NMR and MRI obtained with high transition temperature DC SQUIDs

We have measured nuclear magnetic resonance (NMR) signals from several samp les at room temperature in magnetic fields ranging from about 0.05 mT to 2 mT using a spectrometer based on a high-T-c de SQUID (high transition tempe rature de Superconducting QUantum Interference Device). We are able to obse rve proton signals from 1 mL of mineral oil in 2 mT in a single transient. The sensitivity of this system has also allowed the detection of proton NMR at magnetic fields as low as 0.059 mT, which is comparable to the Earth's field. Such results make possible a number of new experiments in magnetic r esonance imaging (MRI). We present a two-dimensional image of a phantom fil led with mineral oil obtained in a field of 2 mT.