A GMI biochip platform based on Co-based amorphous ribbon for the detection of magnetic Dynabeads
We describe a giant magnetoimpedance (GMI) biochip platform for the detection of streptavidin-coupled magnetic Dynabeads of different sizes. The GMI sensor based on micro-patterned Co-based amorphous ribbons (Metglas® 2714A) with a meander structure was fabricated by micro-electro-mechanical-systems (MEMS) technology. A gold film was then deposited on the GMI element to act as a support platform for immobilizing various concentrations of magnetic Dynabeads (1 μm and 2.8 μm). The results indicate that Dynabeads of 1 μm in diameter with a concentration as low as 5 μg mL−1 can be detected by using the ribbon-based GMI sensor, and that the detection limit for Dynabeads of 2.8 μm diameter was 1 μg mL−1. Besides, using the same number of magnetic Dynabeads with different sizes, the GMI responses were significantly enhanced after coating the 2.8 μm Dynabeads. The ribbon-based micro-integrated GMI biosensor is easy to fabricate and is expected to be used for the detection of very low concentrations of Dynabead-labeled biomarkers.