INTEGRATED YBA2CU3O7-X MAGNETOMETER FOR BIOMAGNETIC MEASUREMENTS

An integrated de superconducting quantum interference device (SQUID) m agnetometer has been fabricated using a YBa2Cu3O7-x-SrTiO3-YBa2Cu3O7-x multilayer process. The magnetometer consists of a 8.3 mmX8.6 mm pick up coil coupled inductively to a small washer-type SQUID with 9 Ohm bi crystal junctions via an integrated 10 1/2-turn input coil. Using simp le direct-coupled read-out electronics with additional positive feedba ck, a noise level of 9.7 fT/root Hz at 1 kHz and 53 fT/root Hz at 1 Hz was measured inside a magnetically shielded room. Due to the low nois e level biomagnetic heart and brain signals with high quality and the very weak signals of the peripheral nerve system were recorded. (C) 19 96 American Institute of Physics.