremsstrahlung, thermal cyclotron emission, propagation of radio waves in quasi-transverse magnetic field and Faraday rotation of the plane of polarization. The most explicit program of measurements of magnetic fields in the atmosphere of solar active regions has been carried out using radio observations performed on the large reflector radio telescope of the Russian Academy of Sciences — RATAN-600. This proved possible due to good wavelength coverage, multichannel spectrographs observations and high sensitivity to polarization of the instrument. Besides direct measurements of the strength of the magnetic fields in some cases the peculiar parameters of radio sources, such as very steep spectra and high brightness temperatures provide some information on a very complicated local structure of the coronal magnetic field. Of special interest are the results found from combined RATAN-600 and large antennas of aperture synthesis (VLA and WSRT), the latter giving more detailed information on twodimensional structure of radio sources. The bulk of the data obtained allows us to investigate themagnetospheresof the solar active regions as the space in the solar corona where the structures and physical processes are controlled both by the photospheric/underphotospheric currents and surrounding “quiet” corona.

Emergence of Twisted Magnetic Flux Related Sigmoidal Brightening

2000 ◽  
Vol 179 ◽  
pp. 263-264
Author(s):  
K. Sundara Raman ◽  
K. B. Ramesh ◽  
R. Selvendran ◽  
P. S. M. Aleem ◽  
K. M. Hiremath
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Ultra Violet ◽  
Active Regions ◽  
Morphological Properties ◽  
Energy Storage And Conversion ◽  
The Sun ◽  
X Rays ◽  
The Magnetic Field

Extended AbstractWe have examined the morphological properties of a sigmoid associated with an SXR (soft X-ray) flare. The sigmoid is cospatial with the EUV (extreme ultra violet) images and in the optical part lies along an S-shaped Hαfilament. The photoheliogram shows flux emergence within an existingδtype sunspot which has caused the rotation of the umbrae giving rise to the sigmoidal brightening.It is now widely accepted that flares derive their energy from the magnetic fields of the active regions and coronal levels are considered to be the flare sites. But still a satisfactory understanding of the flare processes has not been achieved because of the difficulties encountered to predict and estimate the probability of flare eruptions. The convection flows and vortices below the photosphere transport and concentrate magnetic field, which subsequently appear as active regions in the photosphere (Rust & Kumar 1994 and the references therein). Successive emergence of magnetic flux, twist the field, creating flare productive magnetic shear and has been studied by many authors (Sundara Ramanet al.1998 and the references therein). Hence, it is considered that the flare is powered by the energy stored in the twisted magnetic flux tubes (Kurokawa 1996 and the references therein). Rust & Kumar (1996) named the S-shaped bright coronal loops that appear in soft X-rays as ‘Sigmoids’ and concluded that this S-shaped distortion is due to the twist developed in the magnetic field lines. These transient sigmoidal features tell a great deal about unstable coronal magnetic fields, as these regions are more likely to be eruptive (Canfieldet al.1999). As the magnetic fields of the active regions are deep rooted in the Sun, the twist developed in the subphotospheric flux tube penetrates the photosphere and extends in to the corona. Thus, it is essentially favourable for the subphotospheric twist to unwind the twist and transmit it through the photosphere to the corona. Therefore, it becomes essential to make complete observational descriptions of a flare from the magnetic field changes that are taking place in different atmospheric levels of the Sun, to pin down the energy storage and conversion process that trigger the flare phenomena.

Peculiarity Parameters

1976 ◽  
Vol 32 ◽  
pp. 233-254
Author(s):  
H. M. Maitzen
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Theoretical Work ◽  
Observational Evidence ◽  
Rotator Model ◽  
Peculiar Behaviour ◽  
Field Spectrum ◽  
Oblique Rotator ◽  
Ap Stars ◽  
The Way

Ap stars are peculiar in many aspects. During this century astronomers have been trying to collect data about these and have found a confusing variety of peculiar behaviour even from star to star that Struve stated in 1942 that at least we know that these phenomena are not supernatural. A real push to start deeper theoretical work on Ap stars was given by an additional observational evidence, namely the discovery of magnetic fields on these stars by Babcock (1947). This originated the concept that magnetic fields are the cause for spectroscopic and photometric peculiarities. Great leaps for the astronomical mankind were the Oblique Rotator model by Stibbs (1950) and Deutsch (1954), which by the way provided mathematical tools for the later handling pulsar geometries, anti the discovery of phase coincidence of the extrema of magnetic field, spectrum and photometric variations (e.g. Jarzebowski, 1960).

Nuclear magnetic resonance microscopy

1989 ◽  
Vol 47 ◽  
pp. 828-829
Author(s):  
Paul C. Lauterbur
Keyword(s):  
Magnetic Field ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Fields ◽  
Signal To Noise ◽  
Field Gradients ◽  
Useful Signal ◽  
Magnetic Field Gradients ◽  
Observation Times ◽  
Nuclear Magnetic

Nuclear magnetic resonance imaging can reach microscopic resolution, as was noted many years ago, but the first serious attempt to explore the limits of the possibilities was made by Hedges. Resolution is ultimately limited under most circumstances by the signal-to-noise ratio, which is greater for small radio receiver coils, high magnetic fields and long observation times. The strongest signals in biological applications are obtained from water protons; for the usual magnetic fields used in NMR experiments (2-14 tesla), receiver coils of one to several millimeters in diameter, and observation times of a number of minutes, the volume resolution will be limited to a few hundred or thousand cubic micrometers. The proportions of voxels may be freely chosen within wide limits by varying the details of the imaging procedure. For isotropic resolution, therefore, objects of the order of (10μm) may be distinguished.Because the spatial coordinates are encoded by magnetic field gradients, the NMR resonance frequency differences, which determine the potential spatial resolution, may be made very large. As noted above, however, the corresponding volumes may become too small to give useful signal-to-noise ratios. In the presence of magnetic field gradients there will also be a loss of signal strength and resolution because molecular diffusion causes the coherence of the NMR signal to decay more rapidly than it otherwise would. This phenomenon is especially important in microscopic imaging.

Germination and initial growth of triticale seeds under stationary magnetic fields

2014 ◽  
Vol 2 (2) ◽  
pp. 72-79 ◽  
Author(s):  
Mercedes Florez ◽  
Elvira Martinez ◽  
Victoria Carbonell
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Seed Vigor ◽  
Initial Growth ◽  
Practical Application ◽  
Biochemical Processes ◽  
Mean Germination Time ◽  
Nutrition Value ◽  
The Mean ◽  
Growth Of Seedlings

The main objective of this study is to determine the effects of 125 mT and 250mT magnetic treatment on the germination and initial growth of triticale seeds. This objective has a practical application in agriculture science: early growth of triticale. An increase in the percentage and rate of germination of seeds and a stimulation of growth of seedlings as positive response to magnetic field treatment in rice, wheat, maize and barley seeds have been found in previous studies. Germination tests were carried out under laboratory conditions by exposing triticale seeds to magnetic field for different times. The effect was studied by exposure of seeds prior sowing. The mean germination time were reduced for all the magnetic treatments applied. Most significant differences were obtained for time of exposure of 1 and 24 hours and maximum reductions was 12%. Furthermore, seedlings from magnetically treated seeds grew taller than control. The longest mean total length was obtained from seedlings exposed to 125 and 250 mT for 24 hours. External magnetic fields are assumed to enhance seed vigor by influencing the biochemical processes by stimulating activity of proteins and enzymes. Numerous studies suggested that magnetic field increases ions uptake and consequently improves nutrition value.

Sign in / Sign up

Export Citation Format

Share Document