Application of Ultra-Low Field HTS-SQUID NMR/MRI to Contaminant Detection in Food

We constructed an ultra-low field nuclear magnetic resonance (NMR)/magnetic resonance imaging (MRI) system utilizing a high-temperature superconductor (HTS) SQUID and permanent magnet for application of contaminant detection in food and drink. In order to compensate shortage of signal-to-noise ratio of the HTS-SQUID-based system, a pair permanent magnet of 1.1 T was employed for prepolarization field. It was combined with a sample transfer apparatus, which transferred a water sample with contaminant in a 10-ml glass bottle from the magnet to under the SQUID magnetometer within 0.5 s. Feasibility of contaminant detection in drink was demonstrated using the system by measuring NMR and 1-D MRI of water samples including contaminants of stainless steel, aluminum, and polymer. 2-D MRI measurement of a sample with partitioned water by silicone bulk was demonstrated employing the filtered back projection reconstruction method.