A low-field, low-cost Halbach magnet array for open-access NMR
B.P. Hills, K.M. Wright and D.G. Gillies
Journal of Magnetic Resonance
Volume 175, Issue 2, August 2005, Pages 336-339
DOI: 10.1016/j.jmr.2005.04.015
Abstract
A working prototype of a novel low-cost Halbach-array-based NMR system is described. The new design provides open access to the sample relative to conventional NMR magnet designs and this facilitates the simultaneous use of multi-sensor techniques on the same sample, in which NMR/MRI can potentially be combined with other spectroscopies such as impedance spectroscopy, laser scattering and rheological experiments.
Table Top Micro Fluidic Nuclear Magnetic Resonance Spectrometer
James Stephenson and Cynthia Furse
University of Utah
[Looks like a Thesis, or the first part of a major work:<"ursi-test.intec.ugent.be/files/URSIGA08/papers/K02ap6.pdf" (5 February, 2010)>]
Abstract
Nuclear Magnetic Resonance (NMR) spectroscopy is a powerful tool used to analyze the physical and chemical structure of macro/microscopic molecules for a large variety of applications. As an analytical tool NMR is prohibitively expensive for most laboratories, limiting its use in academics and field research. Additionally, an NMR spectrometer is generally very large, approximately one thousand cubic feet, and requires substantial support services such as a computer system and the liquid nitrogen used to support the cryogenically cooled electromagnet. This paper describes the methodologies involved in the development of a field portable NMR technology based on rare earth permanent magnets and fabrication techniques derived from Micro Electro Mechanical Systems (MEMS) technology. The fabrication of microscale helical antennas surrounding an integrated capillary for the analysis of biological fluids (blood, urine, tears, amniotic fluid, saliva, etc.) and chemical agent sensing for homeland security is also detailed. The motivating factors for down-scaling the components of an NMR spectrometer include improvements to the signal to noise ratio, vastly smaller sample volume requirements and reduced dependence on high performance superconducting electromagnets. The technology described here may enable a small, portable, inexpensive NMR capable of being used in-line for water or chemical analysis or as a diagnostic tool in medical offices. The major novel components of this system are the permanent magnetic with very high yet uniform localized field strength and a 100% fill factor coil for
improved SNR.
A Comparison of Induction-Detection NMR and Force-Detection NMR on Micro-NMR Device Design
Wen-Chieh Lin and Gary K. Fedder
Also looks like a thesis or a report: The Robotics Institute, School of Computer Science, Carnegie Mellon University <"www.cs.cmu.edu/~wclin/nmr/micro-NMR2.pdf" (5 February, 2010)>
Abstract
Nuclear Magnetic Resonance (NMR) is widely used in medical diagnostics and chemical analysis. Due to rapid growing of the NMR applications, the conventional NMR systems may not fulfill the need of all applications. The development of a micro-NMR device would not only benefit the original NMR applications but could also open a door for new NMR applications. Two approaches for building a NMR system, Induction-Detection Nuclear Magnetic Resonance (IDNMR) and Force-Detection Nuclear Magnetic Resonance (FDNMR) are explored and compared in this paper. The comparison result shows that the FDNMR approach outperforms the IDNMR approach in signal-to-noise ratio when the sample radius is below 410 mm for protons and 1900 mm for chlorides. This suggests that the FDNMR approach is more appropriate for making the micro-NMR
device.
Design, construction and NMR testing of a 1 Tesla Halbach Permanent Magnet for Magnetic Resonance
Xiaofeng Zhang, Venu Mahesh, David Ng, Ryan Hubbard, Amit Ailiani, Bernie O’Hare, Alan Benesi and Andrew Webb.
Excerpt from the Proceedings of the COMSOL Users Conference 2005 Boston <"cds.comsol.com/access/dl/papers/1469/Webb.pdf" (5 February, 2010)>
Abstract
Widespread use of magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) spectroscopy in research, industry, and education is limited by the physical size and the very high procurement and maintainance costs of a superconducting magnet. Attempts have been made to replace the superconducting magnet with a permanent magnet. However, the reported permanent magnets have typically been limited to very low field strengths, or very small useable volumes. In this paper, we introduce a design of a portable table-top magnet with a field strength of 1 tesla (i.e., a 1H resonance frequency of 42.5 MHz), which consists of an array of 36 cylindrical permanent magnet rods positioned to achieve a reasonably homogeneous magnetic field within an extended region. Threedimensional (3D) numerical magnetostatic simulations were performed using FEMLAB. The simulated results of the magnetic flux density, frequently referred to as the “B0 field” in the MRI and NMR community, were compared with the measurements obtained using a digital teslameter. The simulated and measured B0 field were found to be very similar. The initial utility of the permanent magnet has been demonstrated by the acquisition of NMR spectra using a custom-built microcoil probe.
A Force-Detection NMR Sensor in CMOS-MEMS
Kevin M. Frederick
Masters Thesis, Carnegie Mellon University, Pittsburgh, Pennsylvania <"www.ece.cmu.edu/~mems/pubs/pdfs/ece/ms.../0090_frederick-2003.pdf" (5 February, 2010)>
Abstract
Nuclear Magnetic Resonance (NMR) on micro-liter samples using the Force Detection NMR (FDNMR) method will enable mobile and embedded detection of many elements without a multi-tesla superconducting magnet. This report presents a FDNMR sensor which has the ability to detect hydrogen of a
0.52 mL water sample in a 1 tesla magnetic field. The sensor is a micromachined cantilevered paddle within a CMOS chip measuring 2.5 mm x 2.5 mm x 540 mm with integrated amplification electronics.
To begin the paddle fabrication, a 30 mm thick silicon membrane with a thin layer of CMOS interconnect on top, is made by Deep Reactive Ion Etching (DRIE) the backside of the chip. The backside area is patterned with photoresist and etched into many close-proximity, slightly undercut high-aspect-ratio trenches to achieve a uniform membrane thickness. The resulting membrane measures 1370 mm by 1850 mm, with center to edge thickness variations less than 5 mm. A 0.6 mm x 0.6 mm x 0.25 mm piece of pure nickel is glued to the etched membrane surface as a detector magnet. Freon plasma etches trenches into the silicon dioxide interconnect layer not masked by aluminum, and a final DRIE extends the trenches through the silicon membrane. The final etch releases the folded-mass cantilever with 1 mm long spring beams and a 1.1 mm2 paddle surrounded by a capacitive bridge sensor to measure vertical displacement.
Integrated electronics drive the input and amplify the output of he balanced capacitive bridge which is made of lateral air gap capacitors between interdigitated micromechanical fingers. Force induced vertical cantilever displacement imbalances the bridge and the amplified output signal is measured by external test equipment. The bridge has the dynamic range to measure up to ±0.5 mm displacement at the maximum sensitivity of 5.12 mV/nm and up to ±2.0 mm with less sensitivity.
The FDNMR sensor is tested in response to electrostatic, mechanical, acceleration, and magnetic forces. The cantilevered paddle at 760 Torr resonates at 3.6 kHz (Q = 20) compared to 3.0 kHz (Q = 430) by simulation. The bridge output amplitude is linear with oscillating magnetic force amplitude. Estimated noise bandwidth is extracted from time-domain averaging of experimental data. Assuming a 1 MHz system bandwidth, 512 measurements equal a 1.95 kHz noise bandwidth and a 2.4 Å displacement noise floor with an SNR of 1. This displacement corresponds to a 4.4 pN oscillating force at 2.5 mTorr. A 100 Hz noise bandwidth will detect the 1.0 pN FDNMR force from a 0.52 mL water sample in a 1 tesla magnetic field.
Single-Sided NMR with a Halbach Magnet
Wei-Hao Chang, Jyh-Homg Chen and Lian-Pin Whang
Magnetic Resonance Imaging
2006, vol. 24(
pp. 1095-1102
INIST-CNRS, Cote INIST : 19716, 35400014529870.0140
Abstract
A single-sided mobile NMR apparatus with a small Halbach magnet was constructed for the first time. It is lightweight, compact and exhibits good sensitivity. The weight of the device is only 2 kg, and the NMR signal of the pencil eraser block can be detected in one shot using the device. This study describes the characteristics of this instrument, including the profile of static magnetic flux density, B0, the sensitivity in the depth direction and its effectiveness in one-dimensional profiling. Its usefulness in differentiating soft materials and evaluating the extent of damage of a material is demonstrated based on T2 relaxation data. The moisture absorbance also can be observed
from the increase of the echo amplitude of the NMR spin echo signal.
Development of Halbach Magnet for Portable NMR device
N. Dogan1, R. Topkaya, H. Subas?, Y.Yerli, B.Rameev
Journal of Physics: Conference Series
153 (2009) 012047
doi:10.1088/1742-6596/153/1/012047
Abstract
Nuclear magnetic resonance (NMR) has enormous potential for various applications in industry as the on-line or at-line test/control device of process environments. Advantage of NMR is its non-destructive nature, because it does not require the measurement probe to have a contact with the tested media. Despite of the recent progress in this direction, application of NMR in industry is still very limited. This is related to the technical and analytical complications of NMR as a method, and high cost of NMR analyzers available at the market. However in many applications, NMR is a very useful technique to test various products and to monitor quantitatively industrial processes. Fortunately usually there is no need in a high-field superconducting magnets to obtain the high-resolution spectra with the detailed information on chemical shifts and coupling-constant. NMR analyzers are designed to obtain the relaxation parameters by measuring the NMR spectra in the time domain rather than in frequency domain. Therefore it is possible to use small magnetic field (and low frequency of 2-60 MHz) in NMR systems, based on permanent magnet technology, which are specially designed for specific at-line and on-line process applications. In this work we present the permanent magnet system developed to use in the portative NMR devices. We discuss the experimental parameters of the designed Halbach magnet system and compare them with results of theoretical modelling.
Design and Analysis of the Novel Test Tube Magnet for Portable NMR Device
Jizhong Chen, Yiming Zhang, and Jijun Xiao
IEEE Transactions on Magnetics
Volume: 43(9) Part 1 2007, 3555-3557
DOI:10.2529/PIERS060907042202
Abstract
The paper presents a novel test tube magnet (TTM) for Portable NMR device, which is composed of a dipole cylinder magnet and a hemi-cylinder or a hemi-sphere magnet. The hemi-cylinder or the hemi-sphere magnet is attached to one end of the dipole cylinder magnet, so that the whole magnet is shaped like a test tube. TTM generates a wide diameter spherical volume (DSV) with a high magnetic field homogeneity, which makes the device more applicable for portable NMR. The two configurations were simulated with three-dimensional finite-element methods. Flux density elements are effectively corrected in the DSV. The homogeneity increases, the magnet volumes and mass are markedly decreased, and the construction is very reasonable. Taken together the new designs have improved characteristics for portable NMR.
Permanent Magnets for Production and Use of High Energy Particle Beams
Klaus Halbach
8th Intern. Workshop on Rare Earth Magnets and their Appl., Dayton, Ohio, 6 May 1985
LBL-19285; CONF-850534-1
OSTI ID: 5844976; Legacy ID: DE85009934
Abstract
In the last few years, permanent magnet systems have begun to play a dominant role in the generation of synchrotron radiation and the operation of free electron lasers. Similarly, permanent magnets can lead to significant improvements of accelerators and systems that use them. The general conditions are discussed under which one can expect benefits from permanent magnets, and a number of specific applications will be described in detail.
B.P. Hills, K.M. Wright and D.G. Gillies
Journal of Magnetic Resonance
Volume 175, Issue 2, August 2005, Pages 336-339
DOI: 10.1016/j.jmr.2005.04.015
Abstract
A working prototype of a novel low-cost Halbach-array-based NMR system is described. The new design provides open access to the sample relative to conventional NMR magnet designs and this facilitates the simultaneous use of multi-sensor techniques on the same sample, in which NMR/MRI can potentially be combined with other spectroscopies such as impedance spectroscopy, laser scattering and rheological experiments.
Table Top Micro Fluidic Nuclear Magnetic Resonance Spectrometer
James Stephenson and Cynthia Furse
University of Utah
[Looks like a Thesis, or the first part of a major work:<"ursi-test.intec.ugent.be/files/URSIGA08/papers/K02ap6.pdf" (5 February, 2010)>]
Abstract
Nuclear Magnetic Resonance (NMR) spectroscopy is a powerful tool used to analyze the physical and chemical structure of macro/microscopic molecules for a large variety of applications. As an analytical tool NMR is prohibitively expensive for most laboratories, limiting its use in academics and field research. Additionally, an NMR spectrometer is generally very large, approximately one thousand cubic feet, and requires substantial support services such as a computer system and the liquid nitrogen used to support the cryogenically cooled electromagnet. This paper describes the methodologies involved in the development of a field portable NMR technology based on rare earth permanent magnets and fabrication techniques derived from Micro Electro Mechanical Systems (MEMS) technology. The fabrication of microscale helical antennas surrounding an integrated capillary for the analysis of biological fluids (blood, urine, tears, amniotic fluid, saliva, etc.) and chemical agent sensing for homeland security is also detailed. The motivating factors for down-scaling the components of an NMR spectrometer include improvements to the signal to noise ratio, vastly smaller sample volume requirements and reduced dependence on high performance superconducting electromagnets. The technology described here may enable a small, portable, inexpensive NMR capable of being used in-line for water or chemical analysis or as a diagnostic tool in medical offices. The major novel components of this system are the permanent magnetic with very high yet uniform localized field strength and a 100% fill factor coil for
improved SNR.
A Comparison of Induction-Detection NMR and Force-Detection NMR on Micro-NMR Device Design
Wen-Chieh Lin and Gary K. Fedder
Also looks like a thesis or a report: The Robotics Institute, School of Computer Science, Carnegie Mellon University <"www.cs.cmu.edu/~wclin/nmr/micro-NMR2.pdf" (5 February, 2010)>
Abstract
Nuclear Magnetic Resonance (NMR) is widely used in medical diagnostics and chemical analysis. Due to rapid growing of the NMR applications, the conventional NMR systems may not fulfill the need of all applications. The development of a micro-NMR device would not only benefit the original NMR applications but could also open a door for new NMR applications. Two approaches for building a NMR system, Induction-Detection Nuclear Magnetic Resonance (IDNMR) and Force-Detection Nuclear Magnetic Resonance (FDNMR) are explored and compared in this paper. The comparison result shows that the FDNMR approach outperforms the IDNMR approach in signal-to-noise ratio when the sample radius is below 410 mm for protons and 1900 mm for chlorides. This suggests that the FDNMR approach is more appropriate for making the micro-NMR
device.
Design, construction and NMR testing of a 1 Tesla Halbach Permanent Magnet for Magnetic Resonance
Xiaofeng Zhang, Venu Mahesh, David Ng, Ryan Hubbard, Amit Ailiani, Bernie O’Hare, Alan Benesi and Andrew Webb.
Excerpt from the Proceedings of the COMSOL Users Conference 2005 Boston <"cds.comsol.com/access/dl/papers/1469/Webb.pdf" (5 February, 2010)>
Abstract
Widespread use of magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) spectroscopy in research, industry, and education is limited by the physical size and the very high procurement and maintainance costs of a superconducting magnet. Attempts have been made to replace the superconducting magnet with a permanent magnet. However, the reported permanent magnets have typically been limited to very low field strengths, or very small useable volumes. In this paper, we introduce a design of a portable table-top magnet with a field strength of 1 tesla (i.e., a 1H resonance frequency of 42.5 MHz), which consists of an array of 36 cylindrical permanent magnet rods positioned to achieve a reasonably homogeneous magnetic field within an extended region. Threedimensional (3D) numerical magnetostatic simulations were performed using FEMLAB. The simulated results of the magnetic flux density, frequently referred to as the “B0 field” in the MRI and NMR community, were compared with the measurements obtained using a digital teslameter. The simulated and measured B0 field were found to be very similar. The initial utility of the permanent magnet has been demonstrated by the acquisition of NMR spectra using a custom-built microcoil probe.
A Force-Detection NMR Sensor in CMOS-MEMS
Kevin M. Frederick
Masters Thesis, Carnegie Mellon University, Pittsburgh, Pennsylvania <"www.ece.cmu.edu/~mems/pubs/pdfs/ece/ms.../0090_frederick-2003.pdf" (5 February, 2010)>
Abstract
Nuclear Magnetic Resonance (NMR) on micro-liter samples using the Force Detection NMR (FDNMR) method will enable mobile and embedded detection of many elements without a multi-tesla superconducting magnet. This report presents a FDNMR sensor which has the ability to detect hydrogen of a
0.52 mL water sample in a 1 tesla magnetic field. The sensor is a micromachined cantilevered paddle within a CMOS chip measuring 2.5 mm x 2.5 mm x 540 mm with integrated amplification electronics.
To begin the paddle fabrication, a 30 mm thick silicon membrane with a thin layer of CMOS interconnect on top, is made by Deep Reactive Ion Etching (DRIE) the backside of the chip. The backside area is patterned with photoresist and etched into many close-proximity, slightly undercut high-aspect-ratio trenches to achieve a uniform membrane thickness. The resulting membrane measures 1370 mm by 1850 mm, with center to edge thickness variations less than 5 mm. A 0.6 mm x 0.6 mm x 0.25 mm piece of pure nickel is glued to the etched membrane surface as a detector magnet. Freon plasma etches trenches into the silicon dioxide interconnect layer not masked by aluminum, and a final DRIE extends the trenches through the silicon membrane. The final etch releases the folded-mass cantilever with 1 mm long spring beams and a 1.1 mm2 paddle surrounded by a capacitive bridge sensor to measure vertical displacement.
Integrated electronics drive the input and amplify the output of he balanced capacitive bridge which is made of lateral air gap capacitors between interdigitated micromechanical fingers. Force induced vertical cantilever displacement imbalances the bridge and the amplified output signal is measured by external test equipment. The bridge has the dynamic range to measure up to ±0.5 mm displacement at the maximum sensitivity of 5.12 mV/nm and up to ±2.0 mm with less sensitivity.
The FDNMR sensor is tested in response to electrostatic, mechanical, acceleration, and magnetic forces. The cantilevered paddle at 760 Torr resonates at 3.6 kHz (Q = 20) compared to 3.0 kHz (Q = 430) by simulation. The bridge output amplitude is linear with oscillating magnetic force amplitude. Estimated noise bandwidth is extracted from time-domain averaging of experimental data. Assuming a 1 MHz system bandwidth, 512 measurements equal a 1.95 kHz noise bandwidth and a 2.4 Å displacement noise floor with an SNR of 1. This displacement corresponds to a 4.4 pN oscillating force at 2.5 mTorr. A 100 Hz noise bandwidth will detect the 1.0 pN FDNMR force from a 0.52 mL water sample in a 1 tesla magnetic field.
Single-Sided NMR with a Halbach Magnet
Wei-Hao Chang, Jyh-Homg Chen and Lian-Pin Whang
Magnetic Resonance Imaging
2006, vol. 24(
pp. 1095-1102INIST-CNRS, Cote INIST : 19716, 35400014529870.0140
Abstract
A single-sided mobile NMR apparatus with a small Halbach magnet was constructed for the first time. It is lightweight, compact and exhibits good sensitivity. The weight of the device is only 2 kg, and the NMR signal of the pencil eraser block can be detected in one shot using the device. This study describes the characteristics of this instrument, including the profile of static magnetic flux density, B0, the sensitivity in the depth direction and its effectiveness in one-dimensional profiling. Its usefulness in differentiating soft materials and evaluating the extent of damage of a material is demonstrated based on T2 relaxation data. The moisture absorbance also can be observed
from the increase of the echo amplitude of the NMR spin echo signal.
Development of Halbach Magnet for Portable NMR device
N. Dogan1, R. Topkaya, H. Subas?, Y.Yerli, B.Rameev
Journal of Physics: Conference Series
153 (2009) 012047
doi:10.1088/1742-6596/153/1/012047
Abstract
Nuclear magnetic resonance (NMR) has enormous potential for various applications in industry as the on-line or at-line test/control device of process environments. Advantage of NMR is its non-destructive nature, because it does not require the measurement probe to have a contact with the tested media. Despite of the recent progress in this direction, application of NMR in industry is still very limited. This is related to the technical and analytical complications of NMR as a method, and high cost of NMR analyzers available at the market. However in many applications, NMR is a very useful technique to test various products and to monitor quantitatively industrial processes. Fortunately usually there is no need in a high-field superconducting magnets to obtain the high-resolution spectra with the detailed information on chemical shifts and coupling-constant. NMR analyzers are designed to obtain the relaxation parameters by measuring the NMR spectra in the time domain rather than in frequency domain. Therefore it is possible to use small magnetic field (and low frequency of 2-60 MHz) in NMR systems, based on permanent magnet technology, which are specially designed for specific at-line and on-line process applications. In this work we present the permanent magnet system developed to use in the portative NMR devices. We discuss the experimental parameters of the designed Halbach magnet system and compare them with results of theoretical modelling.
Design and Analysis of the Novel Test Tube Magnet for Portable NMR Device
Jizhong Chen, Yiming Zhang, and Jijun Xiao
IEEE Transactions on Magnetics
Volume: 43(9) Part 1 2007, 3555-3557
DOI:10.2529/PIERS060907042202
Abstract
The paper presents a novel test tube magnet (TTM) for Portable NMR device, which is composed of a dipole cylinder magnet and a hemi-cylinder or a hemi-sphere magnet. The hemi-cylinder or the hemi-sphere magnet is attached to one end of the dipole cylinder magnet, so that the whole magnet is shaped like a test tube. TTM generates a wide diameter spherical volume (DSV) with a high magnetic field homogeneity, which makes the device more applicable for portable NMR. The two configurations were simulated with three-dimensional finite-element methods. Flux density elements are effectively corrected in the DSV. The homogeneity increases, the magnet volumes and mass are markedly decreased, and the construction is very reasonable. Taken together the new designs have improved characteristics for portable NMR.
Permanent Magnets for Production and Use of High Energy Particle Beams
Klaus Halbach
8th Intern. Workshop on Rare Earth Magnets and their Appl., Dayton, Ohio, 6 May 1985
LBL-19285; CONF-850534-1
OSTI ID: 5844976; Legacy ID: DE85009934
Abstract
In the last few years, permanent magnet systems have begun to play a dominant role in the generation of synchrotron radiation and the operation of free electron lasers. Similarly, permanent magnets can lead to significant improvements of accelerators and systems that use them. The general conditions are discussed under which one can expect benefits from permanent magnets, and a number of specific applications will be described in detail.
Hills.Wright.Gillies.Low.Field.Low.Cost.Halbach.Magnet.for.Easy.NMR.pdf