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Liang J, Davoodi H, Wadhwa S, Badilita V, Korvink JG. Broadband stripline Lenz lens achieves 11 × NMR signal enhancement. Sci Rep 2024; 14:1645. [PMID: 38238376 PMCID: PMC10796323 DOI: 10.1038/s41598-023-50616-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 12/22/2023] [Indexed: 01/22/2024] Open
Abstract
A Lenz lens is an electrically passive conductive element that, when placed in a time-varying magnetic field, acts as a magnetic flux concentrator or a magnetic lens. In the realm of nuclear magnetic resonance (NMR), Lenz lenses have been exploited as electrically passive metallic radiofrequency interposers placed between a sample and a tuned or untuned NMR detector in order to focus the [Formula: see text]-field of the detector onto a smaller sample space. Here we explore a novel embodiment of the Lenz lens, which acts as a non-resonant stripline interposer, i.e., the [Formula: see text]-field acts along the longitudinal volume of a sample container, such as a capillary or other microfluidic channel that is coincident with the axis of the stripline. The almost vanishing self-resonance of the stripline Lenz lens, at frequencies relevant for NMR, leads to a desirable [Formula: see text]-field amplitude that is nearly perfectly uniform across the sample and hence lacking a characteristic sinusoidal modal shape. The action of Lenz' law ensures that no stray [Formula: see text]-field is found outside of the stripline's active volume. Because the stripline Lenz lens does not rely on its own geometry to achieve resonance, its frequency response is thus widely broadband for field enhancements up to a factor of 11, with only the external driving resonator properties governing the overall resonant behaviour. We explore the use of the stripline Lenz lens with a sub-nanolitre sample volume, readily detecting 4 isotopes with resonances ranging from 125.76 to 500 MHz. The concept holds potential for the NMR study of thin films, small biological samples, as well as the in situ study of battery materials.
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Affiliation(s)
- Jianyi Liang
- Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), 76344, Eggenstein-Leopoldshafen, Germany
| | | | | | - Vlad Badilita
- Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), 76344, Eggenstein-Leopoldshafen, Germany.
| | - Jan G Korvink
- Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), 76344, Eggenstein-Leopoldshafen, Germany.
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2
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Lepucki P, Dioguardi AP, Karnaushenko D, Schmidt OG, Grafe HJ. The normalized limit of detection in NMR spectroscopy. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 332:107077. [PMID: 34634649 DOI: 10.1016/j.jmr.2021.107077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 09/19/2021] [Accepted: 09/20/2021] [Indexed: 06/13/2023]
Abstract
We derive the normalized limit of detection for frequency space (nLODf) as a parameter to measure the sensitivity of an NMR spectroscopy setup. nLODf is independent of measurement settings such as bandwidth or number of measurement points, and allows to compare performances of different setups. We demonstrate the usefulness of the new nLODf by comparing the sensitivity of NMR setups from various publications, which all use microcoils. Finally, we want to propose a standard measurement and report format for the sensitivity of new NMR setups.
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Affiliation(s)
- Piotr Lepucki
- IFW Dresden, Institut für Festkörperforschung, Helmholtzstraße 20, 01069 Dresden, Germany.
| | - Adam P Dioguardi
- IFW Dresden, Institut für Festkörperforschung, Helmholtzstraße 20, 01069 Dresden, Germany.
| | - Daniil Karnaushenko
- IFW Dresden, Institut für Integrative Nanowissenschaften, Helmholtzstraße 20, 01069 Dresden, Germany.
| | - Oliver G Schmidt
- IFW Dresden, Institut für Integrative Nanowissenschaften, Helmholtzstraße 20, 01069 Dresden, Germany; TU Dresden, Nanophysik, Häckelstraße 3, 01069 Dresden, Germany; TU Chemnitz, Material Systems for Nanoelectronics, Straße der Nationen 62, 09111 Chemnitz, Germany.
| | - Hans-Joachim Grafe
- IFW Dresden, Institut für Festkörperforschung, Helmholtzstraße 20, 01069 Dresden, Germany.
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3
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Sharma M, Utz M. Modular transmission line probes for microfluidic nuclear magnetic resonance spectroscopy and imaging. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 303:75-81. [PMID: 31026668 DOI: 10.1016/j.jmr.2019.04.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 03/30/2019] [Accepted: 04/09/2019] [Indexed: 06/09/2023]
Abstract
Microfluidic NMR spectroscopy can probe chemical and bio-chemical processes non-invasively in a tightly controlled environment. We present a dual-channel modular probe assembly for high efficiency microfluidic NMR spectroscopy and imaging. It is compatible with a wide range of microfluidic devices, without constraining the fluidic design. It collects NMR signals from a designated sample volume on the device with high sensitivity and resolution. Modular design allows adapting the detector geometry to different experimental conditions with minimal cost, by using the same probe base. The complete probe can be built from easily available parts. The probe body mainly consists of prefabricated aluminium profiles, while the probe circuit and detector are made from printed circuit boards. We demonstrate a double resonance HX probe with a limit of detection of 1.4 nmol s-1/2 for protons at 600 MHz, resolution of 3.35 Hz, and excellent B1 homogeneity. We have successfully acquired 1H-13C and 1H-15N heteronuclear correlation spectra (HSQC), including a 1H-15N HSQC spectrum of 1 mM 15N labeled ubiquitin in 2.5 μl of sample volume.
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Affiliation(s)
- Manvendra Sharma
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - Marcel Utz
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom
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4
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Mompeán M, Sánchez-Donoso RM, de la Hoz A, Saggiomo V, Velders AH, Gomez MV. Pushing nuclear magnetic resonance sensitivity limits with microfluidics and photo-chemically induced dynamic nuclear polarization. Nat Commun 2018; 9:108. [PMID: 29317665 PMCID: PMC5760532 DOI: 10.1038/s41467-017-02575-0] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 12/11/2017] [Indexed: 12/03/2022] Open
Abstract
Among the methods to enhance the sensitivity of nuclear magnetic resonance (NMR) spectroscopy, small-diameter NMR coils (microcoils) are promising tools to tackle the study of mass-limited samples. Alternatively, hyperpolarization schemes based on dynamic nuclear polarization techniques provide strong signal enhancements of the NMR target samples. Here we present a method to effortlessly perform photo-chemically induced dynamic nuclear polarization in microcoil setups to boost NMR signal detection down to sub-picomole detection limits in a 9.4T system (400 MHz 1H Larmor frequency). This setup is unaffected by current major drawbacks such as the use of high-power light sources to attempt uniform irradiation of the sample, and accumulation of degraded photosensitizer in the detection region. The latter is overcome with flow conditions, which in turn open avenues for complex applications requiring rapid and efficient mixing that are not easily achievable on an NMR tube without resorting to complex hardware. Nuclear magnetic resonance (NMR) spectroscopy is a powerful technique with an inherently low sensitivity. Here, the authors present a combination of microcoils with photo-chemically induced dynamic nuclear polarization to boost NMR sensitivity down to sub-picomole detection limits.
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Affiliation(s)
- Miguel Mompeán
- Instituto Regional de Investigación Científica Aplicada (UCLM), Avda Camilo José Cela s/n, 13071, Ciudad Real, Spain
| | - Rosa M Sánchez-Donoso
- Instituto Regional de Investigación Científica Aplicada (UCLM), Avda Camilo José Cela s/n, 13071, Ciudad Real, Spain.,Laboratory of BioNanoTechnology, Wageningen University, PO Box 8038, 6700, EK Wageningen, The Netherlands
| | - Antonio de la Hoz
- Instituto Regional de Investigación Científica Aplicada (UCLM), Avda Camilo José Cela s/n, 13071, Ciudad Real, Spain
| | - Vittorio Saggiomo
- Laboratory of BioNanoTechnology, Wageningen University, PO Box 8038, 6700, EK Wageningen, The Netherlands
| | - Aldrik H Velders
- Instituto Regional de Investigación Científica Aplicada (UCLM), Avda Camilo José Cela s/n, 13071, Ciudad Real, Spain. .,Laboratory of BioNanoTechnology, Wageningen University, PO Box 8038, 6700, EK Wageningen, The Netherlands. .,MAGNEtic resonance research FacilitY-MAGNEFY, Wageningen University & Research, PO Box 8038, 6700, EK Wageningen, The Netherlands.
| | - M Victoria Gomez
- Instituto Regional de Investigación Científica Aplicada (UCLM), Avda Camilo José Cela s/n, 13071, Ciudad Real, Spain
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Fugariu I, Soong R, Lane D, Fey M, Maas W, Vincent F, Beck A, Schmidig D, Treanor B, Simpson AJ. Towards single egg toxicity screening using microcoil NMR. Analyst 2017; 142:4812-4824. [DOI: 10.1039/c7an01339f] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Planar NMR microcoils are evaluated, their application to single eggs is demonstrated, and their potential for studying smaller single cells is discussed.
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Affiliation(s)
- I. Fugariu
- Dept. of Chemistry and Dept. Phys. Env. Sci
- University of Toronto at Scarborough
- Scarborough
- Canada
| | - R. Soong
- Dept. of Chemistry and Dept. Phys. Env. Sci
- University of Toronto at Scarborough
- Scarborough
- Canada
| | - D. Lane
- Dept. of Chemistry and Dept. Phys. Env. Sci
- University of Toronto at Scarborough
- Scarborough
- Canada
| | - M. Fey
- Bruker Biospin
- Billerica
- USA
| | | | | | - A. Beck
- Bruker Biospin
- 8117 Fällanden
- Switzerland
| | | | - B. Treanor
- Dept. of Biological Science
- University of Toronto at Scarborough
- Scarborough
- Canada
| | - A. J. Simpson
- Dept. of Chemistry and Dept. Phys. Env. Sci
- University of Toronto at Scarborough
- Scarborough
- Canada
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Finch G, Yilmaz A, Utz M. An optimised detector for in-situ high-resolution NMR in microfluidic devices. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 262:73-80. [PMID: 26754062 DOI: 10.1016/j.jmr.2015.11.011] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 11/24/2015] [Accepted: 11/25/2015] [Indexed: 06/05/2023]
Abstract
Integration of high-resolution nuclear magnetic resonance (NMR) spectroscopy with microfluidic lab-on-a-chip devices is challenging due to limited sensitivity and line broadening caused by magnetic susceptibility inhomogeneities. We present a novel double-stripline NMR probe head that accommodates planar microfluidic devices, and obtains the NMR spectrum from a rectangular sample chamber on the chip with a volume of 2μl. Finite element analysis was used to jointly optimise the detector and sample volume geometry for sensitivity and RF homogeneity. A prototype of the optimised design has been built, and its properties have been characterised experimentally. The performance in terms of sensitivity and RF homogeneity closely agrees with the numerical predictions. The system reaches a mass limit of detection of 1.57nmols, comparing very favourably with other micro-NMR systems. The spectral resolution of this chip/probe system is better than 1.75Hz at a magnetic field of 7T, with excellent line shape.
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Affiliation(s)
- Graeme Finch
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - Ali Yilmaz
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - Marcel Utz
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom
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7
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Harel E. Lab-on-a-chip detection by magnetic resonance methods. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2010; 57:293-305. [PMID: 20667402 DOI: 10.1016/j.pnmrs.2010.05.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2007] [Accepted: 05/10/2010] [Indexed: 05/29/2023]
Affiliation(s)
- Elad Harel
- The James Franck Institute, University of Chicago, 929 E. 57th Street, GCIS E028, Chicago, IL 60637, USA.
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8
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Harel E. Magnetic resonance detection: spectroscopy and imaging of lab-on-a-chip. LAB ON A CHIP 2009; 9:17-23. [PMID: 19209329 DOI: 10.1039/b807036a] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
This mini-review is focused on the use of nuclear magnetic resonance (NMR) spectroscopy and imaging to study processes on lab-on-a-chip devices. NMR as an analytical tool is unmatched in its impact across nearly every area of science, from biochemistry and medicine to fundamental chemistry and physics. The controls available to the NMR spectroscopist or imager are vast, allowing for everything from high level structural determination of proteins in solution to detailed contrast imaging of organs in-vivo. Unfortunately, the weak nuclear magnetic moment of the nucleus requires that a very large number of spins be present for an inductively detectable signal, making the use of magnetic resonance as a detection modality for microfluidic devices especially challenging. Here we present recent efforts to combat the inherent sensitivity limitation of magnetic resonance for lab-on-a-chip applications. Principles and examples of different approaches are presented that highlight the flexibility and advantages of this type of detection modality.
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Affiliation(s)
- Elad Harel
- Department of Chemistry, University of California, Berkeley, CA 94720, USA.
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9
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Harel E, Pines A. Spectrally resolved flow imaging of fluids inside a microfluidic chip with ultrahigh time resolution. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2008; 193:199-206. [PMID: 18538599 DOI: 10.1016/j.jmr.2008.04.037] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2008] [Revised: 04/25/2008] [Accepted: 04/28/2008] [Indexed: 05/26/2023]
Abstract
Microfluidics has advanced to become a complete lab-on-a-chip platform with applications across many disciplines of scientific research. While optical techniques are primarily used as modes of detection, magnetic resonance (MR) is emerging as a potentially powerful and complementary tool because of its non-invasive operation and analytical fidelity. Two prevailing limitations currently inhibit MR techniques on microfluidic devices: poor sensitivity and the relatively slow time scale of dynamics that can be probed. It is commonly assumed that the time scale of observation of one variable limits the certainty with which one can measure the complementary variable. For example, short observation times imply poor spectral resolution. In this article, we demonstrate a new methodology that overcomes this fundamental limit, allowing in principle for arbitrarily high temporal resolution with a sensitivity across the entire microfluidic device several orders of magnitude greater than is possible by direct MR measurement. The enhancement is evidenced by recording chemically resolved fluid mixing through a complex 3D microfluidic device at 500 frames per second, the highest recorded in a magnetic resonance imaging experiment. The key to this development is combining remote detection with a time 'slicing' of its spatially encoded counterpart. Remote detection circumvents the problem of insensitive direct MR detection on a microfluidic device where the direct sensitivity is less than 10(-5) relative to traditional NMR, while the time slicing eliminates the constraints of the limited observation time by converting the time variable into a spatial variable through the use of magnetic field gradients. This method has implications for observing fast processes, such as fluid mixing, rapid binding, and certain classes of chemical reactions with sub millisecond time resolution and as a new modality for on-chip chromatography.
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Affiliation(s)
- Elad Harel
- Materials Sciences Division, Lawrence Berkeley National Laboratory, and Department of Chemistry, University of California, Berkeley, CA 94720, USA.
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Narkowicz R, Suter D, Niemeyer I. Scaling of sensitivity and efficiency in planar microresonators for electron spin resonance. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2008; 79:084702. [PMID: 19044371 DOI: 10.1063/1.2964926] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Electron spin resonance (ESR) of volume-limited samples or nanostructured materials can be made significantly more efficient by using microresonators whose size matches that of the structures under investigation. We describe a series of planar microresonators that show large improvements over conventional ESR resonators in terms of microwave conversion efficiency (microwave field strength for a given input power) and sensitivity (minimum number of detectable spins). We explore the dependence of these parameters on the size of the resonator and find that both scale almost linearly with the inverse of the resonator size. Scaling down the loops of the planar microresonators from 500 down to 20 mum improves the microwave efficiency and the sensitivity of these structures by more than an order of magnitude and reduces the microwave power requirements by more than two orders of magnitude.
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Affiliation(s)
- R Narkowicz
- Department of Physics, Technical University of Dortmund, D-44221 Dortmund, Germany
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11
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Baxan N, Rabeson H, Pasquet G, Châteaux JF, Briguet A, Morin P, Graveron-Demilly D, Fakri-Bouchet L. Limit of detection of cerebral metabolites by localized NMR spectroscopy using microcoils. CR CHIM 2008. [DOI: 10.1016/j.crci.2007.07.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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12
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Harel E, Schröder L, Xu S. Novel detection schemes of nuclear magnetic resonance and magnetic resonance imaging: applications from analytical chemistry to molecular sensors. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2008; 1:133-163. [PMID: 20636077 DOI: 10.1146/annurev.anchem.1.031207.113018] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Nuclear magnetic resonance (NMR) is a well-established analytical technique in chemistry. The ability to precisely control the nuclear spin interactions that give rise to the NMR phenomenon has led to revolutionary advances in fields as diverse as protein structure determination and medical diagnosis. Here, we discuss methods for increasing the sensitivity of magnetic resonance experiments, moving away from the paradigm of traditional NMR by separating the encoding and detection steps of the experiment. This added flexibility allows for diverse applications ranging from lab-on-a-chip flow imaging and biological sensors to optical detection of magnetic resonance imaging at low magnetic fields. We aim to compare and discuss various approaches for a host of problems in material science, biology, and physics that differ from the high-field methods routinely used in analytical chemistry and medical imaging.
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Affiliation(s)
- Elad Harel
- Department of Chemistry, University of California, Berkeley, 94720, USA.
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13
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Baxan N, Rengle A, Pasquet G, Châteaux JF, Briguet A, Morin P, Fakri-Bouchet L. Investigation of NMR limits of detection for implantable microcoils. ACTA ACUST UNITED AC 2007; 2007:4194-7. [PMID: 18002927 DOI: 10.1109/iembs.2007.4353261] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Although NMR has the ability to investigate biological systems non-destructively, its low sensitivity primarily has hampered their investigation compared to other analytical techniques. Therefore, optimi zing radio frequency (RF) coils to improve sensitivity do offer benefits in MR spectroscopy (MRS). Sensitivity may be improved for mass- and volume-limited samples if the size of the detection RF coils matches the sample size. In this paper, the mass- and concentration-limit of detection (LOD(m), LOD(c)) for an implantable microcoil will be estimated by MRS measurements and then compared with their analytical values. For a sample containing a solution of several cerebral metabolites, for the Choline case, the LODm is 5.7 . 10(-9)mol and LODc of 3.8 mM. These preliminary results enable to open largely the biomedical applications based on cerebral metabolism investigation on small animal experiments.
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Affiliation(s)
- N Baxan
- CREATIS-LRMN, CNRS, UMR 5220, Villeurbanne, France
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14
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van Bentum PJM, Janssen JWG, Kentgens APM, Bart J, Gardeniers JGE. Stripline probes for nuclear magnetic resonance. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2007; 189:104-13. [PMID: 17890116 DOI: 10.1016/j.jmr.2007.08.019] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Revised: 08/24/2007] [Accepted: 08/31/2007] [Indexed: 05/17/2023]
Abstract
A novel route towards chip integrated NMR analysis is evaluated. The basic element in the design is a stripline RF 'coil' which can be defined in a single layer lithographic process and which is fully scalable to smaller dimensions. The sensitivity of such a planar structure can be superior to that of a conventional 3D helix. The basic properties, such as RF field strength, homogeneity and susceptibility broadening are discussed in detail. Secondary effects related to the thermal characteristics are discussed in simplified models. Preliminary NMR tests of basic solid and liquid samples measured at 600 MHz confirm the central findings of the design study. It is concluded that the stripline structure can be a valuable addition to the NMR toolbox; it combines high sensitivity with low susceptibility broadening and high power handling capabilities in a simple scalable design.
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Affiliation(s)
- P J M van Bentum
- Institute for Molecules and Materials, Radboud University, Toernooiveld 1, 6525ED Nijmegen, The Netherlands
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Ehrmann K, Pataky K, Stettler M, Wurm FM, Brugger J, Besse PA, Popovic R. NMR spectroscopy and perfusion of mammalian cells using surface microprobes. LAB ON A CHIP 2007; 7:381-3. [PMID: 17330170 DOI: 10.1039/b613240e] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
NMR spectra of mammalian cells are taken using surface microprobes that are based on microfabricated planar coils. The surface microprobe resembles a miniaturized Petri dish commonly used in biological research. The diameter of the planar coils is 1 mm. Chinese Hamster Ovaries are immobilized in a uniform layer on the microprobe surface or patterned by an ink-jet printer in the centre of the microcoil, where the rf-field of the planar microcoil is most uniform. The acquired NMR spectra show the prevalent metabolites found in mammalian cells. The volumes of the detected samples range from 25 nL to 1 nL (or 50,000 to 1800 cells). With an extended set-up that provides fluid inlets and outlets to the microprobe, the cells can be perfused within the NMR-magnet while constantly taking NMR spectra. Perfusion of the cells opens the way to increased cell viability for long acquisitions or to analysis of the cells' response to environmental change.
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Affiliation(s)
- Klaus Ehrmann
- Microsystems Laboratory, EPFL-Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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