HTS SQUID gradiometer using substrate resonators operating in an unshielded environment - a portable MCG system

We have demonstrated and verified the basic feasibility of performing magnetocardiographic (MCG) measurements without magnetic shielding when using a first-order electronic gradiometer with our novel dielectric substrate resonator rf SQUIDs. The setup at the operation site involved adjustment of the gradiometer's baseline length and adaptive balancing. Our experimental portable system was tested in three environments differing in the level of electromagnetic interference.