What is a Squid?
SQUID is an acronym for Superconducting Quantum Interference Device, a uniquely superconducting electronic device discovered in the mid-1960s that is an exceedingly sensitive detector of magnetic fields. Commercial SQUIDs that are sold today (by Conductus and others) can measure magnetic fields 100 billion times smaller than the earth’s magnetic field (which is itself quite tiny). With such sensors, signals as weak as the magnetic signature of electrical currents flowing in the human brain can be readily detected.
