An electrode for an electrocardiograph used for measuring potentials of a number of points of a body surface near the heart and producing an isopotential map thereof, has a plurality of spring-loaded rods movably mounted for reciprocal movement in the direction of the lengths thereof and urged toward...http://www.google.es/patents/US4550735?utm_source=gb-gplus-sharePatente US4550735 - Electrode for an electrocardiograph
