An analytical methodology for magnetic field control in unilateral NMR

Marble, Andrew E.; Mastikhin, Igor V.; Colpitts, Bruce G.; Balcom, Bruce J.

doi:10.1016/j.jmr.2005.01.009

Cited by 55 publications

(43 citation statements)

References 22 publications

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“…Another class of unilateral NMR instrument has been developed by Marble et al [22,27]. In these sensors, the unilateral magnet array consisted of three block magnets all magnetized along the same directions, see Fig.…”

Section: Portable Single-sided Nmr Sensors With Open Geometrymentioning

confidence: 99%

“…In this work, a novel design of unilateral NMR instrument with larger measurement volume and higher signal to noise ratio [22,27] has allowed to reduce the time measurement of the fat content in packaged dairy products about up to few seconds. Two methods were tested: a diffusion-edited CPMG technique and a strongly T 1 -weighted conventional CPMG method requiring total measurement times of about 39 and 7 s, respectively.…”

Section: Application Of Single-sided Nmr Sensors To Food Matricesmentioning

confidence: 99%

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Portable NMR in food analysis

Capitani

Sobolev

Tullio

et al. 2017

Chem. Biol. Technol. Agric.

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Low-field 1 H NMR relaxometry is an important tool used to investigate on the most abundant components of intact foodstuffs based on relaxation parameters and amplitude of the NMR signals. In particular, information on water compartments, diffusion and movement can be obtained by detecting proton signals prevalently ascribable to H 2 O contained in foodstuffs. The main advantage of this technique is that it does not require any pretreatment of the sample and once developed, standard protocols based on rapid measurements can be easily transferred to quality control applications. An actual breakthrough for the low-field NMR application to food science has certainly been the development of unilateral NMR sensors. These devices present an attractive option for non-invasive assessment of compositional and microstructure of food materials. They are portable and allow easy sample access, which makes them attractive for quality control in industrial environments and directly on sealed packaged foods. A price to pay is the inhomogeneity of the magnetic field, which compromises the sensitivity of these devices. However, recent developments in unilateral magnets design offer larger sensitive volume, higher sensitivity and shorter dead times. In this brief review, we highlight the different uses of unilateral NMR devices in food analysis.

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Section: Portable Single-sided Nmr Sensors With Open Geometrymentioning

confidence: 99%

Section: Application Of Single-sided Nmr Sensors To Food Matricesmentioning

confidence: 99%

Portable NMR in food analysis

Capitani

Sobolev

Tullio

et al. 2017

Chem. Biol. Technol. Agric.

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show abstract

“…Other systems used for profiling outside a magnet array have shaped pole pieces (2,16). The singlesided magnets in Fig.…”

Section: Compact Magnets For Magnetic Resonance 53mentioning

confidence: 99%

Compact magnets for magnetic resonance

Demas

Prado

2009

Concepts Magnetic Resonance

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“…Here, (4) must be optimized under the equality constraints, (8), where each is a positive scalar fixing a rod's magnitude and the n x n matrices Kj are symmetric and positive definite where n is the number of basis fields (8) In our application, has the diagonal elements corresponding to the jth rod's x and y dipole fields set to 1 with the remaining elements set to 0.…”

Section: Constraintsmentioning

confidence: 99%

“…We approximate optimal coefficients, (10), by substitution into the constraints, (8), to first order in .…”

Section: Constraintsmentioning

confidence: 99%

Least Squares Magnetic-Field Optimization for Portable Nuclear Magnetic Resonance Magnet Design

et al. 2008

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Single-sided and mobile nuclear magnetic resonance (NMR) sensors have the advantages of portability, low cost, and low power consumption compared to conventional high-field NMR and magnetic resonance imaging (MRI) systems. We present fast, flexible, and easy-to-implement target field algorithms for mobile NMR and MRI magnet design. The optimization finds a global optimum in a cost function that minimizes the error in the target magnetic field in the sense of least squares.When the technique is tested on a ring array of permanent-magnet elements, the solution matches the classical dipole Halbach solution. For a single-sided handheld NMR sensor, the algorithm yields a 640 G field homogeneous to 16 100 ppm across a 1.9 cm 3 volume located 1.5 cm above the top of the magnets and homogeneous to 32 200 ppm over a 7.6 cm 3 volume. This regime is adequate for MRI applications. We demonstrate that the homogeneous region can be continuously moved away from the sensor by rotating magnet rod elements, opening the way for NMR sensors with adjustable "sensitive volumes."

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An analytical methodology for magnetic field control in unilateral NMR

Cited by 55 publications

References 22 publications

Portable NMR in food analysis

Portable NMR in food analysis

Compact magnets for magnetic resonance

Least Squares Magnetic-Field Optimization for Portable Nuclear Magnetic Resonance Magnet Design

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