Giant Magnetoimpedance Effect for Magnetic Nanoparticle Detection and Biosensors: A Review

Giant Magnetoimpedance (GMI) refers to the pronounced variation in the complex electrical impedance of a soft magnetic conductor under an external magnetic field, governed by the magnetic field–dependent skin depth at high frequencies. The GMI effect has become a key principle for the development of ultra-sensitive magnetic field sensors, offering significant advantages such as roomtemperature operation, low power consumption, and high magnetic field resolution. This review provides a comprehensive overview of the fundamental mechanisms of the GMI effect in soft magnetic materials, including amorphous wires and ribbons, thin films, multilayers, and nanocrystalline systems. Beyond the fundamental aspects, recent advances in GMI-based technologies for biosensing and biomedical applications are critically discussed. Special attention is given to magnetic nanoparticleassisted detection strategies, where magnetic labels induce measurable changes in impedance, enabling highly sensitive detection of biomarkers, pathogens, and bioanalytes. The capability of GMI sensors for real-time monitoring of weak biomagnetic signals, such as those in magnetocardiography, is also highlighted, demonstrating their potential as compact and cost-effective alternatives to conventional systems. Furthermore, the integration of GMI sensors with microfluidic and lab-on-achip platforms is reviewed, emphasizing their role in rapid, portable, and multiplexed bioanalytical systems. Finally, current challenges and future perspectives are addressed.