An extremely sensitive, superconductor-based magnetic sensor can work at around 77 kelvin, a temperature achievable with liquid nitrogen rather than the expensive liquid helium required by typical existing devices, which operate at just above absolute zero.

Superconducting quantum-interference devices (SQUIDs) can sense individual quanta of magnetic flux by measuring voltage induced in a loop of superconducting material. Boris Chesca of Loughborough University, UK, and his team connected hundreds of loops in series to boost the signal. The authors say that their SQUID design is as sensitive as many devices already in use and is ready for production. The higher operating temperature makes it ideal for applications such as portable magnetic resonance imaging machines, they say.

Appl. Phys. Lett. 107, 162602 (2015)