YBa2Cu3O7 thin film SQUID gradiometer for biomagnetic measurements
- 12 April 1993
- journal article
- Published by AIP Publishing in Applied Physics Letters
- Vol. 62 (15) , 1824-1826
- https://doi.org/10.1063/1.109561
Abstract
Low-noise rf SQUID washers fabricated from YBa2Cu3O7 epitaxial thin films have been used to construct a first-order electronic gradiometer operating at 77 K and suitable for biomagnetic measurements. Mechanical adjustment of the two-SQUID gradiometric setup made it possible to attenuate signals due to far magnetic field sources by three orders of magnitude. A magnetic field resolution of ≤280 fT/Hz1/2 above 2 Hz was attained through the use of large flux focusers. The fine structure of human heart magnetocardiograms was recorded in unshielded space. In a shielded room, magnetoencephalograms were obtained. The system was used to obtain new data on auditory evoked cortical response.Keywords
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