Permanent magnet assembly producing a strong tilted homogeneous magnetic field: towards magic angle field spinning NMR and MRI

Sakellariou, Dimitrios; Hugon, Cédric; Guiga, Angelo; Aubert, G.; Cazaux, S.; Hardy, P.

doi:10.1002/mrc.2683

Cited by 23 publications

(16 citation statements)

References 36 publications

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“…The idea here is to demonstrate that even if the coupling is time modulated, its averaged value is non zero and contributes to signal enhancement while adding supplementary modulation. This configuration might find uses in special experimental setups such as rheology NMR studies (43) or spinning NMR magnets (44) or even double rotation (DOR) as we will see later in this article.…”

Section: Other Coil Geometriesmentioning

confidence: 97%

NMR signal detection using inductive coupling: Applications to rotating microcoils

Jacquinot

Sakellariou

2011

Concepts Magnetic Resonance

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Sensitivity in solid-state nuclear magnetic resonance can be improved by the use of rotating microcoils (1). The connection to the rest of the electronics is performed through resonant inductive coupling. This mode of detection of nuclear induction has major advantages as it provides a wireless way to obtain extremely high radio-frequency amplitudes per unit current under sample rotation and thus improved sensitivity for size-limited samples. We review the circuit electronics and discuss experimental optimization of the probe and coil parameters. We also present alternative geometries for coupling between rotating coils and we explicitly calculate the signal enhancement. Two practical cases are presented, namely a standard magic angle sample spinning probe and a double sample rotation probe. We conclude with a theoretical discussion about the limits of detection attainable with coil miniaturization.

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Section: Other Coil Geometriesmentioning

confidence: 97%

NMR signal detection using inductive coupling: Applications to rotating microcoils

Jacquinot

Sakellariou

2011

Concepts Magnetic Resonance

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“…Most high performance assemblies use wedge-shaped magnet blocks, which require special magnet grinding and are best produced and assembled by experts. A few pseudo-Halbach dipole magnets for NMR have been built using clusters of identical permanent magnets that can be purchased, such as cylinders [6], cubes [12] and other regular prisms [21][22][23]. This last approach gave rise to the ''Mandhalas" family of magnets.…”

Section: Design Of Pseudo-halbach Arraysmentioning

confidence: 99%

“…The cylindrical structure and later the spherical structure [5] allowed dipolar magnetic fields exceeding 2 T to be produced. Since then, several research groups and companies have refined Halbach's structures and together with shim coils magnets up to around 1.5 T can be obtained with homogeneity to better than 0.05 ppm, allowing for the resolution of chemical shifts and nuclear spinspin couplings in the measured NMR spectra [6][7][8][9][10][11][12][13][14]. The sensitivity at 1.5 T is around 10 À7 1 H moles, sufficing for most analyses of solution-state samples in the synthetic chemistry laboratory and at a price point that can enter the teaching laboratory.…”

Section: Introductionmentioning

confidence: 99%

Low-cost, pseudo-Halbach dipole magnets for NMR

Tayler

Sakellariou

2017

Journal of Magnetic Resonance

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a b s t r a c tWe present designs for compact, inexpensive and strong dipole permanent magnets aimed primarily at magnetic resonance applications where prepolarization and detection occur at different locations. Lowhomogeneity magnets with a 7.5 mm bore size and field up to nearly 2 T are constructed using low-cost starting materials, standard workshop tools and only few hours of labor -an achievable project for a student or postdoc with spare time. As an application example we show how our magnet was used to polarize the nuclear spins in approximately 1 mL of pure [13 C]-methanol prior to detection of its highresolution NMR spectrum at zero field (measurement field below 10 À10 T), where signals appear at multiples of the carbon-hydrogen spin-spin coupling frequency 1 J CH ¼ 140:7ð1Þ Hz.

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“…However, it may be more practical to assemble cheaper and smaller arc-shaped magnets to obtain the same results produced by a single custom arc-shaped magnet as shown in Fig. 9(a) [27,28].…”

Section: Scaling Up the Magnetic Systems And Practicalmentioning

confidence: 99%

A Magnetically Actuated Drug Delivery System for Robotic Endoscopic Capsules

Munoz

Alici

2015

Journal of Medical Devices

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There is an increasing need to incorporate an actively controlled drug delivery system (DDS) into the next generation of capsule endoscopy in order to treat diseases in the gastrointestinal tract in a noninvasive way. Despite a number of attempts to magnetically actuate drug delivery mechanisms embedded in endoscopic capsules, longer operating distances and further miniaturization of on-board components are still drawbacks of such systems. In this paper, we propose an innovative magnetic system that consists of an array of magnets, which activates a DDS, based on an overly miniaturized slider-crank mechanism. We use analytical models to compare the magnetic fields generated by cylindrical and arc-shaped magnets. Our experimental results, which are in agreement with the analytical results, show that an optimally configured array of the magnets enhances the magnetic field and also the driving magnetic torque and subsequently, it imposes a high enough force on the piston of the DDS to expel a required dose of a drug out of a reservoir. We conclude that the proposed magnetic field optimization method is effective in establishing an active DDS that is designed to deliver drug profiles with accurate control of the release rate, release amount, and number of doses. There is an increasing need to incorporate an actively controlled drug delivery system (DDS) into the next generation of capsule endoscopy in order to treat diseases in the gastrointestinal tract in a noninvasive way. Despite a number of attempts to magnetically actuate drug delivery mechanisms embedded in endoscopic capsules, longer operating distances and further miniaturization of on-board components are still drawbacks of such systems. In this paper, we propose an innovative magnetic system that consists of an array of magnets, which activates a DDS, based on an overly miniaturized slider-crank mechanism. We use analytical models to compare the magnetic fields generated by cylindrical and arc-shaped magnets. Our experimental results, which are in agreement with the analytical results, show that an optimally configured array of the magnets enhances the magnetic field and also the driving magnetic torque and subsequently, it imposes a high enough force on the piston of the DDS to expel a required dose of a drug out of a reservoir. We conclude that the proposed magnetic field optimization method is effective in establishing an active DDS that is designed to deliver drug profiles with accurate control of the release rate, release amount, and number of doses.

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Permanent magnet assembly producing a strong tilted homogeneous magnetic field: towards magic angle field spinning NMR and MRI

Cited by 23 publications

References 36 publications

NMR signal detection using inductive coupling: Applications to rotating microcoils

NMR signal detection using inductive coupling: Applications to rotating microcoils

Low-cost, pseudo-Halbach dipole magnets for NMR

A Magnetically Actuated Drug Delivery System for Robotic Endoscopic Capsules

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