title: NMR analysis on microfluidic devices by remote detection.
abstract: We present a novel approach to perform high-sensitivity NMR imaging and spectroscopic analysis on microfluidic devices. The application of NMR, the most information-rich spectroscopic technique, to microfluidic devices remains a challenge because the inherently low sensitivity of NMR is aggravated by small fluid volumes leading to low NMR signal and geometric constraints resulting in poor efficiency for inductive detection. We address the latter by physically separating signal detection from encoding of information with remote detection. Thereby, we use a commercial imaging probe with sufficiently large diameter to encompass the entire device, enabling encoding of NMR information at any location on the chip. Because large-diameter coils are too insensitive for detection, we store the encoded information as longitudinal magnetization and flow it into the outlet capillary. There, we detect the signal with optimal sensitivity, using a solenoidal microcoil, and reconstruct the information encoded in the fluid. We present a generally applicable design for a detection-only microcoil probe that can be inserted into the bore of a commercial imaging probe. Using hyperpolarized 129Xe gas, we show that this probe enables sensitive reconstruction of NMR spectroscopic information encoded by the large imaging probe while keeping the flexibility of a large coil.
authors.affiliation: Materials Sciences Division, Lawrence Berkeley National Laboratory, and Department of Chemistry, University of California Berkeley, Berkeley, California 94720, USA. eemoore@berkeley.edu
authors.forename: Erin E
authors.initials: EE
authors.lastname: McDonnell
authors.forename: SongI
authors.initials: S
authors.lastname: Han
authors.forename: Christian
authors.initials: C
authors.lastname: Hilty
authors.forename: Kimberly L
authors.initials: KL
authors.lastname: Pierce
authors.forename: Alexander
authors.initials: A
authors.lastname: Pines
mesh_terms: D046210:Microfluidic Analytical Techniques / Q000295:instrumentation / Q000379:methods*; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000295:instrumentation / Q000379:methods*; D014979:Xenon Isotopes
chemical_list: D014979:Xenon Isotopes