SQUID

A SQUID (for superconducting quantum interference device) is a type of very sensitive magnetometer with very low noise characteristics. SQUIDs use superconductivity, requiring cryogenic temperatures. They can be miniaturized and incorporated in chips, which can feature arrays of SQUIDs, and means have been developed to extract data from individual SQUIDs within arrays. SQUIDs can amplify electronic signals, but I haven't found out about the mechanism.

In astronomy, SQUIDs are incorporated into transition edge sensor (TES) bolometer arrays: a means has been developed to pass the signal from the TES circuit to a SQUID (the TES is given a circuit element to produce a tiny magnetic field and the signal is transmitted through induction, essentially functioning a transformer), and SQUIDs are used to amplify and output the signal from the chip to other electronics. Both TES circuits and SQUIDs require a cryogenic environment.

SQUIDs are also used in other kinds of extremely sensitive instruments, including the sensors in some types of dark matter detectors.

SQUIDs also have potential as sensors in biology and medicine.