Single Hole Based Magneto-Impedance Biosensor for Particle Detection

GMI (giant magneto-impedance) sensors have been used for biomedical applications that require maximum sensor detection sensitivity for accurate magnetic field detection. To create better biosensors, Fe₃O₄ nanoparticles are applied to holes drilled into a ribbon-based GMI biosensor which should increase the sensor detection sensitivity. A focused ion beam is used to drill various sized holes – 3, 4, 5, 7, and 10 μm diameters – into soft ferromagnetic Metglas® 2714A ribbons. The sensor sensitivity of these samples is measured as-cast, with holes, and with iron oxide nanoparticles at frequencies between 50 and 175 MHz. The addition of iron oxide nanoparticles has shown to increase the sensor sensitivity of the samples while the GMI ratio decreases. In conclusion, the sensor detection sensitivity of ribbon-based GMI biosensors improves when the iron oxide nanoparticles are applied and measured between 110 and 150 MHz, therefore, creating biosensors with greater detection sensitivity. The maximum sensitivity measured for the ribbon as-cast was 60 %/Oe, this increased to 105 %/Oe when the iron oxide nanoparticles were applied.