Biomedical comparison of magnetometers for non-ferromagnetic metallic foreign body detection

The location and surgical removal of foreign bodies in patients is still challenging, especially for firearm projectiles, which are small and non-ferromagnetic. Conventional location techniques use ionizing radiation, posing health risks while the procedures often last several hours and end unsuccessfully. The use of high sensitivity magnetometers provides a noninvasive and innocuous alternative for metallic foreign body location. The developed technique consists of a primary AC magnetic field generator (a solenoid) inducing eddy currents in non-ferromagnetic metallic foreign bodies, which results in an ultra-low secondary magnetic field that can be measured. This work compares the initially developed theoretical technique using Superconducting Quantum Interference Device (SQUID) magnetometers with the developed prototypes using lower cost alternatives, namely Giant Magnetoresistance (GMR) and Giant Magnetoimpedance (GMI). The comparison is based on biomedical device requirements for widespread clinical application. The proposed GMI location system is deemed the most qualified for clinical use.