Mechanical resonator for sensitive magnetometry of bone

• Mammalian bone is diamagnetic. • Low frequency magnetic field is used in orthopaedic medicine. • Bone vibration in the magnetic field is measured. The information about magnetic properties of bone structures in their native state is typically lost during a destructive process of sample preparation for susceptometry by sample reduction to a powder. The low value of the magnetic susceptibility of bone’s mineral component, hydroxyapatite, requires careful calibration of the measuring equipment and process, and introduces the chances of a systematic error. Limited sampling volume of the commercial susceptometers adds to the uncertainty about the magnetic properties of bone structure in the bulk. Taken together, the experimental difficulties of acquiring bone susceptibility data contribute to the scarcity of reliable information about the magnetic properties of bone in literature. We have developed a method that requires minimally destructive sample preparation and in principle can work with the whole bone fragments of small laboratory animals (vertebrae and femurs of laboratory rats). The method is scalable and amenable to modifications of the applied, inhomogeneous magnetic field. This is a report on an exploratory study designed to evaluate the feasibility of the method. It is derived from the first principles in electromagnetics and tested experimentally against measurements using commercial susceptometry.