Broadband SQUID NMR with Room-Temperature Samples

Superconducting quantum interference devices (SQUIDs) are the most sensitive detectors of magnetic fields. We have used an untuned broadband SQUID detector to detect transverse nuclear magnetic-resonance signals from samples of mineral oil, salt water, and animal tissue at room temperature. Proton NMR signals have been detected from about 20 to 450 kHz. We have also detected fluorine, sodium, and possibly phosphorus NMR signals. SQUID NMR shows promise in NMR imaging, since the SQUID′s sensitivity and broad bandwidth make it ideal for low-field imaging. SQUID NMR may also be useful for low-field spectroscopy in biology, chemistry, and materials science.