Cm. Pegrum et al., INTEGRATED NIOBIUM DC SQUID GRADIOMETERS FOR NONDESTRUCTIVE EVALUATION AND BIOMAGNETISM, Journal of low temperature physics, 106(3-4), 1997, pp. 493-502
We describe the design and fabrication of thin-film Nb gradiometers wi
th integrated DC SQUIDs for use in non-destructive evaluation (NDE) an
d biomagnetism. Issues of sensitivity, imbalance and field response ar
e considered. Results are presented from eddy-current NDE in an unshie
lded environment of aluminium plates with sub-surface flaws, and from
biomagnetic measurements of spinal and peripheral nerve evoked fields.