Subpicotesla atomic magnetometry with a microfabricated vapour cell

Shah, Vishal; Knappe, Svenja; Schwindt, Peter D. D.; Kitching, John

doi:10.1038/nphoton.2007.201

Cited by 347 publications

(253 citation statements)

References 25 publications

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“…2(b) after correcting for the finite bandwidth of the magnetometer, revealing a simple structure consisting of two peaks (offsets inserted for visual clarity). This spectrum is in agreement with the discussion of 13 The dependences of the amplitudes of the low-and high-frequency peaks on the pulse area are shown by triangles and squares, respectively in Fig. 3 (a).…”

supporting

confidence: 89%

“…Furthermore, in contrast to SQUIDs, atomic magnetometers do not require cryogenics. We achieve efficient coupling to small samples by making use of millimeter-scale magnetometers (13) manufactured using microfabrication techniques (14). These factors allow us to work with an 80-μL detection volume, 25 and 6000 times smaller than the quantities used in the Earth-field studies of Refs.…”

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confidence: 99%

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Optical detection of NMR J-spectra at zero magnetic field

Ledbetter

Crawford

Pines

et al. 2009

Journal of Magnetic Resonance

111

123

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Scalar couplings of the form JI 1 ·I 2 between nuclei impart valuable information about molecular structure to nuclear magnetic-resonance spectra. Here we demonstrate direct detection of J-spectra due to both heteronuclear and homonuclear J-coupling in a zero-field environment where the Zeeman interaction is completely absent. We show that characteristic functional groups exhibit distinct spectra with straightforward interpretation for chemical identification.Detection is performed with a microfabricated optical atomic magnetometer, providing high sensitivity to samples of microliter volumes. We obtain 0.1 Hz linewidths and measure scalar-coupling parameters with 4-mHz statistical uncertainty. We anticipate that the technique described here will provide a new modality for high-precision "J spectroscopy" using small samples on microchip devices for multiplexed screening, assaying, and sample identification in chemistry and biomedicine.

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confidence: 89%

mentioning

confidence: 99%

Optical detection of NMR J-spectra at zero magnetic field

Ledbetter

Crawford

Pines

et al. 2009

Journal of Magnetic Resonance

111

123

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“…Optical pumping and probing of the alkali vapor are accomplished with a single laser beam (7). In addition to integration of sensor and microfluidic channel on a single chip, a key feature distinguishing the present work from previous applications of atomic magnetometers to the detection of NMR (15,16) or MRI (2) is that the detection region (both magnetometer and nuclear sample) is at zero magnetic field.…”

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confidence: 99%

Zero-field remote detection of NMR with a microfabricated atomic magnetometer

Ledbetter

Savukov

Budker

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

125

108

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We demonstrate remote detection of nuclear magnetic resonance (NMR) with a microchip sensor consisting of a microfluidic channel and a microfabricated vapor cell (the heart of an atomic magnetometer). Detection occurs at zero magnetic field, which allows operation of the magnetometer in the spin-exchange relaxationfree (SERF) regime and increases the proximity of sensor and sample by eliminating the need for a solenoid to create a leading field. We achieve pulsed NMR linewidths of 26 Hz, limited, we believe, by the residence time and flow dispersion in the encoding region. In a fully optimized system, we estimate that for 1 s of integration, 7 ؋ 10 13 protons in a volume of 1 mm 3 , prepolarized in a 10-kG field, can be detected with a signal-to-noise ratio of Ϸ3. This level of sensitivity is competitive with that demonstrated by microcoils in 100-kG magnetic fields, without requiring superconducting magnets.microfluidics ͉ signal-to-noise ratio ͉ mass-limited sample R emote detection of nuclear magnetic resonance (NMR) (1), in which polarization, encoding or evolution, and detection are spatially separated, has recently attracted considerable attention in the context of magnetic resonance imaging (2), microfluidic flow profiling (3, 4), and spin-labeling (5). Detection can be performed with superconducting quantum interference devices (SQUIDs), inductively at high field as in refs. 3-5 or with atomic magnetometers as in ref. 2. To most efficiently detect the flux from the nuclear sample, it is typically necessary to match the physical dimensions of the sensor and the sample. Thus, small, sensitive detectors of magnetic flux reduce the detection volume, thereby reducing the quantity of analyte. Microfabricated atomic magnetometers (6) with sensor dimensions on the order of 1 mm operating in the spin-exchange relaxation-free (SERF) regime (8) have recently demonstrated sensitivities of Ϸ0.7 nG/ ͌ Hz (7), with projected theoretical sensitivities several orders of magnitude higher. (In this article, we use Gaussian units; 1 nG ϭ 100 fT.)In this work, we demonstrate remote detection of pulsed and continuous-wave (CW) NMR with a compact sensor assembly consisting of an alkali vapor cell and microfluidic channel, fabricated with lithographic patterning and etching of silicon. We realize pulsed NMR linewidths of Ϸ26 Hz, limited, we believe, by residence time and flow dispersion in the encoding region. Estimates of the fundamental sensitivity limit for an optimized system, assuming a modest 10-kG prepolarizing field, indicate detection limits competitive with those demonstrated by microcoils in superconducting magnets (9-14). Hence, the technique described here offers a promising solution to NMR of mass-limited samples-for example, in the screening of new drugs-without requiring superconducting magnets.The atomic magnetometer operates in the SERF regime (achieved when the Larmor precession frequency is small compared with the spin exchange rate), currently the most sensitive technique in atomic magnetometry. Optical pum...

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“…This limits the dynamic range of the magnetometer, but it could still be useful for biomedical applications, where high sensitivities are required in magneticallyshielded environments. In a tabletop setup, we measured sensitivities around 70 fT/Hz 1/2 in a MEMS vapor cell of 2 x 3 x 1 mm 3 volume [18] (Figure 1, 2007, grey online). The configuration was simplified by using a single circularly-polarized beam [8] to replace two perpendicular beams of a standard pump-probe configuration [16].…”

Section: Introductionmentioning

confidence: 99%