Four-channel YBa2Cu3O7−<i>y</i> dc SQUID magnetometer for biomagnetic measurements

Abstract

A four-channel YBa2Cu3O7−y thin film dc SQUID magnetometer was fabricated. Biomagnetic measurements were performed by using the four-channel system at 77 K in a magnetically shielded room. We have successfully measured four-channel magnetocardiac signals clearly in real-time mode. The best magnetic field resolution of the four SQUIDs was 370 fT/Hz1/2 at 10 Hz and 200 fT/Hz1/2 in the white noise region.