Fabrication of NMR — Microsensors for nanoliter sample volumes

Dechow, Jörn; Forchel, A.; Lanz, Titus; Haase, Axel

doi:10.1016/s0167-9317(00)00368-3

Cited by 48 publications

(29 citation statements)

References 5 publications

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“…13 Among the planar microcoils used for NMR experiments, [8][9][10][11]19,20 the highest average SNR per acquisition of 60 was achieved with a circular spiral microcoil made of Cu, having an outer radius of 1000 µm, 4 turns and a sample volume of 470 nL located 50 µm above the coil center. Other reported planar architectures include stacked multiple planar microcoils.…”

Section: Appendixmentioning

confidence: 99%

“…Micro-NMR systems reported previously have been realized with several types of coils, such as Helmholtz, [1][2][3] solenoidal, 4-6 planar [7][8][9][10][11][12] or even micro-strip lines. 13 These systems operate at different Larmor frequencies with values varying in a wide range, from 63.88 MHz when the externally applied DC magnetic field (MF) has the magnetic field strength (MFS, i.e.…”

Section: Introductionmentioning

confidence: 99%

“…13 These systems operate at different Larmor frequencies with values varying in a wide range, from 63.88 MHz when the externally applied DC magnetic field (MF) has the magnetic field strength (MFS, i.e. magnetic flux density) B 0 = 1.5 T, 14 to as high as 500 MHz when B 0 = 11 T. 8 The first generic expression for the signal-to-noise ratio (SNR) for an NMR experiment was formulated almost 40 years ago by D. Hoult et al: 15 …”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Design of planar microcoil-based NMR probe ensuring high SNR

2017

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A microNMR probe for ex vivo applications may consist of at least one microcoil, which can be used as the oscillating magnetic field (MF) generator as well as receiver coil, and a sample holder, with a volume in the range of nanoliters to micro-liters, placed near the microcoil. The Signal-to-Noise ratio (SNR) of such a probe is, however, dependent not only on its design but also on the measurement setup, and the measured sample. This paper introduces a performance factor P independent of both the proton spin density in the sample and the external DC magnetic field, and which can thus assess the performance of the probe alone. First, two of the components of the P factor (inhomogeneity factor K and filling factor η) are defined and an approach to calculate their values for different probe variants from electromagnetic simulations is devised. A criterion based on dominant component of the magnetic field is then formulated to help designers optimize the sample volume which also affects the performance of the probe, in order to obtain the best SNR for a given planar microcoil. Finally, the P factor values are compared between different planar microcoils with different number of turns and conductor aspect ratios, and planar microcoils are also compared with conventional solenoids. These comparisons highlight which microcoil geometry-sample volume combination will ensure a high SNR under any external setup.

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Section: Appendixmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Design of planar microcoil-based NMR probe ensuring high SNR

2017

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“…More recently, coils have been combined with sample volumes on glass [7] and deposited on plastic [8], and implantable devices have been developed [9]. The best performance is obtained on insulating substrates [10].…”

Section: Related Contentmentioning

confidence: 99%

Micro-coils for MR spectroscopy by deep silicon etching

Syms¹,

Ahmad²,

Young³

et al. 2005

J. Phys.: Conf. Ser.

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A process for batch fabrication of low-cost microcoils for magnetic resonance spectroscopy is demonstrated. Conductors are fabricated on oxidised silicon substrates by electroplating metals inside a deep photoresist mould, and passivated using an epoxy-based resist. Through-wafer deep reactive ion etching is used to define sample volumes and stencil cuts around each die, and dies are separated by snap-out. Single-coil and multiple-coil sensors are constructed by stacking parts on baseplates fabricated on the same wafer. Single-turn coils have a Q-factor of ≈ 15 at 63.6 MHz, and Helmholtz coils a Q-factor of ≈ 13. Magnetic resonance imaging and spectroscopy are performed, and a SNR of 900 is achieved.

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“…In recent years significant advances in the development and fabrication of µ-coils (size < 1 mm) for NMR have continued [15][16][17]. Both planar surface µ-coils and solenoid µ-coils have been developed for a wide range of applications [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]. To enhance sensitivity for tiny samples, much of the work with micro-coils has utilized the high fields produced by strong super-conducting magnets, only a limited few have been directed towards optimization at low magnetic field strengths [37].…”

Section: Introductionmentioning

confidence: 99%

Bioagent detection using miniaturized NMR and nanoparticle amplification : final LDRD report.

Clewett¹,

Adams²,

Fan³

et al. 2006

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This LDRD program was directed towards the development of a portable micro-nuclear magnetic resonance (µ-NMR) spectrometer for the detection of bioagents via induced amplification of solvent relaxation based on superparamagnetic nanoparticles. The first component of this research was the fabrication and testing of two different micro-coil (µ-coil) platforms: namely a planar spiral NMR µ-coil and a cylindrical solenoid NMR µ-coil. These fabrication techniques are described along with the testing of the NMR performance for the individual coils. The NMR relaxivity for a series of water soluble FeMn oxide nanoparticles was also determined to explore the influence of the nanoparticle size on the observed NMR relaxation properties. In addition, The use of commercially produced superparamagnetic iron oxide nanoparticles (SPIONs) for amplification via NMR based relaxation mechanisms was also demonstrated, with the lower detection limit in number of SPIONs per nanoliter (nL) being determined.* Author to whom correspondence should be addressed: tmalam@sandia.gov 4 AcknowledgementsThe progress made in this LDRD project is the result of contributions from a number of team members both here at Sandia National Laboratories, at the University of New Mexico and the company New Mexico Resonance. These members include C. The development and testing of two different µ-coil platforms for nuclear magnetic resonance (NMR) detection were completed under this LDRD project. The performance of these NMR µ-coils allowed the demonstration of SPION (superparamagnetic iron oxide nanoparticle) amplification via induced changes in the NMR relaxation rates of the carrier solvent water. A detection limit of 10 particles/nL was experimentally measured for the first prototype solenoid µ-coil design. These results clearly show that nanoparticle amplification for µ-NMR can be used for detection of bioagents. List of Tables

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Fabrication of NMR — Microsensors for nanoliter sample volumes

Cited by 48 publications

References 5 publications

Design of planar microcoil-based NMR probe ensuring high SNR

Design of planar microcoil-based NMR probe ensuring high SNR

Micro-coils for MR spectroscopy by deep silicon etching

Bioagent detection using miniaturized NMR and nanoparticle amplification : final LDRD report.

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