Contactless magnetic nanoparticle detection platform based on non-linear GMI effect

A detection platform based on non-linear Giant Magnetoimpedance Effect was analyzed for the design of a contactless and low-cost detector of magnetic nanoparticles. The sensor consists of two soft magnetic amorphous wires (Co66Fe2Si13B15Cr4, 1.5 cm in length) placed in parallel and connected electrically in series. Initially, a simple voltage divider was employed to characterize the variations of the first, V1fand second harmonic, V2f, voltages. Their response was analyzed under the effect of the remnant magnetic field generated by different amounts of Fe3O4 nanoparticles (mean diameter 140 nm) as a function of an external magnetic field, H. Due to the larger relative variations showed by V2f, the second harmonic was chosen for the final prototype development. An electronic interface was designed for both current excitation and V2f detection. The designed detection platform, characterized by high detection sensitivity, low-cost, portable, and reusable features, can be employed to efficiently detect magnetic nanoparticles.