Superconducting Helmet. SQUID used to measure brain magnetic fields

SQUID helmet application to measure magnetic fields of the brain. Shown is the exterior wall of the helmet’s thermos, which maintains the liquid helium at cryogenic temperatures. Even though the top of the patient’s skull is just centimeters from a pool o
Los Alamos physicists study MEG superconducting helmets which are composed of 155 SQUIDs, to provide "whole head" brain-current images. The MEG helmet offers improved capabilities that could help make magnetoencephalography, or MEG more common in hospitals.
SQUIDs, or Superconducting Quantum Interference Devices, invented in 1964 by Robert Jaklevic, John Lambe, Arnold Silver, and James Mercereau of Ford Scientific Laboratories, are used to measure extremely small magnetic fields, They are currently the most sensitive magnetometers known, with the noise level as low as 3 fT•Hz−½. While, for example, the Earth magnet field is only about 0.0001 Tesla, some electrical processes in animals produce very small magnetic fields, typically between 0.000001 Tesla and 0.000000001 Tesla. SQUIDs are especially well suited for studying magnetic fields this small.
Measuring the brain’s magnetic fields is even much more difficult because just above the skull the strength of the magnetic field is only about 0.3 picoTesla (0.0000000000003 Tesla). This is less than a hundred-millionth of Earth’s magnetic field. In fact, brain fields can be measured only with the most sensitive magnetic-field sensor, i.e. with the superconducting quantum interference device, or SQUID.

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