Conclusion
SQUIDs and their applications

SQUID magnetometers are indisputably the most sensitive magnetic field sensors. However, the commercial success of helium-operated devices is limited to a few niches (magnetoencephalographic mapping, susceptometry, NMR, metrology, etc.) due to their construction and maintenance costs.

SQUIDs in critical high-temperature superconductors, involving reduced cryogenics, are particularly interesting despite their lower sensitivity. High-temperature superconductor technology has evolved considerably in recent years, as have the electronics associated with SQUIDs. The sensitivity of magnetometers, mainly etched in YBaCuO films, has been improved by a factor of around 100; encapsulated devices integrating a HT SQUID_c, modulating inductors and a heating element, are now commercially available. However, further progress is needed in terms of reproducibility, handling and sensitivity in noisy...