Heart monitoring with high- d.c. SQUID gradiometers in an unshielded environment

We have developed one-channel high- d.c. SQUID heart monitoring system for non-invasive measurements in an unshielded environment. This system gives fast and reliable information about the heart condition of a patient, for example in an emergency case. Planar galvanically coupled thin film gradiometers and magnetometers with step-edge and bicrystal junctions have been prepared. These sensors were used to carry out magneto-cardiogram measurements in a magnetically shielded room with open doors as well as in an unshielded environment. The results of these measurements are presented and different filtering and averaging methods of the data discussed.