Sensors based on the measurement of nuclear magnetic resonance (NMR) relaxation times have been increasing in popularity, due in part to developments in permanent magnet technology. Such sensors tend to measure the spin-lattice (longitudinal) relaxation time T1, or the effective spin-spin (transverse) relaxation time T2eff. It is important when developing sensors that there are a range of safe and repeatable calibration samples to aid in their calibration and testing. For the spin-spin relaxation times different viscosities of PDMS oil provide a suitable range of safe test materials. However, for the spin-lattice relaxation times, available options are not as safe to use and typically consist of different concentrations of Nickel Sulphate or Copper Sulfate solutions. In this work we report the use of solutions and gels comprising full fat milk powder as a safe and inexpensive material that can affect the longitudinal relaxation Time over a very wide range of values. We demonstrate that concentrations in distilled water from 5% to 64% give T1 values from 1.8s down to 348 ms respectively. In addition to demonstrating their effectiveness for magnetic resonance sensors, validation of the range of T1 values is undertaken on a high field clinical MRI system.
Novel food-safe spin-lattice relaxation time calibration samples for use in magnetic resonance sensor development
Published: 14 November 2017 by MDPI AG in Proceedings in 4th International Electronic Conference on Sensors and Applications session Physical Sensors
MDPI AG, Volume 2; 10.3390/ecsa-4-04916