Functionalization of micro-Hall effect sensors for biomedical applications utilizing superparamagnetic beads

Fabrication of Hall sensors that are compatible with biological environments has been accomplished in an effort to provide an analytical tool for the detection, identification and quantification of deoxyribonuclaeic acid. Sensors are formed by InSb thin films grown on (100) GaAs wafers. Amorphous silicon nitride was deposited as waterproof sensor insulation, and topped by a gold overlayer serving as an interface for the immobilization of biomolecules. The key analytical processes utilize hybridization of complementary strands of oligonucleotides as a biorecognition mechanism, closing a chain sequence leading to attachment of magnetic beads, where the thiol-gold chemical reactivity produces bonding to the sensor surface.