title: Sensitization of a stray-field NMR to vibrations: a potential for MR elastometry with a portable NMR sensor.
abstract: An NMR signal from a sample in a constant stray field of a portable NMR sensor is sensitized to vibrations. The CPMG sequence is synchronized to vibrations so that the constant gradient becomes an "effective" square-wave gradient, leading to the vibration-induced phase accumulation. The integrating nature of the spot measurement, combined with the phase distribution due to a non-uniform gradient and/or a wave field, leads to a destructive interference, the drop in the signal intensity and changes in the echo train shape. Vibrations with amplitudes as small as 140 nm were reliably detected with the permanent gradient of 12.4 T/m. The signal intensity depends on the phase offset between the vibrations and the pulse sequence. This approach opens the way for performing elastometry and micro-rheology measurements with portable NMR devices beyond the walls of a laboratory. Even without synchronization, if a vibration frequency is comparable to 1/2TE of the CPMG sequence, the signal can be severely affected, making it important for potential industrial applications of stray-field NMR.
authors.affiliation: MRI Centre, Department of Physics, University of New Brunswick, Fredericton, New Brunswick E3B 5A3, Canada. Electronic address: mast@unb.ca.
authors.forename: Igor
authors.initials: I
authors.lastname: Mastikhin
authors.affiliation: MRI Centre, Department of Physics, University of New Brunswick, Fredericton, New Brunswick E3B 5A3, Canada.
authors.forename: Marie
authors.initials: M
authors.lastname: Barnhill
mesh_terms: D054459:Elasticity Imaging Techniques / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005240:Feasibility Studies; D007089:Image Enhancement / Q000295:instrumentation* / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation* / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation* / Q000379:methods; D008904:Miniaturization; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014732:Vibration
keywords: CPMG; Constant gradient; Elastometry; Portable NMR; Single-sided NMR; Stray field; Vibrations