Magnetic Dynabeads® detection by sensitive element based on giant magnetoimpedance

A GMI-biosensor prototype was designed and fabricated using an amorphous ribbon. As a first step, a GMI response was measured with a model liquid media: suspension containing magnetisable Dynabeads® M-450. These beads can be used as biomolecular labels when coated with a specific antibody. The GMI change caused by their presence was measured with a biosensor prototype designed with a measuring cell containing an amorphous CoFeMoSiB-ribbon element. GMI was measured at a range of current frequencies from 0.3 to 10 MHz and at intensities of either Irms=3 or 4.5 mA. Commercial Dynabeads® M-450 were supplied as a suspension in a phosphate buffered saline. A maximum difference of 25% in the GMI ratio measured with and without Dynabeads® was obtained at a frequency of 3.5 MHz and Irms=3 mA. Some potential applications for GMI-biosensor and further directions are proposed.