Measuring device for weak and slowly changing magnetic fields, in particular for biomagnetic fields

A magnetic field measuring device comprising a cantilevered, mechanically vibratable, rectangular substrate strip having a long axis and a short axis, at least one flat side of the substrate strip being coated with a magnetostrictive material system, further comprising drive means designed for temporally periodic exertion of a force component directed perpendicular to the flat sides of the substrate strip on at least part of a flat side of the substrate strip with a predetermined excitation frequency, and comprising a detection device for detecting an electrical signal generated by the vibration of the substrate strip, wherein

• the substrate strip is formed from a material with a modulus of elasticity greater than 5 GPa,
• the detection device has an induction coil which surrounds the substrate strip in a contactless manner and has a coil axis aligned along the substrate strip, and
• the predetermined excitation frequency is a function of the dimensions of the substrate strip such that the substrate strip oscillates in mechanical resonance and forms a U-mode, wherein a U-mode is a bending of the strip along the short axis in the shape of a symmetrical arc open upwards or downwards,
• wherein the substrate strip oscillates in mechanical resonance and forms a U-mode with at least one nodal line and the induction coil is formed from at least two coaxial, non-overlapping, series-connected partial coils, wherein each two adjacent partial coils have opposite winding directions and are arranged on different sides of the at least one node line.