Biomagnetic measurements with an integrated YBa₂Cu₃O₇ magnetometer in a hand‐held cryostat Available to Purchase

With low‐noise magnetometers made from high‐temperature superconductors, mobile applications of superconducting quantum interference device (SQUID) magnetometry become possible. Due to the high volume heat of evaporation of liquid nitrogen, a SQUID magnetometer can be operated in a small size cryostat for some hours. For the first time biomagnetic measurements are presented using an integrated YBa₂Cu₃O₇ magnetometer mounted in a hand‐held cryostat with a content of 100 cm³ of liquid nitrogen. These measurements and the noise properties are compared to those made in a conventional cryostat. The low‐noise magnetometer consists of a multiloop pick‐up coil coupled inductively to a dc SQUID based on ramp‐type Josephson junctions with PrBa₂Cu₃O₇ barriers.