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

doi:10.1073/pnas.0711505105

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

*Department of Physics, University of California, Berkeley, CA 94720-7300;
^†Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720;
^‡Time and Frequency Division, National Institute of Standards and Technology, 325 Broadway, Boulder, CO 80305; and
^§Department of Chemistry, University of California, Berkeley, CA 94720-7300

Contributed by A. Pines, December 18, 2007 (received for review October 3, 2007)

Abstract

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 relaxation-free (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 × 10¹³ protons in a volume of 1 mm³, prepolarized in a 10-kG field, can be detected with a signal-to-noise ratio of ≈3. This level of sensitivity is competitive with that demonstrated by microcoils in 100-kG magnetic fields, without requiring superconducting magnets.

Footnotes

^¶To whom correspondence should be addressed. E-mail: pines{at}berkeley.edu
Author contributions: M.P.L., D.B., J.K., and A.P. designed research; M.P.L., I.M.S., V.S., D.J.M., and S.X. performed research; V.S. and S.K. contributed new reagents/analytic tools; M.P.L. analyzed data; and M.P.L., D.B., S.K., J.K., D.J.M., and S.X. wrote the paper.
The authors declare no conflict of interest.